University of Virginia Library

1982
PARK ROADS AND PARKWAYS
LAR 525

LECTURE 1: PREFACE

The geometry of road design begins with an origin and a destination;
this we translate into a direction. It is then through
a series of judgments employing our skills in fitting the ribbon
to lay lightly on the Land that we design the roadway. The simplest
design, of course, is a straight line connecting the origin and the
destination without regard for the topography or for those features
outside of the corridor within which the road is to be constructed.
Instead, we landscape architects strive to describe a line of ever-changing
curvature in locating the road that will preserve the
natural and historic landscape, that will least intrude on animal
habitat, that will lay like a feather on the ground surface, that
opens views to scienic features on the skyline, and that insures
safety for motorists who will use the roadway.

We begin the design with a 314 pencil on study paper over a
topo map. The first line we draw will set the quality for what
follows! It is the reverence we have for the Land and the exaltation
that comes when a beautiful line flows through the pencil that
designs a road! If our hearts don't beat with trepidation at that
moment, we'd do well to put the pencil down. Walk away! The intrusion
onto the Landscape and the consequences of construction are too
devastating to begin poorly.

Once we are inspired by images of that graceful movement over
the Landscape, we are compelled to draw the ribbon. The side of
the pencil leaves broad strokes of graceful curves that fairly
skate along the contours in a joyful melody in the out-of-doors.
That's road design, That's Landscape Architecture!

GLOSSARY:

Park Road - A scenic travel way of everchanging curvature within a
park, designed to lay lightly on land, for the purpose of
visitors' enjoyment of the scenic, natural and cultural features
being preserved and interpreted within or beyond the park
boundaries.

Parkway - An elongated park containing a scenic road connecting two
separated parks, distinguished by the following features:

• - The roadway is of everchanging curvature with cuts and fills
  kept to a minimum and side slopes are shaped to resemble the
  adjacent natural topography.

• - The roadway lays lightly on the land to impart a sense of
  effortless flight through the countryside.

• - The scenery is enjoyable and unsightly views and noise are
  screened by vegetation or topography.

• - Grade separation structures insure limited access from
  adjacent roads.

• - Indigenous plant species are used to blend the right-of-way
  with the native landscape.

• - Safety is a primary design consideration to reduce accidents
  to an absolute minimum.

• - Medians of varying width may separate roadways having independent
  plans-and-profiles.

• - Vistas and views are directed toward features of interest
  beyond the right-of-way.

• - Billboards are eliminated.

• - Design speed increases gradually from the beginning to fit the
  topography and decreases toward the end of the roadway.

Tangent - A straight segment of road; the straight line between
P.I.s; the distance between the end of one curve and the beginning
of the next curve (between P.C. and P.C.).

Circular Curve - An arc of constant radius common to two tangents.

Spiral - A curve of gradually decreasing radius beginning at a point
on the tangent and ending at a circular curve (an exception is
P.S.S.).

Transition Curve - A change in direction composed of a spiral, a
circular curve, and another spiral; terms "transition: and
"spiral" are often synonomous.

"P" Line - The line composed of tangents connecting Points of Intersection;
sometimes a Preliminary Location.

Chord - A line connecting the ends of a circular curve, or a vertical
curve, or a tenth-part of a spiral.

Superelevation - The rate of rise of the outside edge of pavement
to compensate for centrifugal force of a moving vehicle.

Assumed Design Speed (from Barnett) - "The maximum approximately
uniform speed that probably will be adopted by the faster group
of drivers but not, necessarily, by the small percentage of
reckless ones." (NOTE! The principal factor affecting the
choice of a design speed is the character of the terrain.)

Compound Curve - A change in direction composed of two or more
differing radii; a feature to be avoided in alignment.

Broken Back - Two circular curves in the same direction connected
by a short tangent.

Vertical Curve - A parabolic curve connecting two vertical tangents;
usually a curve on a profile.

Degree of Curve - The angle subtended by 100 feet of arc.

Radius - The distance from an arc to a common perpendicular point;
the ground distance from a compass point to the curve.

Location - That place on the ground where a road is built.

Alignment - The projected line along which a road is designed or
is built.

Subgrade - The surface on which imported material is to be placed;
the interface between residual soil and the subbase of the road.

Grade - Gradient along the profile; to move soil or material; an
elevation; to manipulate contours on paper; to sculpture the
ground surface.

P.I. - Point of intersection of the main tangents.

P.C. - Point of curvature at the beginning of a circular curve.

P.T. - Point of tangency at the end of a circular curve.

Excavation - The volume of material removed below the original
ground surface.

Embankment - The volume of material deposited on the original ground
surface or above the subgrade.

Borrow - The volume of material imported to account for shrinkage
of excavation.

Profile - The graphic vertical alignment; the line delineating the
existing ground surface.

Plan - The proposed horizontal alignment.

Grade Separation - A bridge separating roadways.

Interchange - A system of roads and ramps connected to a grade
separation structure.

Intersection - An at-grade junction of two or more roads.

AASHO (now AASHTO) - American Association of State Highway (and
Transportation) Officials.

THOUGHTS ON THE HISTORY OF ROADS

The anthropologists tell us that the human species originated
in the savannahs of Africa, a landscape netted with animal trails
connecting watering places to grazing places to nesting places. As
the lower waterholes dried up each year, the herds moved to higher
ground—and the early people followed as nomads on the migration trails.

When the early people invented The Wheel—and when they domesticated
The Horse—I do not know. But when they placed their burdens
on an axle between two wheels to be drawn by a horse, the trails
became two parallel tracks across The Land. We do know that the
people of the Middle East built a system of roads over the trade
routes and that the Greeks extended their military power over much
of that known world. It was the system of chariot roads that bound
together the Empire under Rome from the British Isles to the Holy Land.

The Horse, remember, had occupied much of North America before
the Ice Age—and disappeared before the first humans crossed the
narrow bridge of ice from Asia. The American Indian waited for the
Spanish Horse for over thirty thousand years if our interpretation
is reasonable. The Spanish carved a net of roads from Central
America to Florida and California and north to the Rockies and Plains.
What early Indian became the first Horseman able at last to pursue
the buffalo? and to fashion a teepee and travois to mark the American
Landscape along the buffalo trail?

The French, in their quest for furs, pushed upstream from the
St. Lawrence to Great Lakes to the Upper Mississippi and Missouri
and then downstream to the Gulf. They were voyageurs rather than
builders of roads. An American historian compared the early Europeans:
"The Spanish came for gold; the French came for furs; the
English came to stay." And so it was left to the English to build
the Kings Highway and Post Roads and to settle the Tidewater of the
Eastern Seaboard. The science of canal building was borrowed from
Europe to extend commerce and settlement above The Fall Line to
cross the Piedmont and thereby secure the British settlement against
the French who extended their influence into the Ohio.

It was the system of land grants and patterns of settlement that
followed the great rivers that caused roads in the East to become

meandering rather than straight. And it was the rectangular system
of surveys that caused roads west of the Appalachians to follow
straight lines rather than meandering routes.

Westward Expansion into the Northwest Territory required roads
and canals to cross the mountains. The National Road was started
from Baltimore and the Erie and C & O Canals were started from
Albany and Washington to reach the newly acquired lands. And in an
accident of time, the steam locomotive arrived to challenge the
freight wagon and canal barge.

The Horse pulled the wagons across the Western Plains and The
Rockies before the railroads met at Golden Spike in Utah. A system
of roads had been built westward to supply the Army forts along the
Oregon and the Mormon and Sante Fe Trails. Railroads were extended
to parallel the early roads and in some places were built over the
towpaths of the early canals.

The Civil Engineer had made the canals and railroads his realm
while he computed the excavation for waterways and tunnels, the gradient
for lift locks, and the curvature for steel tracks. He developed
tables for faster calculations and for uniformity of standards for
construction. He refined transition curves and superelevation of
tracks to provide a smoother ride and reduce maintenance of rolling
stock hauling the coal from the Appalachians to the cities and
factories of the East in a change from water-driven machines to steam
power.

Meanwhile, The Horse did what he'd done for decades: he worked
the farm, trotted the family to town, and was the pride of the avenue
and racetrack. Several of the Eastern States, in an effort "to get
the farmer out of the mud", built a system of farm-to-market roads.
Until 1918, remember, most Americans lived on farms, dependent on
The Horse for their livelihood whether they sold or consumed the
product of their labors. The hard-surfaced roads enabled The Horse
to draw heavier loads than he could drag through the mud—and he
could pull a car over steel rails even easier.

The bicycle flourished on the new hard surfaced roads, especially
after Mr. Firestone and other inventors discovered a way to make a
rubber tire to soften the ride and reduce the noise on the streets.

Henry Ford didn't invent the motor car—but he did introduce
methods which led to mass production of the machine at a cost many
Americans could afford. The farm-to-market roads were overtaken by
the motor car; then a box was placed over the rear axle and the
American farmer acquired a Truck! I don't know when the Ford Tractor
appeared on the family farm—but it was the farm-to-market road, the
motor car, and the tractor that caused the decline of Americans' love
affair with The Horse. In 1916 the first Federal Aid for Highways
Act was passed by the Congress to provide a nationwide system of
roadways for motor cars. The Horse has served Americans from the
1500s—over four hundred years!

Frederick Law Olmsted had designed the carriage roads of our
Country's great city parks before America was off and running into
the Age of the Automobile. He had designed bridges to separate
carriage traffic, and roads of ever-changing curvature for pleasure
in a rural landscape before the Civil Engineers switched their attention
from railroads to roadways. The partnership of Gilmore Clark,
Landscape Architect, and Jay Downer, Civil Engineer, led to the
interdisciplinary design of the Bronx River Parkway in 1922 and
the system of parkways in Westchester County.

Tommy Vint authored the interbureau agreement in 1926 which
provided for the design of park roads within the National Park
System to be done by Landscape Architects of the National Park
Service working with Civil Engineers of the Bureau of Public Roads.
Out of that agreement came the Blue Ridge Parkway, and then Skyline
Drive and Colonial Parkway; Stan Abbott and Ed Abbuel, Landscape
Architects of the Park Service worked with Engineers of the Bureau
of Public Roads during those years of the early 1930s.

The high-speed Autobahns built as defense highways in Germany
during the 30s so impressed General Eisenhower that he urged Congress
to authorize the 46,000 mile Interstate System in 1956. Until the
1950s when Detroit reached record auto production, the railroads
had been the primary carriers of freight and passengers. Long distance
bus travel and rapid truck deliveries over Interstate Highways
caused the railroads to decline; the failure of the railroads to
restore pre-World WarII passenger service and the abundance of low-cost

gasoline encouraged Americans to travel longer distances by
private automobile.

The Interstate Highway System was indeed influenced by the
successful features of the Parkways designed by Landscape Architects
and Highway Engineers. The Palisades, Taconic and Merritt Parkways
were limited-access roadways. The Parkways built in the Washington
area (Suitland to Andrews AFB, Baltimore-Washington to Fort Meade,
and George Washington Memorial Parkway to CIA Langley) were designed
by NPS Landscape Architects working with Highway Engineers of The
Bureau under the 1926 agreement authored by Tommy Vint. The American
Society of Landscape Architects elected Jay Downer and Frederick
Cron, two top-notch Highway Engineers, to Honorary Membership in the
Society. (Joseph Barnett, I have read, was also an honorary member.)

The State Highway Officials organized to lay out a national code
of uniform traffic controls and safety practices which proved to be
effective during the construction of the Interstate System. Funds
amounting to 90% of construction costs were allocated to the States
to design and build those segments of the System within their jurisdictions.
The Bureau of Public Roads was reorganized to become the
Federal Highway Administration in the Department of Commerce to
administer the funds allocated to the States and to insure compliance
with the guidelines laid down by AASHO.

The displacement and relocation of neighborhoods and families,
the accelerated rates of run-off, and the increased hazards of
water and air pollution due to highway construction became public
concerns. The Highway Beautification Act of 1965, the National
Highway Safety Act of 1966, and the National Environmental Policy
Act of 1969 were expressions of public opposition to the effects
brought about by the Interstate System. Signboards and visual
encroachments were regulated, roadside hazards were reduced, the
National Highway Safety Council was established, and environmental
impact statements were required. The luxury automobile, mile-a-minute
travel time, and the monotony of constant high speeds over
extended distances had arrived.

In 1972 the whole scheme suddenly stopped by what we now call
"The Fuel Crisis." The earlier prophesies by the scientists were

fulfilled—"the fossil fuels" (oil) was being exhausted by automobiles!
The economic power of the world shifted to the oil producing
countries—and the results were restrictions in the gasoline
supply, reduction of travel speeds at 55 MPH, and the redesign of
the automobile to increase fuel economy.

THE FUTURE:

Is the high speed freeway obsolete? What effects will rapid
transit have on our urban centers? How will space technology change
our concepts of travel? What are the alternatives in terms of fuels?
Will the helicopter become a common family vehicle? What is the
potential of the air-cushion vehicle? What are the substitutes for
the automobile? Can we produce alcohol from wood or corn in quantities
to replace oil?

COMPARISON OF PRIORITIES:

In 1972, the Year of the Fuel Crisis, 56,600 Americans were
killed on the highways. Today the rate is about 46,000, a reduction
brought about by the 55 MPH enforced speed limit, and other safety
improvements. The combat deaths during the War in VietNam were
about 46,600; training accidents, sickness and other causes boosted
that total to 56,600—ironically the same as our 1972 highway
fatalities.

Can we Landscape Architects help in saving American lives?
I believe we can.

LECTURE 2: ASLA POLICY AND LEGISLATION

We will consider the major legislative landmarks which are
especially significant to us as designers and we will consider the
policy statements which provide direction to us as everyday members
of the ASLA. I urge you to read the entire "ASLA Policies" contained
in the ASLA Members' Handbook and require you to read the following
ASLA Orders:

• No. 422.1 On Billboards

• No. 425.2 On Collaboration with the Other Design Professionals

• No. 421.2 On Conservation of Fine Scenery

• No. 421.3 On Encroachment on Park Lands

• No. 422.2 On Highways

• No. 421.4 On National Forests

• No. 421.5 On Preservation of Historic Sites

• No. 422.3 On Scenic Roads and Parkways

You will find that ASLA's interest in the location, design,
construction, and maintenance of roads and highways is as old as
the profession—we have been in this business a long time. (See
Historic and Archeological Preservation, FHWA, 1979 for following:)

1.

• The Federal-Aid Highway Act of 1916 has been amended a number
  of times since enactment; the intent has always been for financial
  support (50% to 90%) to the States in extending a nationwide
  road system within broad controls of compliance. That system
  accounts for two-thirds of the miles we Americans drive each
  year (and seventy percent of the fatalities we bring down on
  ourselves.) The Secretary of Transportation is authorized to
  administer funds to the States to program, design, construct and
  maintain the Federal-Aid Highways under their jurisdiction according
  to those standards laid down by the AASHO and to enforce
  those amendments to the Act of 1916 and subsequent laws.

2.

• Antiquities Act of 1906 made it unlawful for any person to
  "appropriate, excavate, injure or destroy any historic or prehistoric
  ruin or monument, or any object of antiquity—" situated
  on Federal Land; authorized the President of the U.S. to proclaim
  historic landmarks, historic structures, or objects of historic
  or scientific interests to be national monuments; authorized the
  

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  Secretary of Interior to grant permits for examination, excavation
  or gathering of objects of antiquity.

3.

• National Park Service Act of 1916 - established Service "to
  conserve the scenery and the natural and historic objects and
  the wildlife therein and provide for the enjoyment of the same
  in such manner and by such means as will leave them unimpaired
  for future generations."

4.

• Historic Sites and Buildings Act of 1935 declared it to be
  national policy "to preserve for public use historic sites,
  buildings, and objects of national significance for the inspiration
  and benefit of the people of the United States——"

  -Collect and preserve drawings, plans, and photos (beginning of HABS)

  -Make surveys to determine historical or archeological value

  -Investigate and study sites, buildings, and objects

  -Acquire gifts or purchase property for preservation

  -Make cooperative agreements to preserve or operate historic
  property

  -Develop educational programs

  -Restore, reconstruct, or maintain sites and buildings

  -Erect tablets and markers

  -Operate and manage properties including authority to charge fees,
  lease concessions, etc.

  -Organize corporations to manage or restore donated properties

5.

• Highway Beautification of 1965 - (Ladybird Johnson's Bill) required
  the States to control advertising signs along Federal-Aid highways,
  to screen junkyards, to implement a program of "Landscaping and
  Scenic Enhancement", to hold public hearings within the States
  in order to base standards and criteria (for landscaping and
  scenic enhancement.) Authorized funds to 75% of cost to compensate
  owners of signs and junkyards; added $325,000,000 to '66-'67
  Federal-Aid program for implementation of the Act.

6.

• National Historic Preservation Act of 1966 - declared that the
  spirit and direction of the Nation are founded on its historic past.

  -That historical and cultural foundations of the Nation should be
  preserved as living parts of community life and development
  in order to give a sense of orientation to Americans

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  -That, in the face of ever-increasing extensions of urban
  centers, highways, and residential, commercial and industrial
  development, present preservation programs are
  inadequate to insure future generations an opportunity to
  appreciate and enjoy the rich heritage of our Nation

  -That the Federal Government accelerate its historic and
  preservation programs and activities to encourage agencies
  and individuals undertaking preservation by private means,
  and to assist the States, local governments, and the NTHP
  to expand their preservation programs.

  TITLE I; Section 101, authorized the Secretary of Interior to:

  • -Expand and maintain a national register of districts, sites,
    buildings, structures, historic objects, architecture,
    archeology and culture—and to grant funds for the States
    to conduct statewide surveys and plans, for preservation,
    acquisition and development of historic properties.

  • -Establish programs for matching grants-in-aid to States for
    preservation of properties, architecture, archeology, and
    culture.

  • -Establish programs for matching grants-in-aid to NTHP (chartered
    10/26/49) to carry out its responsibilities.

    (appropriated $2,000,000 in 1966 and $10,000,000 for each
    of three succeeding years)

  TITLE II; Section 201, established an Advisory Council on Historic
  Preservation composed of 17 members, ten to be appointed by the
  President.

  Section 202 describes duties of the Council: to advise the
  President and Congress on matters of Historic Preservation, to
  encourage cooperation with the NTHP and individuals, to recommend
  that studies be conducted by the States and the effects of tax
  policies on preservation, to advise and assist the States to
  draft legislation, to encourage training and education in the
  field of historic preservation; requires Council to submit annual
  report of activities.

  Section 203 authorizes the Council to secure information, suggestions,
  estimates and statistics from Federal agencies for purposes
  of historic preservation.

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  Section 204 states that the ten appointed members shall receive
  $100 per day plus their travel and subsistence expenses.

  Section 205 designates the Director of the National Park Service
  to be Executive Director of the Council, and to employ persons
  to carry out the provisions of the Act at the rate of $50 per day.

7.

• National Highway Safety Act of 1966 - established the National
  Highway Safety Council in the DOT, and required that "each State
  shall have a highway safety program approved by the Secretary,
  designed to reduce traffic accidents and deaths, injuries, and
  property damage resulting therefrom." The Act applies to safety
  programs rather than to design and construction or improvement
  work) and applies to all roads including those outside the
  Federal-Aid system; empowers the Secretary to reduce by 10% of
  Federal funds to States failing to implement a safety program,
  and to cut-off all safety funds for States failing to comply
  with the Act.

8.

• National Environmental Policy Act of 1969 declares that it is
  the policy of the United States to encourage productive and
  enjoyable harmony between man and his environment, to enrich
  the understanding of ecological systems and natural resources,
  and establishes a Council on Environmental Quality.

  Section 102 requires that policies, regulations, and laws of
  the Federal Government be interpreted and administered in accordance
  with NEPA; requires Federal agencies to use an interdisciplinary
  approach in planning and decision making; requires an
  EIS for all major Federal actions significantly affecting the
  environment.

  Section 103 requires agencies to review policies, regulations,
  and authorities and to recommend measures to bring these into
  conformity with NEPA.

  Section 104 requires Annual Environmental Quality Report to Congress.

  Section 105 establishes Council on Environmental Quality (CEQ)
  CEQ Guidelines:

  a.

  • Description of proposed action to permit a careful
    examination by other agencies

  b.

  • Probable impact on environment including wildlife and
    marine life.

  c.

  • Probable adverse effects and consequences.

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  d.

  • Alternatives to proposed actions.

  e.

  • Relationship of short term benefits to long term
    productivity.

  f.

  • Irreversible and irretrievable commitments of resources
    resulting from action.

  (Environmental Protection Agency authorized under Act)

9.

• Federal-Aid Highway Act of 1966 amended in 1968 declared that
  parkland, wildlife refuges, and historic sites were to be protected
  against encroachment by highway construction and that the
  Secretary of Transportation would not approve funds for highways
  affecting such lands unless there was no other feasible alternative
  and that all possible planning be done to minimize the
  effects of proposed highways.

  Twenty-three (approx.) other Acts govern the protection of
  migratory waterfowl and wetlands, archeological sites, wilderness
  areas, scenic rivers, air quality, and endangered species. The
  legislation described in detail (nine Acts above) are those
  most applicable to our interests and which we turn to in preserving
  Landscapes from highway encroachments. (Highways and
  Ecology: Impact Assessment and Mitigation, FHWA-RWE/OEP-78-2)

LECTURE 3: SAFETY

The National Highway Safety Act of 1966 laid down eighteen
standards authored by AASHO to improve highway safety through design.
Most deal with roadside design for which we landscape architects
have special responsibility.

The fact that about a third of the traffic deaths involve
collisions with some fixed objects within thirty feet of the pavement
prompted the Insurance Institute for Highway Safety to initiate
a study in 1973 through the law firm of Arnold and Porter of
Washington, D. C. The result of that study, The Law and Roadside
Hazards, by Fitzpatrick, Sohn, Silfen and Wood, is the basis for
much of the following discussion.

Eighteen recommendations of AASHTO contained in the Yellow Book:

1.

• Any feature found during plan review which is likely to cause
  accidents will be eliminated from the plan; safety characteristics
  will be deliberately designed into the plan.

2.

• Removal of roadside hazards will be paramount in safety programs
  of every state.

3.

• Field investigations will be made to evaluate existing and new
  designs of safety features for their effectiveness and cost.

4.

• Embankment and cut slopes 6:1 or flatter will be provided for
  improved vehicle recovery.

  

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5.

• Full width shoulders will be carried across all structures,
  flush with adjoining lane, and so marked to discourage through traffic.

  

6.

• Clear recovery areas will be provided at least 30 feet wide in
  rural areas and programs undertaken to eliminate trees, drainage
  structures, massive sign supports, utility poles; otherwise
  adequate guardrails will be provided.

  

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7.

• Gore areas (exits from a freeway) will be kept clear of fixed
  objects except that exit signs (permissible) will be mounted
  on breakaway posts.

  

8.

• Roadside will be reviewed continually to minimize signs and
  resist additions.

9.

• Necessary signs will be moved back from pavement at least
  30 feet.

10.

• Overhead signs will be used for increased visibility to all
  traffic for lane assignments.

  

11.

• Greater use will be made of existing overhead structures for
  mounting signboards.

  

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12.

• Breakaway lighting standards and sign supports are recommended;
  concrete bases will be flush with the ground surface.

  

13.

• Consistent policy for guardrail is needed nationwide; designers
  must regard guardrails as protection to the driver rather than
  protection to the roadway; guardrails approaching structures
  should be attached to the structure; approach ends will be flared
  and secured to the ground; mounting posts in medians will be
  6'3" apart; bolts will be fastened with washers to prevent their
  pulling through the rail.

  

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14.

• Median 60-80 feet wide is desirable; barriers will be considered
  for medians 30 feet wide or narrower.

  

15.

• Two-span bridges are recommended over divided highways to
  eliminate piers adjacent to outside shoulders.

  

16.

• Median barriers will be used between twin bridges crossing
  divided highways; median will be bridged on separations up
  to 20 or 30 feet.

  

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17.

• Truck climbing lanes will be provided on long grades; escape
  areas on long downgrades.

  

18.

• Lighting will be provided at critical locations and intersections;
  higher mounting heights will be used to reduce number
  of standards required, to place them farther from the roadway
  and to reduce glare.

  

The "Yellow Book" has become so widely accepted that it is
generally regarded as a standard by the States, by FHWA, and by
the courts. Surely this effort held a greater promise of achieving
nationwide uniformity than a Federally imposed standard because it
is authored by the State Highway Officials themselves and made a
part of FHWA's accepted standards.

* * * * * 

A quick review of the statistics will show the need for greater
commitment by all of us to the problems of highway safety:

National Safety Council - 1972 - reported that of 56,600
fatalities, 19,000 involved roadside hazards or overturning.

FHWA - 1968-1971 - reported that 51.8% of the fatalities on
Interstates were single car runoffs; most involved fixed objects.

Pennsylvania DOT - 1972 - reported that 682 of 2085 fatalities
were related to fixed objects.

The GAO, in reviewing FHWA's 1970 report, determined the following
cost-effectiveness data:

1.

• 4.78 lives could be saved and 86.96 injuries avoided for each
  $1 million spent on highway safety improvement work.

2.

• 0.77 life could be saved and 19.33 injuries avoided for each
  $1 million spent on regular construction on the Interstates.

3.

• 1.1 lives could be saved and 38.85 injuries avoided for each
  $1 million spent on safety improvement work on primary,
  secondary and urban roads.

GAO's conclusion: Highway safety improvement work is about five
times greater than regular construction work in lives saved, and
three times greater in injuries avoided.

These figures indicate that the need is to improve existing
roadways rather than to spend safety finds on new construction—
but the sad fact is, according to GAO, that during the seven years
following the 1966 Act, the States had spent only 2.1% of the Federal
apportionment on safety projects.

* * * * * 

In light of the statistics, let's look at the procedures under
which the States obtain Federal-Aid and the sequence of their projects
for new construction:

The State Highway Departments are required to submit a program
for FHWA approval to qualify for 50% (primary, secondary, urban
roads) or 90% (Interstate) financial aid. Following program approval,
the States proceed to:

1.

• conduct public hearings on proposed location and submit a
  report of the hearings including effects on air, noise, and
  water quality fo FHWA for approval. (location; draft of EIS)

2.

• prepare preliminary engineering programs and projects, (design)

3.

• conduct public hearings on preliminary design and submit a
  report to FHWA for approval. (EIS)

4.

• prepare right-of-way programs and projects. (acquisition)

5.

• prepare construction programs and projects and submit to
  FHWA for approval (PS & E)

6.

• construction according to plans and specs (inspected by FHWA)

7.

• final inspection (acceptance for compliance by FHWA)

8.

• maintenance (and public use)

Once PS & E approval has been granted, the Federal Government
has a contractural obligation for payment (50% to 90%). Upon completion
the State has sole responsibility for maintenance and can
initiate requests for safety improvement work in the future.

* * * * * 

In 1973 an amendment to the Federal-Aid Act of 1916 permitted
the Secretary of Transportation to issue a "Certification Acceptance"
to the States on the condition that the State would perform its
responsibilities in accordance with the laws and standards "at
least equivalent" to those in Title 23. Because progress was so
slow in the initiation of program requests by the States for safety
improvements, Congress appropriated separate money (from Federal-Aid
funds) for abatement of high-accident locations and removal of roadside
obstacles:

• 1974 - $50 million for high-accident-abatement on Federal-Aid Roads

• 1975-1976 - $75 million for high-accident-abatement on Federal-Aid Roads

• 1974 - $25 million for removal of roadside hazards on Federal-Aid Roads

• 1975-1976 - $75 million for removal of roadside hazards on Federal-Aid Roads

• 1974 - $50 million for both programs on all roads outside F-A System

• 1975-1976 -$100 million for both programs on all roads outside F-A System

The Secretary of Transportation, in an effort to implement the
1966 Act, issued eighteen standards for compliance, 3½ of which are
under the FHWA to enforce; the remainder are under the National
Highway Safety Bureau.

Standard 9 - requires each State to have a program for identifying
accident locations and for maintaining surveillance of those
locations.

I.

• The program shall have as a minimum:

  A.

  • A procedure for identification of accident locations:

    1.

    • to identify experience and losses

    2.

    • to produce an inventory of

      a.

      • high accident locations

      b.

      • locations where accidents are increasing sharply

      c.

      • design and operating features associated with high
        accident frequencies

    3.

    • to take appropriate measures for reducing accidents

    4.

    • to evaluate effectiveness of safety improvements

  B.

  • A systematically organized program

    1.

    • to maintain continuing surveillance for potentially
      high accident locations

    2.

    • to develop methods for their correction

II.

• The program shall be periodically evaluated by the State;
  an evaluation summary will be provided to the NHSB.

Standard 12 - requires that each State shall have a program of
highway design, construction, and maintenance to improve highway
safety.

I.

• The program shall have as a minimum:

  A.

  • Design standards relating to safety features for all new
    construction or reconstruction

  B.

  • Safe traffic environment for pedestrians and motorists in
    subdivisions and residential areas.

  C.

  • Roadway lighting provided on priority basis for:

    1.

    • urbanized areas

    2.

    • junctions of major highways in rural areas

    3.

    • locations of high night-to-day accidents

    4.

    • tunnels and long underpasses

  D.

  • Standards for pavement design and skid resistance

  E.

  • Program for resurfacing to improve skid resistance

  ---

  10

  
  
  

  F.

  • Control of traffic at construction sites and detours

  G.

  • Inventory of railroad crossings and program for elimination
    of hazards

  H.

  • Roadway maintenance is consistent with design standards

  I.

  • Hazards within ROW are identified and corrected

  J.

  • Design and construction features for accident pr vention
    and survivability for at least:

    1.

    • roadside clear of obstacles

    2.

    • 2. breakaway supports for control devices and lighting

    3.

    • protective devices wherever fixed objects can not be
      removed

    4.

    • bridge railings and parapets designed to retain vehicles
      and minimize danger to traffic below

    5.

    • guardrails to protect people from out-of-control vehicles
      at playgrounds, schools, commercial areas

  K.

  • post crash program which includes at least:

    1.

    • signs directing motorists to hospitals

    2.

    • personnel trained in summoning aid, protection at
      accident sites, removing debris

    3.

    • access and egress for emergency vehicles on freeways

II.

• The program shall be periodically evaluated by the State for
  effectiveness in reduction of accidents; an evaluation summary
  will be provided to NHSB.

Standards 13 and 14 - relate to traffic engineering and pedestrian
control; the other standards are administered by the NHSB:

 

1. Vehicle inspection 2. Vehicle registration 3. Motorcycle safety 4. Driver education 5. Driver licensing 6. Codes and laws 7. Traffic courts

8. Alcohol and safety 10. Traffic records 11. Medical emergency 15. Police services 16. Debris and clean-up 17. School buses 18. Investigation and reports

Subsequent instructional memoranda were issued by the Federal
Highway Administrator which specified that high speed design highways
would be those where design speed is 50 MPH or more with ADT of 750
or more. Those design standards contained in the "Yellow Book" are
accepted by the FHWA as supplements. (A separate list of AASHO
standards and specifications will be furnished to you during the
course for future reference.)

From time to time, FHWA issues additional standards which result
from observation of conditions or programs of research and testing:

culverts and bridges over streams, for instance, are to be designed
for 50-year frequency or the greatest flood of record with run-off
based on expected development on the watershed over the next 20 years;
inlets and pavement drainage are to be spaced so that nor more than
½ of a through traffic lane is flooded during a 10-year frequency
storm, except that a 50-year frequency is used at depressed sections.

Experiments have been conducted for the use of crash cushions
to absorb the impact of vehicles upon fixed objects. Three devices
are currently acceptable and testing of other devices is continuing.
Test criteria used by FHWA follows:

       

Vehicle weight range	2000-4500 pounds
Vehicle speed	60 MPH
Impact Angle	0°-25° measured from roadway
Average permissible deceleration	12 g's maximum, preventing impact with object

Minimum dimensions for a crash cushion are 6′x 8′ at 30 MPH,
6′x 17′ at 50 MPH, 6′x 28′ at 70 MPH, and 6′x 35′ at 80 MPH; the
preferred length and width of crash cushions are twice that size!

Summary:

Apart from the Laws regarding pendent jurisdiction, negligence,
sovereign immunity, liability, etc. which are too complex for me to
understand, are the responsibilities laid down by the ASLA and the
design standards laid down by FHWA as minimum measures of the designer's
performance. We must accept the duty to design in the expectation
that accidents will occur and that the recovery zone adjacent
to the highway must be safe for vehicles leaving the paved sections.

Designers have been brought to court (will be in the future) for
injuries suffered by motorists simply because our work effects the
public health and safety. The accident rate on our highways can be
improved by the judgment and competence of the designer. Our judgments
may be rejected for sound reasons, but we are obligated,
nonetheless, to present the safest design within the state of the
art and to raise our own level of competence constantly.

LECTURE 4 - CIRCULAR CURVES

See Seelye's pages 346-348 for Circular Curves and Functions of
1° Curve.

The Circular Curve is the basic geometry from which the spiral
developed. Even though we use a spline for road alignment of ever-changing
curvature, it is the circle from which we derive our geometry.

Circular curves have common properties regardless of scale; it
is through convention that we have come to use symbols to describe
their elements as we use abbreviations to describe the words of our
language: i.e., vs, na, AM, USA, etc.

Let us start from a circle made up of 360 arcs, each arc being
subtended by one degree, and each arc having a chord of 100 feet.
The circumference of our circle, therefore, is 360 arcs times 100
feet equals 26,000 feet. Recall the equation for circumference:

For convenience we say, "a one degree curve has a radius of
5730 feet." Equations, then, are:

R = 5730/D OR D = 5730/R

Examples: Find the radius of a 5.12° curve.

The circle described has a radius of 1120′; 100′ of arc is
subtended by an angle of 5.12°; the length of the curve is unknown.

The definition, then, for degree of curvature is the angle
subtended by one hundred feet of arc.

                           

Symbols for Circular Curves:	Equations:
R - Radius of curve	R = 5730 ÷ D
D - Degree of curve	D = 5730 ÷ R
L - Length of curve	L = 100 x ÷ D
C - Length of chord	C = 2R x sin ½
▵ - Central Angle	▵ = D x L ÷ 100
T - Tangent distance	T = R x tan½
E - External distance	E = T x tan¼
M - Middle ordinate	M = R x (1-cos½▵)
d - Deflection angle	d = ½ D; d = c x D ÷ 100
c - Short chord	c = 2R x sin d
P.I. - Point of intersection
P.C. - Point of curvature
P.T. - Point of tangency

We use a steel tape to lay out curves which produces a series of
100′ chords to locate the centerline. On long radius curves that
field practice is acceptable; on short radius curves (say 1000′) we
use chords of 50′ and station the centerline accordingly. Remember
that we are laying out an arc of 100′ and that the chord is a
shorter distance. Use the equation c = 2R x sin d (where d is ¼D)
for short radius curves.

The circle template you bought at Bailey's or Mint Printing will
help you to locate the compass points from which to refine your
broad pencil line. It will save time.

Recall our work at Pen Park when we laid out a circular curve
using the transit and a hundred-foot tape. In that case we used a
deflection angle equal to half of the degree of curve; we then pulled
a hundred-foot chord to intersect the line of sight. We could have
set points at fifty-foot intervals by using half of the deflection
angles; or twenty-five-foot intervals by using a quarter of the
deflection angle.

It is imperative that we understand deflection angles and that
we be assured that the person on the instrument knows the procedure
as well! (There is a scar in Big Bend a thousand feet long because
I failed to understand deflections and assumed that the person on
the transit did!)

You might study the procedure of string lining to lay out field
work; I use two tapes in the field to lay out arcs and tangents, as
well as the tables of natural sines to lay out angles.

LECTURE 5: SUPERELEVATION

Barnett sought to improve the alignment of roads by keeping
tangents to a minimum and inserting superelevation throughout the
transition curve. In that way the physics of the moving vehicle
would be distributed throughout the spiral from the tangent to full
curvature. He used the spiral developed by Searles for railroads
which was based on ten compound curves except that Barnett used
chords to simplify staking the spiral in the field. All of Barnett's
tables, therefore, incorporate superelevation and transition based
on the Ten Chord Spiral. Survey crews stake out centerline and
edge of pavement directly from the tables.

LECTURE 5 - THE PHYSICS OF MOTION

Discussion: (See Transition Curves for Highways, by Joseph Barnett)

The design of roadways requires an understanding of the forces
at work throughout the travel path of the vehicle. You will recall
from your high school course in Physics that Sir Isaac Newton (1642-1727)
described Three Laws of Motion: (see The New Columbia Encyclopedia)

1.

• A body at rest tends to remain at rest or a body in motion
  tends to remain in motion at a constant speed in a straight
  line unless acted upon by an outside force; i.e., if the
  net balanced force is zero, then the acceleration is zero.

2.

• The acceleration a of a mass m by an unbalanced force F
  is directly proportional to the force and inversely proportional
  to the mass; or a = F/m

3.

• For every action there is an equal and opposite reaction.

Examples:

Law 1.

• An automobile travelling at 40 MPH on a straight roadway
  will continue to move at a constant speed except for the
  resistance of wind, the friction on the tires, or the
  friction of the internal parts of the vehicle.

Law 2.

• An automobile entering a curve will accelerate toward the
  center of the curve.

Law 3.

• All of the forces of a vehicle, whether moving or at rest,
  are transferred to the road surface; the road is the
  reaction force.

Definitions: (see College Physics, by C.E. Bennett; handout re
Centrifugal Force and Friction)

Centrifugal Force - The force necessary to keep a body travelling
at a constant speed in a circular path.

Centrifugal Force - F = mv/R; the reaction to centripetal force.

Coefficient of Friction - The ratio of the tangential force of
friction divided by the perpendicular force pressing the two
together. F = nN, where n is the nature of surfaces when velocity
is constant, and N is the normal force pushing the surfaces
together.

Condition of Equalibrium - Exists when the vector sum of all forces
equals zero.

Weight - The force of gravity; the pull of the earth on a body
measured in pounds.

Velocity - The time-rate of change of position (speed refers to
magnitude of velocity).

Acceleration - The time-rate of change of velocity; a vector quantity.

Force - Measure of displacement of mass; exemplified by force of
gravity.

Momentum - The product of mass times velocity, a vector quantity.

Mass - Measure of inertia; the property of an object which resists
change in motion.

Vector - The combination of direction and magnitude.

Torque - The product of force times its lever arm (radius).

SUPERELEVATION:

Railroad engineers learned that rolling stock and track were
subjected to greater lateral stresses at the beginnings and ends
of curves in the rails (changes in direction). In order to prevent
overturning, they adopted the practice of raising the outside rail
and lowering the inside rail (superelevation). They learned, too,
that the ride could be made smoother and the stress on rolling
stock could be reduced if horizontal curves followed gradual
changes (transitions) rather than abrupt changes (circular curves).
The engineers formulated tables combining the physical principles
of superelevation and spirals.

With the introduction of the automobile, the engineers used the
tables they had developed for railroads to lay out auto roads. Many
inserted superelevation into the tangent but omitted the spiral in
the belief that automobiles could make transitions within the travel
lane. Accidents on the highways increased where the transition
curves were omitted. Joseph Barnett, an outstanding engineer in
Public Roads Administration, argued for transition curves with superelevation
in order to improve safety and to provide a smoother ride
along a graceful curve. (He had gained experience earlier in the

design of parkways in Westchester County with Clarke and Downer.)

Barnett studied the behavior of drivers as they were affected
by superelevation and friction. He learned that drivers did not
adjust their speed to the importance of the road, but to the physical
limitations of curvature, grade, sight distance, and smoothness of
surface. He found that longer transitions were necessary at higher
speeds to encourage drivers to stay in their occupied lane rather
than encroaching on the adjoining lane.

Barnett learned, too, that vehicles traveling around a curve at
low speed tended to slide down the superelevated incline when centrifugal
force was reduced. An analysis of 900 driving tests showed
that resistance to transverse sliding was developed around a curve
at friction coefficients of 0.16 for speeds of 30 to 60 MPH, or
0.14 for speeds of 70 MPH. and that the limiting factor for ice was
10%, or about 1¼ inches per foot.

From these findings, Barnett applied the coefficients of superelevation
and friction to the equation for Equilibrium: the centrifugal
force of a vehicle traveling around a curve of constant radius
at a constant velocity is equal to the superelevation S plus side
friction F, i.e. the vehicle is not skidding.

Let us examine the equation for centrifugal force which is
represented by Wv2/gR, where W is the weight of the vehicle, v is the
velocity in feet per second, g is the acceleration of gravity in
feet per second, and R is the radius of the curve in feet:

Eliminate W, change v in feet per second to V in miles per hour, and
substitute 32.16 for g.

Barnett proposed that the maximum superelevation practical for
all but the sharpest curves should be 39% according to the following:

This would result in all but the flattest curves being superelevated
to 10%; therefore, Barnett argued, superelevation should
account for 75% of the design speed. For example, curves on a highway
with an assumed design speed of 60 MPH would be superelevated
to compensate for the centrifugal force developed at 45 MPH. Barnett
developed his tables for superelevation accordingly.

DRIVER BEHAVIOR:

Imagine yourself approaching a circular curve (without transition)
at 40 MPH; you slow down to stay within your lane or, if the
road is clear ahead, you encroach on the adjoining lane to maintain
speed. In either case you have selected a transition course to
travel around the curve. If you encroached on the adjoining lane,
you created a traffic hazard to yourself and to others.

Suppose, too, that the curve was superelevated and you drove
comfortably around the curve without skidding and increased your
speed where the road straightened out again. Had the curve not been
superelevated, you would have slowed down around the curve to avoid
skidding. You experienced the conditions Barnett intended to improve
to make roads safer.

In order to persuade engineers to design for transitions with
superelevation, he developed tables to simplify calculations and

reduce engineering costs. The tables were published in Barnett's
book, Transition Curves for Highways.

Because Barnett's tables resulted in minus superelevation for
curves flatter than 22° at 25 MPH, and 4.5° at 55 MPH, AASHO chose
to use the equation found in Seelye's:

You will find that Virginia Highways uses standard normal crown
and 0.0 superelevation for curves flatter than 22° at 25 MPH, and
flatter than 4° at 55 MPH.

LECTURE 6 - TRANSITION CURVES

Joseph Barnett is one of my great heroes who, with Frederick W.
Cron, argued for roads of graceful curvature and the preservation
of natural features within the road corridor. They were advocates
for road spirals.

We think of Transition Curves as having three components:.

1.

• The spiral from tangent to circular curve.

2.

• The circular curve

3.

• The spiral from circular curve to tangent

If we examine the shell of the Nautilus, we find in it the
epitome of the spiral. That quality of everchanging curvature eliminates
abrupt changes in alignment and in the rhythm of movement
over the landscape.

Joseph Barnett labored over a convenient method to persuade
designers to use Transition Curves rather than Circular Curves.
The time he devoted to the mathematical tables published in his
book Transition Curves for Highways must have been endless! A man
blessed with patience and dedication to improving the beauty and
safety of highways. (Recall the discussion of physics of a moving
automobile in the lecture on Superelevation.)

The availability of the computer makes Barnett's task easier
today. The tedious calculations are things of the past so long as
we are in an office; engineering costs are reduced and the results
are more quickly available.

THE CONCENTRIC CIRCLE TEMPLATE:

The template with concentric circles which you bought from
Bailey's or Mint Printing is one I developed out of a need to convert
a 314 pencil line to geometrics. It saves time and has been reproduced
many times in the Park Service. Within the Division of
Landscape Architecture we have a set of Highway Curves for drafting
arcs of greater radius than we can draw with the compass. We'll
practice with those during the weeks ahead. My greatest concern is
that you master the geometrics so that you can draw road centerlines
with a straight-edge, a compass, and a spiral curve template. Again,
it's what you need to know.

HOWLAND'S FOURTEEN STEPS:

My purpose in spending so many hours in developing a method
for you to use in calculating Transition Curves with a pocket calculator
is that you will be more effective in the field. If you
will remember what we did together in Surveying and in Park Roads,
you will be able to lay-out roads and hold your own.

Within the capabilities of Barnett's Tables, and Howland's
Fourteen Steps, you can indeed refine the Transition Curve where
the spiral of one curve will join the adjacent spiral at the same
point:

Furthermore, you can eliminate the circular curve altogether:

Combining the two features, the Transition Curve produced would
have neither tangents nor circular curves. The curves would be
transitional throughout.

THE ENGINEER-LANDSCAPE ARCHITECT TEAM:

Dick Montgomery, Chief Engineer and Ol' Ben, Chief Landscape
Architect, agreed that our procedure should require the Landscape
Architects to draw the preliminary road centerline. Drawings were
to show tangents connecting the P.I.s, the compass points for each
curve, the tangent points perpendicular to the compass points, and
the radius of the curve shown concentric to the centerline. The
purposes of our agreement were to communicate to the Design Engineer
the controls implied in the location of the centerline, and to overcome
the time-loss in Landscape Architects doing tedious calculations
that Engineers could do faster. Once the drawing was approved by
the Chiefs, the teams worked through the construction drawings and
put the specs together. It worked. The team approach was and IS
the secret to success enjoyed by the NPS.

THE SPLINE LINE:

You will be manipulating transitions during the design of your
road at Birdwood or your project next Fall. While you are refining
"Your Road", ask what might be the next refinement in striving for
the perfect line of grace and movement. What mathematical derivation

might lead to the absence of tangents altogether? And what
might we call that line?

Let me share an experience with you:

Soon after I was called into the office from the Tree Gang in
1951, I was amazed to see a "spline and set of spline weights."
As students, we had not seen those tools much less used them during
our time in school. I was fascinated by the skill with which Mr.
VanGelder and Mr. Hanson adjusted the direction and subtle refinements
of road centerlines. This was the magic of everchanging curvature
that Prof. Albrect had described to us. To my disappointment, I
neither acquired the skill that Mr. VanGelder and Mr. Hanson had
nor was my curiosity satisfied in the potential of the "spline
line." Very soon I found myself drawing road alignment for the
Bureau Engineers in terms of tangents and circular curves onto
which they imposed their mysteries to convert my crude line to
geometrics. The fascination for the "spline line" continued through
the years and to this day I want to master that highest of park
road geometrics, "The Line Without Tangents."

I don't know the procedure for calculating the "spline line";
although Nick Annese shows me that Clarke and Rapuano uses the
method as standard procedure. Perhaps Ol' Ben could learn from
those designers who use it.

In this day of computers the calculations could be done quickly.
Programming the computer is quite another matter...and I lack the
skill to do that. To those of you who are interested and possess
the skills in programming, I would encourage you to explore the
geometrics of the "spline line". Surely the spline line geometrics
will lead to a refinement of the methods I have presented to you
in this course.

LECTURE 7 - VERTICAL CURVES

Discussion:

Horizontal and vertical alignment are directly related and are
therefore designed as a ribbon having three dimensions. Horizontal
curves are contained within a single vertical curve to insure uniformity
of centrifugal force and friction. Vertical curves are also
a function of sight distance, gradient and headlight distance. Hans
Lorenz, an engineer experienced in design of German autobahns,
suggests a rule that the vertex of the horizontal curve should coincide
with the vertex of the vertical curve to avoid a rollercoaster
effect within a horizontal curve. F. W. Cron, an engineer of the
Bureau, points out that "most of the awkwardness of the highway
arises from failure to visualize the road in three dimensons during
the planning stage." Mr. Cron spent much of his career working
with us in the National Park Service.

Short vertical curves are to be avoided in any case even though
the vertex of the vertical coincides with the vertex of the horizontal
curve. Vertical curves often make up 50% of the profile and may be
greater on gentle topography. In the design of park roads, we strive
to make the appearance of the road forward as aesthetically pleasing
as geometry will permit. This criteria is made more difficult by
the requirement that cuts and fills be kept to an absolute minimum.

Virginia Highway's tables for minimum sight distance on vertical
curves show curves as short as 50 feet and as long as 2000 feet.
New York State requires a minimum sight distance of 1000 feet on
its Thruway. (Tunnard, page 193) My own opinion is that vertical
curves should not be shorter than 250 feet which is about the minimum
radius of a horizontal curve at 30 MPH (232 feet). The alternative
to shorter vertical curves is an elevated structure on sag curves;
summit curves are less difficult, usually, because landforms tend
to be rounded on convex slopes and sharper in valleys. Park roads
are by nature of low speed, and therefore sight distances are much
shorter than on high speed roadways. It is, after all, a principle
of controlling the speed at which drivers will travel the roadway
that park roads are built.

LECTURE 8 - DRAINAGE

An Engineer in the Park Service used to say, "... remember three
things about roads: the first is drainage, the second is drainage,
and the third is drainage!"

Road construction requires that runoff be intercepted in roadside
ditches before the water that falls onto the watershed reaches the
road prism. It is imperative that drainage be provided to prevent
ice forming in the roadbed and prevent soft spots from developing
under the road surface.

Keep in mind that ditches placed in most soils will erode at
gradients steeper than two percent; therefore, a series of drop
inlets is necessary along the ditchline at intervals not greater than
300 feet. Ditches on steep grades are sometimes paved with asphalt
or concrete to prevent scouring; rock lining is used to reduce velocity
of flow. Woven fabric is sometimes used in swales to encourage
the growth of turf.

One of the chief reasons for erosion of ditches and subsequent
sloughing of the slopes is the practice of shaping the ditch with
the blade of a patrol grader. The blacksmith at Yellowstone fashioned
a shoe made from steel plate which is attached to the blade
end; the form of the shoe produces a rounded ditch which is aesthetically
superior and more stable than the V-ditch.

We will review the Rational Formula which you learned in your
Grading course, and then Manning's Formula for the design of ditches.

Should the ditchline be a swale? a V-shaped channel? a rock
lined gutter? a rounded turf swale? Although the formulas dictate
the volumes of water to be accounted for, it is the immediate
setting that determines the kind of ditch you will build.

Subsurface drainage systems can be quite complex in areas where
the groundwater is close to the surface, or where adjacent soils
are subject to saturation and freezing and thawing in the Springtime.
The following details are taken from the Virginia Highway's book,
Road Design and Standards:

Drainage Structures are critical visual elements deserving
special design consideration where the structures are obvious to
the visitor. Standard details are minimums: we notice the ends
of culverts, the faces of drop inlets, the ends of bridge scuppers.
Design decisions are needed wherever drainage structures are conspicuous:
is design needed? is design not needed?

DIVERSION DITCHES:

Diversion ditches are frequently built above the cut face of
the slope to intercept surface water. The gradient of the diversion
ditch, being steeper than the roadside ditch requires a velocity
check before it joins the roadside ditchline or culvert. See the
case at Michie Tavern where paved ditches are joined at the toe of
slope; the need for a velocity check structure is obvious.

In situations where the centerline of the road is level, it is
necessary to draw a profile of the ditchline to insure flow of
water. Constitution Avenue in the District of Columbia is level;
the gutters are undulating with highpoints placed between drop
inlets. In developed areas water is collected in gutters rather
than ditchlines; therefore, the drop inlets and underground pipe
systems are designed as closed systems. Recall the exercise you
did in Grading for a closed system.

CULVERTS:

Early culverts called "pole drains" were probably nothing more
than poles laid in stream beds; these were simply voids under the
fill. Timber and masonry structures were developed to an art in
the construction of canals before Portland cement became a common
material. One of the culverts on the C and O Canal has a rifled
liner designed to increase velocity thereby reducing the area of
the opening to accommodate the volume of water reaching the culvert.
In some parts of the storm water system in the District of Columbia
we find pipes fabricated from wood staves bound by metal hoops.
Brick was extensively used for storm sewers and drop inlets. It
was not until the development of corrugated metal pipe that culverts
could be made cheaply; from the various shapes and sizes
available we can select the pipe which satisfies the flow requirements.

Concrete pipe has several advantages: the friction
coefficient is lower, the crushing strength is greater, and its
service life is longer than metal pipe. Terra cotta pipe is still
used where acid is prevalent in waste water. Cast iron is used
where heavy loads must be accommodated.

Culvert size is a function of volume, roughness and slope. Our
primary interest is in the soil surfaces at the ends of the pipe
where appearance is especially troublesome. Conspicuous culvert
openings may require masonry or concrete headwalls; outfalls may
require special velocity checks or provisions to spread the water
over a paved apron.

BOX CULVERTS:

Box culverts built of timber or concrete are designed to carry
loads on a slab placed over parallel walls; water is spread over
a broader surface than with round pipe. Box culverts over 20 feet
wide are classified as bridges and are therefore regarded as major
structures. These are often provided to connect cattle pastures
and to provide routes for wildlife to move from one habitat to
another. Bridges usually cause a lesser impact on the land than the
fills associated with box culverts. Multi-box and multi-arch culverts
are used to reduce the depth of fills necessary to accommodate
larger single pipe sizes.

CAUSEWAYS:

Causeways are bridges in effect; the roadway is supported either
on a long earth fill over a series of culverts or on a timber or
concrete slab resting on piling. Earthen causeways are inappropriate
in tidal areas and marshes where the ebb of water is critical
to the quality of aquatic habitat. Causeways make up most of the
Chesapeake Bay Bridge-Tunnel and are used to carry roadways across
Lake Pontchartrain and to connect the Florida Keys. The structures
provide a beneficial reef effect for fish populations; adversely,
they impose a narrowing of navigation channels. I do prefer pilings
to earthen causeways.

SELECTION OF STRUCTURES:

The consequences resulting from construction will determine
the choice of drainage structures:

1.

• The impact of the changes on wildlife habitat on the lower
  watershed.

2.

• The constriction and consequent impounding of runoff above
  the structure.

3.

• The visual encroachment of the structure itself.

4.

• The views outward from the roadway.

Vegetation along elevated structures will be different obviously
from vegetation grown on fill slopes; the former will favor wet
site species; the latter will favor dry site species. Our attitude
is on the side of preservation of natural vegetation provided that
sight distance not be obscured by vegetation.

LECTURE 9 - ROUTE SURVEYS AND ALTERNATIVE LOCATIONS

Discussion:

Proposals for road construction start with a recognized need
for the extension of a road system for the purpose of economy of
transportation, social need, maintenance access, or scenic experience.
Feasibility studies are conducted by highway agencies based
on origin and destination counts to determine anticipated traffic
volumes. In the case of park roads, the feasibility of a road proposal
begins with the Master Plan.

Procedure:

The landscape architect starts the project with the study of
the route on USGS sheets and stereo pairs of aerial photographs.
In some cases, topo maps at larger scale are available. The U. S.
Forest Service and Soil Conservation Service use maps and aerial
photos at a scale of l″ = 660′ or 80 chains to a mile. Several
routes may be studied on paper using a 314 pencil to determine the
economy of construction in terms of excavation. In park road design
where preservation takes precedent over economy, a corridor is
selected to conserve natural and historical features within the
immediate area and on the viewshed as well.

Reconnaissance Survey:

Team members (engineer, geologist, biologist, resource manager,
landscape architect) walk the route using a compass or Brunton and
pacing distances. Flags are tied to tree limbs or on laths to mark
the line. The multidisciplinary team on the reconnaissance survey
argues over every detail along the route until agreement is reached.
The road then belongs to the Team! Once the flagged line is accepted,
the route is drawn on a topo base map.

Preliminary Survey:

Survey crews are then sent to map the flagged line from the
beginning to each flag measuring (chaining) horizontal distances
and recording deflection angles at each change in direction. It is
imperative that the survey be closed or tied-down to known survey
points at the ends of the line! The survey is drawn on paper and

given to the landscape architect for refinement—-curves and tangents
are drawn between P.I.s, the centerline is stationed, and the deflection
angles are plotted to establish deltas for each curve. The
landscape architect and engineer examine the line to confirm those
details of location made by the team in the field. Once the alignment
is approved and before more design time is invested in the
project, the proposal is presented at a public hearing with a rough
draft of an Environmental Impact Statement. In the case of state
or county roads, a right-of-way drawing is made showing the properties
affected by the alignment.

Location Survey:

The preliminary alignment is then drawn by the engineer and
staked in the field. Hundred-foot stations and the P.C.s, P.I.s
and P.T.s along the centerline are staked. Elevations are then
taken on all centerline stakes (hubs) and cross-sections are taken
by stadia. The engineer then refines the horizontal and vertical
alignment and produces the final plan-and-profile drawing. Earthwork
calculations and mass diagrams are made during design to insure
economy. Geometrics, grading plans, cross-sections, subsurface
drainage plans, pavement drawings, and profiles for ditches, are
prepared. In the case of grade separation structures, the structural
engineer and landscape architect work together to prepare detailed
drawings of the exterior features of the bridges and major structures.
After construction drawings are prepared a second public hearing is
held to review the final Environmental Impact Statement and the
final design.

Construction Surveys:

Centerline stakes, slope stakes, grade stakes, and off-set
stakes are then surveyed in to lay out construction. The first
operation by the contractor is clearing and grubbing the site which
often knocks out survey stakes and causes constant replacement by
a survey crew!

Supervision:

Project engineers are assigned to supervise construction and to
administer contracts on those projects designated Major Roads by

the National Park Service and the Federal Highway Administration
under the Interbureau Agreement of 1926. Minor Roads are those
designed by engineers and landscape architects in the National
Park Service working "in house" without help from Federal Highway.
In both cases, the landscape architect works hand in glove with the
engineer to merge their talents in the design and construction of
park roads.

Study of Alternatives:

The process of public review requires that alternative locations
be considered before the final location is approved. Once the
corridor is selected to preserve the natural and historic features
from the impact of construction, alternate routes may be considered
on the basis of economy.

A quick technique to study excavation cost is to draw a profile
of the groundline and then to superimpose a centerline profile.
Then draw quick cross-sections at representative locations to
determine the average conditions. Rough calculations can be made
to compare the earthwork required in each of the alternatives.

The Taking Line:

The R.O.W. line requires difficult judgments when private properties
are affected by the land necessary for acquisition. Land
acquisition teams are employed to establish reasonable offers to
land owners; fair market values are the rule. I encourage you to
argue for the owners in cases where their lands are separated by
the proposed R.O.W., or where their homes will be dangerously close
to the proposed roadway. You've seen homes situated at the toes
of slopes where the owners would have faired better if their entire
land had been acquired and they had been relocated. You've seen
farms divided by elevated roadways and pastures connected by long
culverts to let cattle move under road fills. We must do better!

GRADE SEPARATIONS AND INTERCHANGES

from Chapter X, A Policy on Geometric Design of Highways and Streets,
NCHRP, December 1979

"The greatest efficiency, safety, and capacity are attained when
intersecting through-traffic laws are separated in grades." "The
type of grade separation and interchange along with their design,
is influenced by many factors, the principle factor being design designation....traffic volume, character of composition of traffic,
design speed, and type of control of access."

Other controls: signing, economics, terrain, right-of-way.
Basic type of interchanges can vary extensively in shape and scope.

• Fig. X-1A-Trumpet or jug-handle ramp configuration

• Fig. X-1B-Three-level, directional, three-leg interchange

• Fig. X-1C-Not suitable for freeways but practical for highway-parkway
  connections where trucks are prohibited and
  design speed is low

• Fig. X-1D-Typical diamond which has variations with frontage
  road and collector-distributor ramps

• Fig. X-1E-Partial cloverleaf which favors heavier traffic volumes

• Fig. X-1F-Full cloverleaf generates weaving movements that must
  occur on collector-distributor roads

• Fig. X-1G-Fully directional interchange-example is four-stack
  interchange in Los Angeles

Open-road capacities can flow without interruption when intersecting
roads are separated by a structure. The high initial cost
of grade separations must be justified on the two considerations of
(1) elimination of traffic bottlenecks, and (2) correction of existing
hazards. Six items (or warrants) will justify an interchange:

1.

• Design Designation: whether or not the access will be fully
  controlled between terminals

2.

• Elimination of bottlenecks or spot congestion: inability to
  provide essential capacity of one or both roads

3.

• Elimination of hazard: locations of high accident frequency

4.

• Site Topography: physical properties of site make at-grade
  intersection impossible

5.

• Road-User Benefit: costs due to delays, fuel, time and
  accidents require improvement; relation of road-user benefit
  

  ---

  2

  
  
  
  to cost of improvement; annual benefit divided by annual
  cost of improvement; annual cost is sum of interest plus
  annual amortization.

6.

• Traffic Volume: volumes exceed capacity of at-grade intersection;
  elimination of conflicts greatly improves movement
  of traffic.

Additional Warrants:

1.

• Local streets cannot be terminated outside of right-of-way

2.

• Access to areas not served by frontage roads or other access

3.

• Railroad grade separations

4.

• Unusual concentrations of pedestrians such as parks on both
  sides of roadway

5.

• Bikeways or pedestrian crossings

6.

• Access to mass transit within major arterial

7.

• Free-flow aspects of certain ramps and completing geometry
  of interchange

ADAPTABILITY OF INTERSECTIONS

Three general types:

1.

• At-grade intersections - traffic on minor road may be delayed;
  up to 50% may be required to stop

2.

• Grade separations without ramps - through traffic is not
  delayed or interrupted

3.

• Interchanges - suited for heavy traffic volumes

SAFETY

Interchanges reduce conflicts of turning traffic and through
traffic, substituting instead the less hazardous merging and diverging
movements. All-right turn movements are safer than crossing and
stopping movements.

STAGE DEVELOPMENT

Allows partial completion to serve current conditions with option
to expand interchange to meet future traffic volumes.

ECONOMIC FACTORS

Initial cost is greater on interchanges; maintenance is also
greater; vehicular operating costs are generally lower at interchanges.

STRUCTURES

MAJOR STRUCTURES:

 

Bridges: -over streams, broad water -grade separations -elevated roadways -pedestrian crossings -bike crossings -railroads

Tunnels: -mountain ridges -ship channels -urban centers -airports

MINOR STRUCTURES:

 

Drainage: -culverts -diversions -impoundments

Other: -cribbing -retaining walls -cattle crossings

MISCELLANEOUS STRUCTURES:

       

Dams	Weigh stations	Emergency access
Breakwaters	Overhead signs	Lighting systems
Truck escape ramps	Cattle guards	Guardrails
Entrance gates	Maintenance access

DESIGN FACTORS:

a.

• Resistance to temperature changes, earthquake, bouyancy, earth
  pressure, erosion from chemicals or stream sediments, ice load

b.

• Live loads - weight and dynamics of vehicles including impact

  Dead loads - weight of structure itself

  Wind loads - may include flooding, ice, currents

c.

• Standard specifications for vertical and horizontal clearances

d.

• Special uses: heavy vehicles, railroads, saddle stock, construction
  equipment

BRIDGE TYPES:

         

Deck slab	spans up to 60 ft.	Note: Timber may be used for spans up to 20 feet.
Girder	spans up to 150 ft.
Truss	spans up to 300 ft.
Arch	spans up to 300+ ft.
Suspension	spans up to 1000+ ft.

LECTURE 11- SLOPES

Consider the elements which make up the cross-section of a roadway:
the cut-slope extends from the feather edge above the excavation
downward to the ditchline; the fill-slope extends from the
shoulder edge downward to the feather edge of the embankment; other
elements are ditches, shoulders, and pavement. Slopes take up most
of the road prism; they are the transitions from the ditches and
shoulders to the limits of grading. The appearance of the roadside
and the views to distant features beyond the roadway are largely
the result of the landscape architect's skills in drawing the grading
plan.

Construction manuals show standard sections with slopes of 1:1
or 2:1 as though the slopes are mathematic conveniences for estimating
earthwork. In my observations there are no standard slope ratios to
fit all soil conditions along the roadway. Look for the steepest
natural slope in the adjacent area; that slope ratio is stable for
similar soils in that segment of the roadway. If we use a slope
steeper than the angle of repose, we will be cleaning ditches from
now on!

Observe the cut-slopes in the Piedmont of Virginia; 2:1 slopes
are unstable because of the high clay content. Slopes of 3:1 or
flatter are more stable.

It is essential that we show on the drawings the material to be
encountered in the excavation; therefore, study the soil maps and the
boring charts before you begin a grading plan. And go to the field
to find indicators of changes in soils! Rock outcrops, rock strata
in streambeds, sediments deposited at grade-breaks won't show on
topo drawings.

Bidders will increase their bid prices for unclassified excavation
to play it safe. Estimators will allow for rock excavation
because it requires blasting. Therefore, your bid prices will be
more realistic if you show the slope ratio for given soil types
according to the conditions you expect to encounter. Field inspection
will show the stable slope of shale or decomposed granite
more accurately than the standard slope ratio shown in the construction
manual.

Howland's Theory:

I have a theory to share with you. It is that a slope resembling
a natural curve is more stable than an artificial curve. If we
determine the angle of repose for a particular soil, a Catenary
Curve taken from the midpoint of the slope downward through the
ditchline to the shoulder will be stable. If the same curve is
reversed and extended upward to the feather edge of the cut-slope,
the face of the slope will then be in equilibrium. That convex/
concave slope is what we see in the landscape. If we accept the
definition that the angle of repose is that gradient at which a
particular soil will stand when fully saturated, the slope will
then be in equilibrium. I intend to test the theory to prove its
logic and will tell you the results later.

Therefore, slopes are transitions in elevation. A drop of
rainwater falling at the crest of a convex slope will increase in
velocity as steepness increases. If the lower slope is made concave,
the acceleration will be reduced until the drop of rainwater arrives
at the ditchline.

The Seedbed:

Road slopes are a giant seedbed beyond the pavement on which
seeds will germinate under conditions of sunlight, moisture and
sufficient nutrients to support growth.

Moisture which reaches the root systems of plants is in part a
function of steepness. The steeper the slope and the smoother the
texture of the soil surface, the faster will be the rate of runoff.
Runoff will penetrate the soil surface over a longer time period
on flatter slopes because the rate of acceleration is lower. We
know that snowpack will be retained longer on north and east facing
slopes than on south and west facing slopes. Therefore, the former
will be wetter longer.

We know, too, that moisture is a factor in the success of
volunteer species which will occupy a slope; and that dry site
species will occupy the upper slopes and that wet site species will
occupy the lower slopes. In the Yellowstone we find that lodgepole
pine germinates quickly on slopes exposed to sunlight, and that fir

and spruce will germinate on duff covered, moist shaded slopes.
The succession of species following forest fires is the same.

CLIMATIC FACTORS:

Exposure to wind, sun and extremes of temperature will affect
available moisture for plant growth. Seed retention and ultimate
germination will depend on the roughness of the slope where slight
cracks and crevices provide harbors for the seed. Mulch will shelter
the seed from the sun's heat, and also will absorb the impact of
rain from dislodging the seed.

The practice of hydroseeding promotes the growth of turf on
slopes, especially in situations where equipment and planting
crews are impractical. Hydroseeders are capable of spreading mixtures
of seed, fertilizers, and mulch simultaneously. Be especially
cautious in the fall of the year...Seed the slopes (the seedbed)
before the ground freezes. Root growth will occur over the winter,
and the degree of erosion will be reduced.

Remember that the lighter colored mulches will reflect the sun's
heat while darker colored mulches will absorb heat. Deep mulches
(three to four inches) will insulate the soil against freezing and
thawing better than will thin mulches (one to two inches). Frost
heave results from alternate freezing and thawing. Voids created
by frost heave cause roots of plants to wither and die. The choice
of mulch materials is important, in that the process of decomposition
extracts nitrogen from the soil. Inorganic mulches (asphalt or
fiberglass) will not deplete soil nitrogen needed for plant growth.

Maintenance:

You will be asked for recommendations for the maintenance of
road slopes. Please remember that slopes steeper than 2:1 are
hazardous to equipment operators, and that wet ditches cause tractor
wheels to sink. Designate areas to be mowed to grass heights of
four inches to reduce browning-off during the summer droughts and
set aside areas as seedbeds for wildflowers...these to be mowed
after the seeds drop in late summer.

Aesthetics:

Vista clearing is a designed operation, not "eye-balling" as
some folks accuse us of practicing. First, decide on what features
you want to interpret along the roadway (the nature of the mature
forest, for instance) and then decide on those features which will
enhance the scenic quality beyond the roadway (the snowpeaks of a
mountain range, for example). Prepare a plan showing the locations
of these "openings" along the roadway. Flag those dominant trees
to be removed. Step back to the motorists' travel path to study
the trees selected. Consider the effects of the scene, the consequence
of removal on the remaining vegetation. Make the final
decision based on your best aesthetic judgment and your knowledge
of silviculture. Vista clearing is a combination of the two arts:
aesthetics and silviculture.

Running the job:

Working over a slope, especially a wet slope, is sometimes
hazardous and sometimes damaging to the slope itself. Removing
deadfalls and loose rock can leave scars, and a fall or a slip of
the foot can cause an injury. Use ropes and gloves when working
on steep slopes... and never work alone!

Be especially careful with handtools and instruct new workmen
in the use of saws, axes, and pulaskies. Gloves, goggles, chaps,
stout shoes, and hard hats are essential.

Controlling traffic along the roadway is necessary to reduce
accidents. Warning signs must be posted at least 500 feet in
advance of the work site so that motorists can slow down, and flagmen
must be stationed to control cars approaching the work site. Safety
for both work crews and motorists is part of the job!

LECTURE 12 - PAVEMENTS

(See Seelye, pages 343 to 345, 370 to 382; Thickness Design,
The Asphalt Institute, College Park, MD; Interim Guide for Design
of Pavement Structures, AASHTO, Washington, D.C.)

Pavements are flexible (bituminous) or rigid (reinforced concrete).
Each has its attributes.

Concrete has the advantage of acting as a rigid slab which distributes
the load over a wider surface area on the subgrade. Because
the structure is rigid, the wheel loads are supported over the occasional
voids and soft spots that develop in the subgrade; the slab
acts like a bridge spanning the underlying voids.

Concrete pavements can be built to closer tolerances than
asphalt (bituminous) pavements because the formwork which contains
the plastic concrete can be accurately installed before the material
is poured. Also, the mixture is easier to control in terms of
hardness, strength, curing, and testing.

Concrete is by definition a mixture of aggregates, cement and
water which in the process of hydration forms a rigid mass of high
compressive strength. It is the property of concrete to be "incompressible"
that makes it a valuable construction material; furthermore,
concrete has a very low coefficient of expansion which
provides structural stability. The problem with concrete is that it
has a very low tensile strength: steel rods, which have a very
high tensile strength are implaced in the concrete mixture to provide
that property. Expansion joints are designed into concrete
structures to control cracks that result from tensile weakness;
otherwise, random cracks would occur as the heated slab cools and
contracts.

The selection of aggregate contributes to hardness, color, and
durability. Crushed granite, for example, will produce harder concrete
than crushed gravel composed of sandstone. The angularity
and distribution of particle sizes are factors of hardness; angular
particles (crushed stone) have a greater mechanical strength than do
rounded particles (gravels). Particles of uniform size are separated
by uniform size voids; graduated sizes are introduced to fill the
voids. Cement is the binder that locks the particles into a mass.

We are finding that calcium chloride applied to melt ice causes
a rapid deterioration of concrete due to the oxidation of the reinforcing
steel within the road slab. The concrete itself appears
to slough, the aggregates break apart, and the steel is finally
exposed. According to concrete people whose opinions I respect,
it seems that in the process of oxidation (rusting), the metal
expands to ten times its original volume. As rusting occurs, the
concrete, having a low tensile strength, is slowly "exploded" away
from the steel. The external crumbling is the symptom of the
interior process taking place in the slab.

The bridge decks you have seen being replaced on the George
Washington Memorial Parkway at Dead Run and Spout Run failed because
of this oxidation process. To prevent the recurrence of the problem
an apparatus was to have been installed which causes a low electrical
current to pass through the reinforcing steel thereby stopping the
oxidation process. The bridge engineers of the FHWA described a
technique tested by the Germans wherein the slab was impregnated
with hot asphalt under pressure in order to seal the concrete against
moisture. I know nothing more about it.

The concrete road slabs are "tied" across the expansion joints
by steel dowels to overcome the tendency of one slab to rise above
the other. Half of the dowel is covered with a sleeve to allow
for expansion between the slabs; the joint is filled with an asphalt-impregnated
fiber or mastic to waterproof the opening.

The thickness of the reinforced slab is determined by the anticipated
weight of vehicles, and by the stability of the subgrade,
and by the quality of the concrete itself. In some situations it
may be more economical to construct a thick slab of soft aggregate
than to build a thin slab of hard aggregate. Availability of
materials can be the determining factor in slab thickness.

CURBS:

I am a strong believer in mountable-type curb 'n gutter. The
curb retains the shoulder, controls drainage on the pavement, and
defines the edge of the pavement. Colored pigment can be added to
the concrete to resemble the color of the local soils; also,
colored aggregates can be selected and the finish exposed to resemble

the local soil. In any case, I prefer concrete with color pigment
added to the mix. Don't use lamp black! It weakens the concrete
and looks ugly. Use inorganic pigments; colors range from black
to buff. Or use an aggregate of proper color...it makes a good
job better.

NOTE: If you are working on defense roadways, be aware of the
requirements for heavy wheel loads. Haunches or grade beams might
be required at expansion joints, especially over soft subgrades.

BITUMINOUS PAVEMENTS:

Bituminous pavements (asphalt) are cheaper to build than concrete
pavements; they are more costly to maintain over the long
haul (time period) but are easier to repair. The riding surface
is smoother because expansion joints are not needed. However,
chuckholes develop with freezing and thawing action. The black
surface resists ice formation but it is vulnerable to damage from
gasoline.

The advantages of concrete versus asphalt can be argued by
people who know more about it than I do...but I like the Colonial,
and the Suitland, and the Baltimore-Washington Parkways because
it's my prejudicial nature.

The Asphalt Institute defines Asphalt as, "A dark brown to
black cementious material solid, semisolid, or liquid in consistency,
in which the predominating constituents are bitumens which occur in
nature as such or which are obtained as residue in refining
"petroleum." (ASTM Designation D8)

The Asphalt Institute defines Bitumen as, "A mixture of hydrocarbons
of natural or pyrogenous origin, or a combination of both;
frequently accompanied by nonmetallic deriviatives which may be
gaseous, liquid, semisolid, or solid; and which are completely
soluble in carbon disulfide."

The key words indicate that asphalt may contain bitumen, and
that bitumen is a mixture of hydrocarbons. Asphalt, then, is that
black semisoft material mined in Venezuela which we use to mix with
oil to make a road.

SURFACING:

Most park roads are bituminous concrete over a crushed stone
subbase; the surface course may be a cold mix or hot sheet asphalt
depending on availability of materials and climate. Big Bend has
much heat, sand, and hard aggregate; Yellowstone has much cold,
travertine, little aggregate. Crushed stone chips are apread over
a tack coat to give the road surface a color and texture which blends
into the immediate landscape hues. The South Rim Drive at Grand
Canyon is surfaced with red chips; the roads at Craters of the Moon
are surfaced with black chips. I prefer crushed gravel to rounded
gravel (of uniform size) because it adheres to the tack coat longer.
The angularity of particles exposes more surface area to be enclosed
in road tar than is enclosed in rounded gravel particles.

Last summer our Park Engineer in Yellowstone used Asphalt
Emulsion rather than road oil in applying a chip seal; the reason
being the high cost of oil and gasoline. It worked as well as oil,
we thought, and it will be interesting to see how the road came
through the winter.

THICKNESS:

The subgrade is critical in the design of pavements. The Soil
Manual which Rob McLeod gave to you in Terrain Analysis contains
a description of tests for soil properties; you'll see the California
Bearing Ratio and other testing procedures. Check those out.

The Asphalt Institute has developed a method of estimating the
necessary thickness of pavements based on traffic volumes equated
to truck axle loads of 18,000 pounds; you can find the detailed
explanations in the Institute's publication, Thickness Design, MS-1.
They classify traffic according to a system which they call IDT
(Initial Daily Traffic). That is the volume of traffic expected
the first year following completion:

• Light traffic is up to 1,000 vehicles/day on two-lanes;
  equates to 10 trucks.

• Medium traffic is 1,000 to 100,000 vehicles/day on two-lanes;
  equates to 100 trucks.

• Heavy traffic is over 100,000 vehicles/day on two-lane or multilane
  roads.

Four examples are given in the text; each is calculated on a
20-year service life, and an annual increase in traffic volume of 3%.

Example 1: A residential street carries 400 vehicles per day, CBR is 4;
requires an Asphalt Concrete Surface of 1.0 inches
over an Asphalt Concrete Base of 5.0 inches.

Example 2: An urban Interstate carries 10,000 vehicles per day;
CBR is 10; requires an Asphalt Concrete Surface of 2.0
inches over an Asphalt Concrete Base of 6.5 inches.

Example 3: A suburban street carries 4,000 vehicles per day; CBR is 3;
requires an Asphalt Concrete Surface of 1.5 inches over
an Asphalt Concrete Base of 4.5 inches over a Subbase
of 8.0 inches.

Example 4: A Parkway carries 8,000 vehicles per day; the road is
restricted to cars, buses and service trucks; requires
an Asphalt Concrete Surface of 1.0 inches over an Asphalt
Concrete Base of 6.0 inches.

An alternate is given for the Interstate where an equivalent
pavement is 2.0 inches, on 4.0 inches, on a 5.0 inch subbase; an
alternate for the Parkway shows 1.0 inches, on 4.0 inches, on a
5.5 inch subbase.

ASPHALT CURBS:

I have a prejudice against extruded asphalt curbs; I don't like
them because auto tires and snowplows leave scars on the surface.
Often the workmanship is poor and the alignment is crooked. Al
Kuehl used to call them "toothpaste curbs"...he was right and is
very much part of my prejudice!

TRAILS:

Before we leave the subject, let me strike a blow for soil-cement
as the better material for hiking and biking trails!
Bituminous surfacing is out-of-place in the backcountry! If you
use it there, I'll hunt you down and make you clean-it-up! Even
on road surfaces, bituminous material is ugly. Cover the stuff
with stone chips or bury it under an inch of dirt...it belongs
under the road surface, not on it.

MIXES:

Road mix is bituminous concrete prepared with a patrol grader
and a spray rig alongside the road; cold mix is prepared in a plant
and spread and compacted at air temperature; hot mix is prepared in
a plant where oil and aggregate are heated before being hauled hot
to the job.

Oil (Bitumen) becomes more viscous with higher air temperatures;
at Death Valley with temperatures of 120+, oil runs like water and
must be blotted-up with sand! At Furnace Creek, the road oil flowed
to the bottom of a vertical sag in the road to the maintenance and
housing area. Try to explain that to the mothers and the school
teacher who stop by the job with fire in their eyes!

Write to the Asphalt Institute and the Portland Cement Association
for their publications. And send for a publications list
from AASHTO. Start your library now...it's a long time building!

BITUMINOUS MATERIALS:

1.

• Requires soils analysis to determine thickness of pavement.

2.

• Asphalt Institute establishes various thickness and spec for
  soils.

3.

• Low Type Bituminous: for wheel loads up to 7000 pounds; life
  up to two years; requires annual seal coat; low cost, high
  maintenance; surface treatment less than 1″ thickness;
  "prime and seal coat: Armor coat"

4.

• Calculate thickness according to Seelye table for "design of
  flexible pavements"; design curves are by Asphalt Institute;
  soils are classified by USDA or USCE

5.

• Selection of Bituminous Material depends largely on temperature!

               

  ---

  7

  
  
  
           

  RT-1 is 60° to 125°	(RT = Road Tar)
  RT-12 is 175° to 250°
  RTCB is 60° to 120°	(RTCB = Road Tar Cut Back)
  SC-0 is 50° to 120°	(SC = Slow Curing Road Oil)
  SC-6 is 400° to 400°
  MC-0 is 50° to 150°	(MC = Medium Curing Cut Back Asphalt)
  MC-5 is 200° to 275°
  RC-0 is 60° to 125°	(RC = Rapid Curing Cut Back Asphalt)
  RC-5 is 200° to 250°
  SS-1&2 is 50° to 120°	(SS = Slow Setting Asphalt Emulsion, AE)
  MS-1 is 60° to 120°	(MS = Medium Setting Asphalt Emulsion, AE)
  RS-1 is 80° to 135°	(RS = Rapid Setting Asphalt Emulsion, AE)

  Asphalt Cement Penetration is hot application from 275° to 400°
  (the higher the number the more viscous the material)

6.

• Types of Pavement:

           

  Type 1		Open type pavement, penetrating macadam, hot or cold, plant mix or road mix of crushed stone and bitumen (coated aggregate)
  Type 2		Dense Mats, mixed in place, plant mix or road mix, aggregates graded coarse to flue and bitumen
  Type 3		Dense graded pavement - Bituminous Concrete, plant mix of aggregates graded coarse to fine with minerals
  Type 4		Dense graded sand pavements, Sheet Asphalt, Plant mix of sand passing #10 to #200 mesh, minerals
  Type 5		Dense Sand Mat, Sand Asphalt, plant mix or mixed-in-place sand passing #4 mesh and bitumen

LECTURE 13 - PARKING AREAS:

DETERMINING SIZE:

The number of parking spaces to be provided is a function of
carrying capacity...that appropriate number of visitors which can
be accommodated within the inherent capability of a land area to
regenerate itself. The carrying capacity divided by 3.5 visitors
per car will give you a reasonable estimate of the total number of
parking spaces to be provided.

Let's look at a trail within a forested area. Say: the density
of vegetation and the alignment will carry groups of five persons
separated at intervals of not less than 500 feet, and that a closer
interval would detract from the quality of enjoyment of an adjacent
group. The carrying capacity would be the resultant of the
length of the trail (5,000 feet) divided by the interval (500 feet)
multiplied by the number of visitors per group (5 persons) for a
total of 50 persons. Observations show that an additional 25% of
that number will be in the parking area at the same time either
starting to hike or returning from the trail. Parking spaces are
needed for 50 plus 25% (say 12) or 62 persons, divided by 3.5
persons per car for a total of 18 spaces. At 300 SF per car, the
parking area would require 5400 sq. ft. of surface and 180 feet of
curb.

Other standards:

• -Offices for 80 employees and 20 visitors at 1.5 persons/car
  require 67 spaces.

• -Visitor centers for 200 visitors at 3.5 persons/car require
  57 spaces plus staff parking.

• -Swimming beaches at 165 SF/person may require 500 spaces
  located 1,000 feet apart (standard from Griner and
  Associates, used at Assateague Island)

• -Marinas are based on 1¼ acres of water per boat; allow parking
  spaces for one-third the number of rental boat slips

• -Amphitheaters are based on 10 SF/person or 3 LF of seating
  per person

(See the BOR publication on space standards for such things as acres
of open space and recreational facilities for various population
centers.)

Dimensions of Spaces:

The ASLA Construction Handbook shows the following critical
dimensions:

• -45° spaces require 9′x 12′- 9″/car, 49′- 8″ curb to curb, or
  316.7 SF/car

• -60° spaces require 9′x 10′- 5″/car, 56′- 6″ curb to curb, or
  296.6 SF/car

• -90° spaces require 9′/car, 58′- 0′ curb to curb, or 261 SF/car

Even though cars today are smaller, there is need to design for
the standard size automobile. It is my opinion that spaces of ample
size are well worth the extra cost in paving; furthermore, parking
areas of ample size allow two-way circulation thereby overcoming
the need to provide circulatory roads. Howland recommends:

• -90° spaces, 10 feet wide, 60′- 0″ between curbs, or 300 SF/car.

• -For single-rank parking areas, I recommend 45′- 0″ between
  curbs with spaces 10′ wide.

Shade Trees:

I recommend planting a shade tree in every fifth parking space
to cool the temperature inside of cars parked under the canopy.
That provides a maximum spacing of 40′x 50′. The alternative is
planting of trees within the median between the ranks of cars. That
provides a maximum spacing of 40′x 70′. Examine the plan and sections
for the spacing recommended and the alternate.

Willow oak is, as you know, the shade tree I prefer. Pin oaks
are not my choice because of the low habit of branching, though
that species is an excellent tree to screen along the periphery.
American elm is the ideal shape and density if you can justify the
choice in the face of Dutch Elm Disease.

Surfacing:

Crushed gravel chips on a tack coat over a medium type pavement
(i.e. 2″ of surface over 4″ of bituminous concrete, over a 5″crushed
stone base) is adequate for parking areas in urban centers. Avoid
smooth hot asphalt surfaces because leaves tend to make the surface
slippery. Striping is a necessary evil to control density unless
numbered posts are used. Parking meters serve the same purpose in
municipal and commercial areas. I prefer posts.

Drainage:

Curb inlets are more efficient than flush grates located in the
middle of parking areas along the centerline. Part of this prejudice
is based on the observation that pedestrians walk along the centerline,
even though walkways are provided in the median. Leaves tend
to build up over flush grate openings and are better collected in
open throats along the curb than in the middle of the pavement.
Also, consider the fact that noise can result from each car driving
over a loose grate when the inlet is located on the centerline.

Curbs versus Wheelstops:

I prefer cast-in-place concrete curbs (with exposed colored
aggregate) to wheelstops which are precast. In natural areas, I
like stone curbs or pressure treated timber, either dimensioned or
cut from logs. (Don't use extruded asphalt...you know my opinion of
that material.) Wheelstops are frequently fixed to the road surface
with reinforcing steel, a material that is too small in diameter to
resist the impact of the wheels, and so thin that it tends to act
like a knife in cutting the surfacing material. Log and timber
curb (consider ties at 6 x 8) can be imbedded in the surface or
placed on the base before the surface course is applied. Log or
timber has greater resistance to the impacts of car wheels than
wheelstops.

CAUTION!!

The maximum slope on parking areas, in section or profile, should
be 6%!! To exceed that gradient is to invite cars to roll downhill.
Some drivers do indeed forget to set the handbrake or to leave the
car in gear. Also, ice can be a problem in maneuvering into and out
of parking spaces when grades exceed 6%.

SPECIAL CONDITIONS:

Overflow parking areas need not be paved when they are only used
occasionally. Overflow parking areas can be inconspicuous. You
might consider stabilized turf rather than pavement. Lay down eight
inches of #3 stone to grade; puddle the voids with topsoil, then seed
with a deep-rooted grass (Kentucky Bluegrass). Be careful to let
the grade of the topsoil be slightly below the surface of the stone.

Campgrounds:

The most efficient layout I've seen for campgrounds is at Grant
Village, Yellowstone which was built to the criteria recommended by
Frank Mattson, a Park Landscape Architect of outstanding ability.
Frank said that campsites should be staggered along the roadway,
one site per 35 LF of road; that parallel roads should be 125 feet
between centerlines, and that a two-way throat should connect the
one-way loop with the main campground road. Also, that three types
of sites should be provided in equal proportions to accommodate
tents, trailers, or RVs: spurs for back-ins, pull-throughs, and
pull-offs. That's what was built and it functions well after 23
years of intense use.

Campground sanitation requires that the distance from the
farthest site to the nearest comfort station will not exceed 300
feet, and that comfort stations should not be placed farther apart
than 600 feet.

Bus Parking:

Let buses be directed to the right in turning into spaces in
order to provide access to the loading door; otherwise the doors
are blocked by adjacent buses in turning to the left. I recommend
a radius of 50 feet to the outside curb, a turning lane of 15 feet
between curbs, parking spaces 12 feet wide, and a stabilized inside
turf shoulder 2 feet wide.

Amphitheaters:

Locate approach roads and parking areas so that head lights are
directed away from, rather than toward, the seating area and projection
screen. Headlights can be distracting nuisances during
after-dark interpretive programs. Provide low-level standards to
light the trail to the parking area after the program is over.

Trailer Parking at Boat Ramps:

The most critical features in the design of public boat ramps
are the width and gradient of the ramp itself. Let the ramp be
40 feet wide and the grade 14%. That width will serve 3 boats at
one time (all boats seem to leave and return at the same hour).
That gradient will permit most boats to float free of a trailer

without submerging the towing vehicle. Also! Provide a surface of
high traction, especially where algae is prevalent! Imagine yourself
a novice driver towing a new boat and trailer. You approach the
shoreline driving toward the ramp; you turn right until you see the
boat and trailer reflected in the mirror on the car door. You then
back toward the ramp, constantly watching the reflection in the mirror,
until your boat and trailer are aligned with the ramp. You slowly
back down the incline until the boat is bouyant. Then you stop, set
the handbrake, turn the engine off, set the parking gear, and leave
the car to unlash the boat from the trailer. After you have secured
the boat to the pier, you drive the car and trailer to the parking
area—they remain there all day.

After a day of fishing, you return to the pier, secure the boat,
and drive the car and empty trailer back to the ramp. This time you
watch the trailer reflected in the mirror, then back down the ramp
until the trailer is submerged. You stop, set the handbrake, turn
the engine off, set the parking gear, and leave the car to load the
boat on the trailer. Then you drive straight up the ramp and away.

All quite complicated in description, but the simplest way I know
to design a ramp and parking area for the boater who uses the place
ten times a year.

Picnic Areas:

Most of us would prefer to find a table and fireplace ten feet
from the trunks of our cars. Others prefer to carry their picnic
baskets to a secluded spot a hundred yards away. And there are groups
of children who alight from school buses, then rush to the playfield
and later assemble under a shelter for a group picnic. A well-designed
picnic area will satisfy all of those visitors. Locate
the road to serve the sites rather than the sites to fit the road.
Allow 15 sites to the acre in forested areas and provide comfort
stations in conspicuous places beside the roadway for visitors' convenience
and for easy maintenance. Groups of five parking spaces
staggered along the road with bus parking near the playfield will be
efficient. (The publication, Guide for Highway Landscape and Environmental
Design, shows some suggested layouts for roadside rest areas.
See also the NPS publication Park Structures and Facilities available
in our library.)

Maintenance Areas:

The perpendicular distance between the bay doors of storage and
equipment buildings (or fences) should be not less than 100 feet
to provide turning radius for service trucks and snowplows and some
area to stockpile snow. The paving surface should be dark to melt
snow and smooth enough to be cleaned with a firehose. The pavement
on the approach road and in the yard should be about 3″ of surface
on 4″ of bituminous concrete on 8″ of crushed stone base course.
Drainage inlets should be along the centerline to carry water away
from the buildings and to insure that fuel oil and gasoline spills
will be directed away from stored vehicles and buildings.

Turning Radius:

Large trucks including semi-trailers need an outside turning
radius of 65 feet. They can, by backing-up, maneuver within the
100-foot opening of a maintenance yard. Plot the maneuvers on paper
to locate gas pumps, fences, gates, etc. It is not economical to
design maintenance yards for openings greater then 100 feet. Provide
parking areas for large vehicles and employee cars outside of
the yard.

Buses and two-axle trucks need an outside turning radius of
50 feet; plot their maneuvers on paper, too.

Standard-size automobiles need an outside turning radius of
28.5 feet; it is necessary to plot their maneuvers as you do for
buses and trucks.

Treat Ambulances, Firetrucks, and Service vehicles according to
dimensions shown above.

LECTURE 14 ROAD CONSTRUCTION

This lecture is an experiment. We will test the proposition that
the usual lecture in Road Construction can be combined with a lesson
in Critical Path Method (CPM)

Some years ago, I arranged a contract with a Mr. Dominic to
conduct a training session for our people in Design and Construction
so that we might improve our record in meeting deadlines. Mr. Dominic
was retired from the General Services Administration where he
enjoyed a good reputation for getting jobs done and buildings completed
on time.

He told this story: a successful private design office had just
finished a large job on schedule and was enjoying a lull in the
momentum of the office. Suddenly several jobs went bad and the staff
was busy putting handles on projects that were underway. Just as
quickly, the office failed and the principals met to ask why. At
the moment of the lull, a critical action was overlooked! It wasn't
planned to happen that way.

Mr. Dominic's two-day training contract was an education in
controlling our work. We met deadlines and learned that CPM can
be applied to many cases.

Suppose you are working for Jones and Jones, Landscape Architects
based in Charlotte, N.C.. You have just been awarded a contract for
professional services to design and supervise the construction of a
road over the Blue Ridge from Stanardsville to Elkton. Your firm
is to be paid from Federal-Aid funds with the requirement that Superintendent
of Shenandoah National Park must approve all phases of
the work. You are named Project Supervisor for the job.

Here's how CPM works:

Step 1.

• List every activity that must happen to build the road.

2.

• List the sequence in which these activities must occur.

3.

• Assign the number of days needed to complete each activity.

4.

• Diagram the sequence showing the number of days assigned.

5.

• MONITOR THE PROJECTS DAILY!

Let's start by listing the activities that must happen, Step 1.

                                                                           

STEP ONE	STEP TWO	STEP THREE
Prepare location plan for public hearings	2	3 days
Obtain traffic counts, aerial photos, maps	1	5 days
Draft EIS and submit to VDHT, FHWA and NPS	6	14 days
Advertise and conduct public hearings 1 & 2	4 & 9	30 days + 30
Prepare alignment and location studies	3	21 days
Review public comment, revise alternatives	5	21 days
Invite on-site recon of prelim centerline	13	1 days
Walk prelim line with VDHT, FHWA, NPS	14	5 days
Survey approved centerline, take X-sections	15	90 days
Transmit final EIS to VDHT, FHWA, and NPS	10	14 days
Acquire R.O.W.	12	2 years
Prepare prelim design and cost estimate	8	180 days
Obtain soil borings	7	30 days
Submit prelim design and estimate for app'l.	11	2 days
Send notices of intent to advertise in CBD	17	2 days
Prepare construction drawings, spec, estim.	16	180 days
Request wage rates	18	2 days
Obtain work order	19	2 days
Mail plans and specs to prospective bidders	20	60 days
Open bids, select successful bidder	21	2 days
Issue notice to proceed	22	2 days
Set limit-of-grading stakes	23	60 days
Clear and grub within slope stakes	24	180 days
Set centerline and grade stakes	25	90 days
Rough grading and excavation, lay culverts	26	120 days
Compaction and final grading	27	90 days
Install culvert ends, subsurface drainage	28	60 days
Lay subbase, grade shoulders and ditchline	29	60 days
Seed and fine grade slopes	30	60 days
Lay base course and surfacing	31	90 days
Erect signs and traffic control devices	32	30 days
Hold prefinal inspection, make punchlist	33	5 days
Final clean-up	34	30 days
Final inspection and payment	35	5 days
Submit as-builts and completion report	36	45 days
TOTAL	2351 days = 6.44 years
CPM	1408 days = 3.86 years

THE SEQUENCE OF ROAD CONSTRUCTION

Note: Public hearings are required to be conducted by the States
for funding under Federal Aid for Highways.

PHASE I: PRE-PLANNING

• -Establish need through highway system plan; conduct origin
  and destination studies.

• -Establish purpose - primary, secondary, urban

• -Establish criteria - design speed, gradient, access, capacity, et

• -Establish route - examine land ownerships, costs of R.O.W.,
  aerial surveys

• -Conduct public hearings - submit report of hearings to FHWA

• -Draft EIS or negative declaration - project is or is not
  major action.

PHASE II: PRELIMINARY PLANNING

• -Prepare location studies

• -Flag "P Line" with Team - engineer, biologist, manager

• -Conduct route survey

• -Prepare alignment studies - notify other authorities of proposal
  - submit draft of EIS to other agencies

• -Conduct public hearings - submit report of hearings to FHWA

• - Receive final approval of PS&E and authorization of funds

PHASE III: PROJECT PLANNING OR PS&E (Plans, specs & estimates)

• -Note: FHWA calls phase "Plans, Surveys & Engineering"

• -Prepare construction drawings, specifications and final estimates

• -Conduct field review (plans in hand) with FHWA representative

• -Receive final approval of PS&E and authorization of funds

PHASE IV: BIDS AND PRE-CONTRACT

• -Send notices of intent to advertise to journals, CBD (Commerce
  Business Daily), newspapers, etc. - request wage rates

• -Advertise - mail plans and specs to prospective bidders

• -Open bids - examine prices, bid bond, reputation of bidders, etc.

• -Award contract to successful bidder - Contracting Officer
  signs contract - hold pre-construction conference

• -Issue Notice to Proceed.

PHASE V: CONSTRUCTION

• -Set slope and grade stakes; clear and grub site - grading
  and excavation - demolition of structures

• -Stake-out centerline and subgrade stakes - install drainage
  structures and lighting

---

4





• -Grade ditches and final grading of slopes

• -Lay down subbase material - grade shoulders

• -Install curbs - rake to subgrade, spread topsoil, seed
  and plant

• -Lay down base course - lay down surface course, stall lighting,
  erect roadside signs

• -Hold pre-final inspection - write up punchlist - final finishing

PHASE VI: FINAL INSPECTION

• -Walk job with FHWA representative, the contractor, his superintendent,
  the inspector or project supervisor may be yourself,
  and the maintenance supervisor

• -Inspect job to see that all items on punchlist are corrected
  and the work is completed

• -Check all quantities by measurement and recommend for payment -
  settle all possible disputes or reasons for later claims

• -Notify contractor of acceptance

PHASE VII: FINAL PAYMENT AND COMPLETION REPORT

• -Recommend final payment by agency or owner - submit as-builts
  (drawings) and completion report for record of work

• -Note: Job log is not part of contract documents but may be
  used as evidence in court.

LECTURE 15 - MAINTENANCE

As you know, 01'Ben started work on a road crew in the CCC and
then as a gardener in Maintenance and Horticulture, National Park
Service. I'm still a Maintenance Guy!

One fourth of all highway funds go for maintenance; these costs
will increase as the Interstate System ages. According to Clarkson
Oglesby in his book Highway Engineering, it takes 3.1 persons to
maintain one lane-mile of rural roads compared to 37.4 persons on
city streets. He cites costs for 1970: $4.3 billion of the
$18.8 billion highway expenses were spent for maintenance. Traffic
services (the cost in wages for control devices and flagmen) cost
12%; operation of toll roads and bridges cost 8%; snow removal and
sanding cost 14%; the remainder, 61% was spent for road and roadside
maintenance. Add to that the growing trend that in tort cases, the
Courts (justifiably) are holding maintenance personnel responsible
for injuries to motorists.

Working Relationships:

You may find yourself called upon to advise maintenance people
about many matters of aesthetics important to their operations.
If you accept a job in maintenance, you will be sharing much time
with a civil engineer in the office and in the field. That person
will be as dedicated to the job of maintaining the pavement and
structures as you are to maintaining the roadside. You may well be
the first landscape architect that person has worked with, simply
because civil engineers far outnumber landscape architects. Be
patient! You'll get more done together than either of you will
working alone! Remember, that we have a tradition of working together
since 1926 when the interbureau agreement was signed. We share a
proud history.

Roadside Vegetation:

The difficulty with road construction, as we've talked before,
is that we build a seedbed on both sides of the pavement that must
indeed be managed. That management of roadside vegetation is
usually the job of the landscape architect and your professional
judgment is expected for controlling volunteer seeding of "weeds."
Look for the seed source; examine the soil surface on which the

seeds germinate. You may not have an immediate solution, but strive
for a natural method of control rather than a typical method. If you
don't respond, herbicides and asphalt mats will be used to solve the
"problem." The task you face most often is to understand the situation
quickly and to offer a solution based on natural processes
rather than artificial methods.

De-icing Chemicals:

Calcium chloride is slowly causing widespread damage to downstream
habitat as well as roadside vegetation. Research is warranted
to determine the effects of calcium chloride on the corrosion of
metals in concrete, on bridge rails, and on plant materials. Two
million tons of salt were laid down annually in the mid-sixties
according to Oglesby; every ton was handled by maintenance people!
And we will be concerned about the effects of that practice until a
substitute material can be found. In my judgment, the marketing and
using of salt were irresponsible in the beginning, and will continue
to be so until acceptable substitutes are developed through research.

Maintenance Plans:

You are required to prepare plans for the maintenance of the
roadside: where to mow, where to permit the volunteers to occupy
slopes, where to cut and maintain vistas, and the schedule for
mowing to insure the seeding of wildflowers. You can help if you
will show the location of all culverts, drop inlets, and subdrains
on your plan for maintenance. On the drawing, include a list of all
drainage structures located by centerline stationing and the road
distance measured on the odometer so that crews can find the structures
from the truck. Remember that most employees are seasonals
who don't know where things are. When the boss can't be reached
on the radio, seasonals are frustrated by the lack of information.

Ditches:

One of the greatest causes of road failures is our neglecting
to clean ditches. Debris and soil build up over flush grates to
the depth that the inlet is obscured and is eventually "lost."
The last person who knew its location is now at Everglades and the
new R&T foreman didn't get the word. Deep or V-shaped ditches are
given little maintenance because it's difficult to work the ditchline

with machinery. Be an advocate for broad shallow ditches. They are
safer and easier to maintain.

Inspection of Culverts:

Include in your maintenance plan a program for the annual inspection
of culverts showing the length and direction of the pipe
and any problems you know about. We lost a section of West Beach
Drive when a culvert broke under a heavy fill....and you saw the
photograph of the earth-slide we had at Yellowstone when a culvert
broke. Storms and rapid snow melt can cause runoff volumes which
exceed the design capacity of structures and culverts. Observe
the warning signs: bulges at the toes of slopes, debris left by
highwater over the tops of culverts, erosion on streambanks, and the
fans of sediments deposited below the outfalls of culverts. Spend
a day riding the roads with the crew boss...ask where changes are
occurring and what it was like five years ago.

Inspection of Bridges:

In writing a maintenance program, require that bridges be inspected
annually! The frequency of structural deterioration in
recent years is alarming! We see the corrosion of incompatible
metals on bridge rails and the effects of salt on concrete bridge
decks too late to employ routine repairs. By the time we discover
the effects, the "damage" requires replacement. Turkey Run, Spout
Run, 14th Street Bridge, even the pier nosings under Key Bridge were
so far deteriorated before the damage was discovered that the structures
were no longer safe. Again, institute a program for annual
inspection by structural engineers. Write a contract for their recurring
services. Put that on your checklist. See that it happens!

Resurfacing:

We've been finding a loss of friction on surfaces worn smooth
by long use. Heavier wheel loads and studded tires are causing increased
damage to thin surface and base courses, especially on roads
constructed for lighter traffic before urban growth took over the
rural roadways. Examine the depth and condition of pavement and
subbase when you are writing maintenance programs; surface evidence
alone is an insufficient indicator.

Uniform Traffic Control Devices:

Obtain a copy of the FHWA publication, UTCD for standards showing
sizes of signboards and alphabets, heights of letters for given
speeds and distances, and locations and construction details. You'll
need a copy. Road signs are much like street graphics which landscape
architects design; the scale and sites are larger. The book
shows requirements for lighting, traffic lights, striping, placement
of sign standards, etc.

Roadside Parking:

Look at the condition of shoulders and ditchlines. "Bootleg
parking places" develop where motorists stop their cars to photograph
a herd of elk or a mountain reflected on the lake, or just
to fish. You must decide whether to pave it (and make it legal) or
to barricade it for reasons of safety. Be especially careful that
sight distance is adequate if you let it stay!

Overlooks:

In placing guardrail or parapets at overlooks, let the setbacks
from the edge of pavement be ample so that motorists can park safely
or close enough to the pavement edge to prevent their parking...we
can't have both! And don't locate parking areas on one side of the
pavement where cars must drive across the opposing land unless
there is ample sight distance in both directions! I believe it's
safer to provide a deceleration lane and a 90° throat than to bring
cars into a long acute angle approach of insufficient length to
slow down.

Relocation:

Road improvements are absolute mistakes if the new curves signal
higher speeds. Example: a curve regarded as "too sharp" is "flattened"
for improvement. The easier improvement may have been to
remove vegetation on the inside of the curve to improve sight distance,
and then plant several trees along the outside to warn drivers
that the road ahead changes direction. As we learned in the definition
of assumed design speed, drivers' perceptions of what's ahead
influences speed. Reconstructing a sharp curve to make it safer can
signal that speed may be increased. Again, let uniformity and gradual
increases in design speed be your watchwords...inconsistencies

and surprises increase the numbers of accidents! Know that accidents
will occur; it is your job to predict where they are most
likely to happen and design for the safest conditions possible.

Traffic Control Devices:

Civil engineers have responsibility for maintaining traffic
lights, overseeing the accident recording procedures, striping centerlines,
and gathering traffic data; all this from a plan designed by
a traffic engineer. You will be required to know about those tasks
because you'll be asked to assist. Learn what it costs to do those
jobs so that you can write realistic estimates when the civil is
away. Be aware of traffic hazards and report them immediately!
We all have responsibility for safety.

Roadside Markers:

Markers are by nature very specialized communicators. They tell
the motorists the stories of historical events, the names of streams
and the animals who need them for water, and of the people associated
with a place. Signs require your knowledge and sensitivity for a
place, as well as your design talent. You can order stock signs
from Seewah Studios or have them make it from your design. Or you
can have it done in the signshop or by contract. Some prison industries
will make signs under a reimburseable account. My advice is
to design your own signs...you'll be happier with the result.

Maintenance of Roadsigns:

Roadsigns can be of four separate and functional types:
directional signs point the way of the travel path; informational
signs tell the distance to places ahead; regulatory signs tell where
to stop, yield, or slow down and the speed limit; interpretive signs
tell of the features along the way to help motorists enjoy the experience
of the landscape. More time is spent defending the roadsides
against additional signs than in designing signs. You will be asked
to approve all sorts of regulatory signs: "no parking, no standing,
no fishing, don't walk, don't run, don't picnic,..." All negative
messages emanating from concerns for law enforcement. Defend the
visitors! They own the place.

Defend also the existing sign themes when you are pressured to
adopt the current trends. We've been pressured to adopt the brown

metal reflective signboards and to remove the long established theme
of routed letters on wood. I believe that Yellowstone, the world's
first National Park, should keep its traditional themes in signs,
architecture, and roadside interpretation.

Instruct signshop people to avoid varnishes mixed in stains
and signboard-paints. The varnish reflects light and thereby blurs
the reflective forms of the text. See, too, that mud and dust are
cleaned from the beaded letters for brightness at night. The signs
are on the roadsides communicating their messages 24 hours a day.
Treat them well!

International System of Sign Symbols:

The SSS was a joint effort between landscape architects of Parks
Canada and our Service to build signs that would be understood by
foreign visitors. Doc Savage of Ottawa and Bill Rosenberg of Washington
worked out the methods; Judy Babb designed the symbols.
(Larry Quarrick will give you handouts of the symbols; you'll find
them helpful.)

Assimilation:

As park roads are swallowed up by the street and highway systems
of the cities and states, so too are signs and symbols. In 1953 when
working on the final phases of the Baltimore-Washington Parkway,
I presented a design for green signboards with white lettering to
distinguish the Parkway from the adjacent streets and highways.
The engineers of the Bureau opposed the use of green because it
lacked the contrast of standard black and white signs. We had one
made in our signshop and installed it as an experiment. People
from 3M saw it and offered to make a sample using their new product
called Scotchlite, a reflective signboard material. That was the
beginning of the green background signs you see on the Interstates
today.

The same thing happened with the long map-like arrows and circles
you see at interchanges. Tommy Herr designed the first sign of that
type for the traffic circle on the Virginia side of the Memorial
Bridge. The International Symbols developed for parks met the same
success...you can't keep exclusive rights to a good idea!

Scouting Problems:

Lack of maintenance shows up first in the amount of litter along
the roadside. The next sign is the failure of the road shoulder at
the pavement edge. (Maintenance people will say they've been "pickin'
sanitation and fillin' ruts.") Look to see where their time is being
spent. If they have been rebuilding an obsolete disposal system or
repairing a fault in the design of a facility, it shows up first in
the maintenance of the roadside.

Faults in design cost hours of labor and equipment time which
would best be spent in maintenance. As I've told some of you, when
you are called on to advise a client on improving a maintenance
operation, pay your respects to the manager in the front office, then
go to the maintenance foreman to learn where the problems are. Chances
are that the manager moving up in the company has been there several
years...the guy in the maintenance yard has been there twenty. He
knows where the valve boxes are and can tell you where he steals topsoil
and culvert pipe. He's the most under-rated person in the place
and has more workable ideas than the manager even suspects.

Performance Standards:

There are two keys to managing a maintenance operation: the first
is to Manage by Objective; the second is to measure results according
to Performance Standards that say, "the level of roadside maintenance
will be acceptable when..." and the standards are spelled out.
Examples: ditches are acceptable when there is no evidence of erosion;
when ruts caused by tire tracks off the pavement are raked-out
and seeded within two days; when roadside planting contains all of
the trees that have survived or been replaced as shown on the approved
planting plan; when drop inlets are cleared of debris within a week
of a summer storm; and so on...

Maintenance is the subject of a course in itself. May some of
these thoughts be useful to you.