Crossing Problems

There are a number of ways for a road to cross a river or stream. These include bridges, fords, open-bottom or arch culverts, box culverts, and pipe culverts. Depending on the type of crossing, its size, method of installation, and maintenance, a road crossing may have many or relatively few adverse impacts on a river or stream ecosystem.

The movement of organisms within rivers and streams is an important ecological process that can be significantly affected by road crossings. There are a variety of ways that crossing structures can impede or prevent the movement of animals.

Inlet or outlet drop

• Physical barriers
• Excessive velocities
• Insufficient water depth
• Turbulence
• Absence of bank edge
• Discontinuity of channel substrate