Transportation Asset Management Case Studies
HERS-ST: The Oregon Experience
Since 1991, the Oregon Department of Transportation (ODOT) has used computer models to support its investment decision-making processes. Initially, Oregon relied on the Highway Performance Monitoring System Analytical Process (HPMS AP). The HPMS AP is an investment/performance simulation model designed to predict the investment required to correct current and future highway system deficiencies. This approach relies primarily on engineering considerations and only marginally considers the highway user. While developing its 1999 Oregon Highway Plan, ODOT decided to change their methodology to one that incorporated economics and the impact of investment decisions on highway users.
At about this time, ODOT became aware of the Highway Economic Requirements System (HERS), a new investment/performance model that had just been introduced by the U.S. Department of Transportation (USDOT) for use at the Federal level. The HERS differs from the HPMS AP in that it incorporates economics into its investment selection simulation procedures. Initially, the national version of HERS was not available for State use, but ODOT obtained a copy through a contractor working on the update of its Highway Plan. ODOT worked closely with the contractor in modifying the software to make it useful as a State-level planning tool. The revised program, which came to be known as HERS-OR, was successfully used in producing the 1999 Oregon Highway Plan. ODOT continues to use the HERS model for selected planning and policy analyses, and envisions significant new applications in the future.
ODOT is one of the first States to use the HERS model for planning and policy analysis at the State level. Recently, Oregon has begun to upgrade from HERS-OR to HERS-ST, the State-level HERS model supported by USDOT. HERS-ST has most of the features of HERS-OR, but also has updated formulas and calculations and is considerably more user friendly.