This document is the fifth edition of HEC-18. It presents the state of
knowledge and practice for the design, evaluation and inspection of
bridges for scour. There are two companion documents, HEC-20 entitled
"Stream Stability at Highway Structures," and HEC-23 entitled "Bridge
Scour and Stream Instability Countermeasures." These three documents
contain updated material from previous editions and continued research
by NCHRP, FHWA, State DOTs, and universities. This fifth edition of
HEC-18 also contains revisions obtained from further scour-related
developments and the use of the 2001 edition by the highway community.
The major changes in the fifth edition of HEC-18 are: expanded
discussion on the policy and regulatory basis for the FHWA Scour
Program, including risk-based approaches for evaluations, developing
Plans of Action (POAs) for scour critical bridges, and expanded
discussion on countermeasure design...