FHWA HEC-18 (Fifth Edition)

Anyone involved in Bridge Scour Analysis must be completely familiar with the FHWA Bridge Scour guidance.
This circular documents the equations used in the FHWA Hydraulic Toolbox and guidance for using them.
Evaluating Scour at Bridges, Fifth Edition

FHWA 2D Hydraulic Bridge Modeling

Federal Highway published a document with some guidance and best practices for 2D hydraulic bridge modeling. 
Two-dimensional Hydraulic Modeling for Highways in the River Environment Reference Document

This document includes a lot of useful modeling content, but it is not up to date on HEC-RAS' capabilities.
An updated version of the HEC-RAS entry for Table 2.2 is included below:


SMS/SRH2D Video Tutorial 

SMS and SRH2D have had tools that export 2D hydraulic data to the Hydraulic toolbox.

These tools are slightly different.  They do not work exactly the same way the HEC-RAS tools work.

But this video by Scott Hogan who helped develop those tools, and advised on the HEC-RAS tools, includes some useful context and tips on how to set up a bridge scour analysis.