Is future lateral movement of the channel expected to occur at the bridge?

The stream morphology report should define the channel lateral movement zone (CLMZ) at the bridge. Evaluate scour for each bridge element within the CLMZ as follows:

PIERS:

Assume that the channel will move into the pier.

Use these values in the local pier scour module to estimate total pier scour for the condition of channel movement into the pier.

ABUTMENTS:

If the channel is already at the abutment, use the ABSCOUR computations for existing conditions.

If the channel is not at the abutment, but the abutment is within the CLMZ, assume that the channel will move into the abutment. Determine the following parameters from the ABSCOUR printout for the channel for existing conditions:

If the abutment is to be protected with riprap, evaluate abutment stability using the procedure described in Chapter 11 and the contraction scour elevation determined above.

If no abutment scour countermeasure is planned, evaluate abutment stability for total abutment scour using the procedure and the input parameters listed in the Utility Module under Abutment Scour with Future Channel Movement.