Hydraulic Engineering Circular

2 primary works

Evaluating Scour at Bridges - Fifth Edition

by U S Department of Transportation

Published 3 November 2015

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...

Stream Stability at Highway Structures - Fourth Edition

by U S Department of Transportation

Published 4 November 2015

This document provides guidelines for identifying stream instability problems at highway stream crossings. It is an update of the third edition published in 2001. The HEC-20 manual covers geomorphic and hydraulic factors that affect stream stability and provides a step-by-step analysis procedure for evaluation of stream stability problems. Stream channel classification, stream reconnaissance techniques, and rapid assessment methods for channel stability are covered in detail. Quantitative techniques for channel stability analysis, including degradation analysis, are provided, and channel restoration concepts are introduced. Significant new material in this edition includes chapters on sediment transport concepts and channel stability in gravel bed streams, as well as expanded coverage of channel restoration concepts.