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	Memorandum
U.S. Department of Transportation
Federal Highway Administration

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: http://www.fhwa.dot.gov/engineering/hydraulics/software/hy8/.

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 CommentsOnHY8@dot.gov. 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 http://www.pooledfund.org/Details/Solicitation/1222.