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Bridges & Structures



River Engineering for Highway Encroachments

In the United States, the average annual damage related to hydraulic problems at highway facilities on the Federal-aid system is $40 million. Damages by streams can be reduced significantly by considering channel stability including: (1) lateral bank erosion; (2) degradation and aggradation of the streambed that continues over a period of years, and (3) natural short-term fluctuations of streambed elevation that are usually associated with the passage of floods.

The Federal Highway Administration document "Highways in the River Environment - Hydraulic and Environmental Design Considerations" was first published in 1975, and is now issued as River Engineering for Highway Encroachments: Highways in the River Environment, Hydraulic Design Series No. 6 (HDS-6). In HDS-6, hydraulic problems at stream crossings are described in detail, and the hydraulic principles of rigid and moveable boundary channels are discussed. This document has proven to be a singularly authoritative document for the design of highway associated hydraulic structures in moveable boundary waterways. Topics discussed in this document are: sediment transport, natural and human induced causes of waterway response, stream stabilization, hydraulic modeling and computer applications, countermeasures, and case histories of typical human and natural impacts on waterways.

  • FHWA Publication Number: NHI-01-004
  • Publication Year: 2001

The PDF file(s) can be downloaded at no cost, there are no free copies of the printed materials. However, printed copies are available for purchase at the NHI store: https://www.nhi.fhwa.dot.gov/training/nhistoresearchresults.aspx?topicnum=135 (look for "REFERENCE MANUAL" under the Type column).

Updated: 11/07/2022
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