HY8:HY-8

HY-8 Versions 3.1, 4.1, and 6.0 were developed by Philip L. Thompson and were provided to the Federal Highway Administration (FHWA) for distribution. HY-8 Versions 1.1, 2.1, and 3.0 were produced by the Pennsylvania State University in cooperation with FHWA. The HY-8 Versions 3.0 and earlier versions were sponsored by the Rural Technical Assistance Program (RTAP) of the National Highway Institute under Project 18B administered by the Pennsylvania Department of Transportation. Version 6.0 (Energy, HYD and Route) was produced by GKY and Associates under contract with FHWA.

Version 7.0 of HY-8 were developed under the direction of Jim Nelson, Rollin Hotchkiss, and Christopher Smemoe at the Environmental Modeling Research Lab at Brigham Young University in cooperation with FHWA. The primary purpose of version 7.0 was to provide Windows-based graphical user interface (GUI) for the same hydraulic calculations performed in version 6.1 of HY-8. In the course of the development all program culvert modeling functions were translated from Basic to the C++ programming language. Several minor bugs in version 6.1 were corrected in HY-8 version 7.0. Versions 7.1, 7.2, and 7.3 of HY-8 were incremental updates in which several new features were included and several bugs were fixed. Besides bug fixes, the following new features were added to HY-8 7.1 and 7.2:

1. Energy dissipation calculators
2. A new culvert shape/coefficient database
3. The ability to model buried (embedded) culverts
4. The Utah State University exit loss equation was added as an option when computing outlet losses
5. Modeling of plastic pipes
6. Research was conducted relating to sequent depth computations for hydraulic jump computations
7. Several improvements and fixes were made to the HY-8 report generation tools.

Christopher Smemoe and Eric Jones at Aquaveo (LLC) developed HY-8 7.3 with help from Brigham Young University's Rollin Hotchkiss and Phillip Thompson (retired from FHWA). The following new features were added to HY-8 7.3:

1. The profile computation code was rewritten to increase program stability and efficiency
2. Capability was added to model hydraulic jumps and their lengths in culverts
3. Capability was added to model broken back culverts and hydraulic jump locations/lengths in broken back culverts
4. Ability to model horizontal and adverse slopes was added
5. Two new culvert types were added to the culvert shape/coefficient database: Concrete open-bottom arch (CON/SPAN) and South Dakota prefabricated reinforced concrete box culverts

HY-8 automated the design methods described in HDS No. 5, "Hydraulic Design of Highway Culverts", FHWA-NHI-12-029 and in HEC No.14, FHWA-NHI-06-086. Version 6.1 is the last version of the MS-DOS program that was distributed. Hydrologic calculations are available in the Watershed Modeling System (WMS) and in the FHWA Hydraulic Toolbox.

The software has been structured to be self-contained and this help file functions as the program's user's manual. This facilitates its use by roadway design squads. However, the knowledgeable hydraulic engineer will also find the software package useful because it contains advanced features. This help file provides necessary instructions and clarifications.