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.
