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DOT LogoMemorandum
U.S. Department of Transportation
Federal Highway Administration

Subject: ACTION: Distribution of HY-8 Culvert Hydraulic Analysis Program, version 7.3
Date: 10/16/2012
From: /S/ Original signed by Thomas Everert for
M. Myint Lwin, P.E., S.E.
Director, Office of Bridge Technology
In Reply Refer To:HIBT-20
To: Federal Lands Highway Division Engineers
Division Administrators
Directors of Field Services

The FHWA Offices of Bridge Technology and Technical Services are pleased to announce the release of version 7.3 of the HY-8 Culvert Hydraulic Analysis Program (HY-8 7.3). HY-8 7.3 is posted in the Office of Bridge Technology's Website and is now available for downloading at:

HY-8 7.3 expands the capabilities to analyze special hydraulic situations and culvert shapes and includes improvements to make the program run more smoothly and efficiently. New features:

  • Analysis of hydraulic jumps that form within the culvert barrel
  • Broken back culvert profiles for all HY-8 barrel shapes
  • User selection of individual analysis discharge values
  • Horizontal and adversely sloped barrels
  • Special shapes like concrete open-bottomed arches and circular embedded culverts
  • Entrance losses due to mitered concrete pipe and combinations of concrete prefabricated box barrel dimensions, fillets and inlets (i.e. the South Dakota Prefabricated RCB culvert)

HY-8 7.31 comes with a user's manual (accessible through the HY-8 Help Menu) and a Quick Start Guide, which provide users with an overview of basic software operations and features. The technical methods applied in HY-8 are based on the most recent third editions of FHWA publications: "Hydraulic Design Series 5: Hydraulic Design of Highway Culverts" (HDS-5), and "Hydraulic Engineering Circular 14: Hydraulic Design of Energy Dissipators for Culverts and Channels" (HEC-14).

Please note that as per the HY 8 download agreement that FHWA does not provide user assistance or support for this software. Please send all technical issues to FHWA will collect and periodically address technical comments and any bug fixes and reply, as appropriate, back to requests through this email box.

Future planned enhancements to HY-8 include analysis of flared end sections, a hydrographic routing procedure, and an Aquatic Organism Passage design procedure based on the FHWA publication, "Hydraulic Engineering Circular 26: Culvert Design for Aquatic Organism Passage" (HEC-26), First Edition, October 2010.

Cc: FHWA Hydraulics Engineers

1 Funding support for the development of HY-8 Version 7.3 was provided by the Transportation Pooled Fund Program. For details see

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Updated: 10/16/2012

United States Department of Transportation - Federal Highway Administration