The bridge should be centered on the main channel portion of the entire floodplain. This may mean an eccentricity in the location with respect to the entire stream cross section, but allows for better accommodation of the usual and low flows of the stream.

The bridge waterway opening should be designed to provide a flow area sufficient to maintain the through-bridge velocity for the design discharge no greater than the allowable through-bridge velocity.

The headers and interior bents should be oriented to conform to the streamlines at flood stage. Standard skew values of 15°, 30°, and 45° should be used where feasible. The piers and the toe of slope of the header must be located away from deep channels, cuts, and high velocity areas to avoid scour problems or interference with stream low flows.

Consider including either relief openings or guide banks if the intrusion of either or both roadway headers into the stream floodplains is more than about 800-feet.

Existing vegetation should be incorporated into the overall bridge plan. Where practicable, trees and shrubs should be left intact even within the right-of-way. Minimizing vegetation removal also tends to control turbulence of the flow into, through, and out of the bridge.

For some configurations, roadway approaches may need to accommodate overflow. Such overflow approaches allow floods that exceed the design flow to overtop the roadway, thereby reducing the threat to the bridge structure itself. Protection of the approaches from overflow damage should be considered.