Highways in the Coastal Environment

Hydraulic Engineering Circular No. 25
June 2008
A technical advisory panel oversaw the development of this document. Members of that panel
were Kevin Bodge, Billy Edge, Dave Henderson, Rick Renna, and J. Richard Weggel.
This is the second edition of HEC-25. This second edition is a new document with a new title.
The authors of the first edition, entitled “Tidal Hydrology, Hydraulics and Scour at Bridges,” were
L.W. Zevenbergen, P.F. Lagasse, and B.L. Edge. This second edition incorporates and
presents more comprehensive discussions of highways in the coastal environment.
A number of faculty and students at the University of South Alabama provided input into this
document including Qin “Jim” Chen, Lauren McNeill, Bret Webb, Caren Reid, Patrick Keith, Joel
Richards, and Jason Shaw.
The majority of this document was written by Scott L. Douglass, Professor of Civil Engineering
at the University of South Alabama. The project manager, Joe Krolak, FHWA Office of Bridge
Technology, provided some significant contributions.

The purpose of this HEC-25 document is to provide guidance for the analysis, planning, design
and operation of highways in the coastal environment (HICE). The focus is on roads and
bridges (highways) near the coast that are always, or occasionally during storms, influenced by
coastal tides and waves.
This document is intended to be a reference guidance document for Federal Highway
Administration (FHWA), State Departments of Transportation (SDOT), the American Association
of State Highway and Transportation Officials (AASHTO), consultants to these organizations,
and others.
This is nominally the second edition of HEC-25. The first edition was entitled “Tidal Hydrology,
Hydraulics and Scour at Bridges” and reflected results of a SDOT pooled fund study
investigating coastal scour. This second edition is a completely new document and incorporates
and presents more comprehensive discussions of the coastal environment.
Nationally, there are few transportation (and specifically highway related) documents that focus
on the coastal environment. The existing guidance most similar to this document is a Chapter of
the “Highway Drainage Guidelines” published by AASHTO.1 This HEC-25 HICE document
provides additional details on many of the topics discussed in those AASHTO guidelines.
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