Federal and state governments have played a vital role in the nation economy by facilitating the movement of people and goods through significant investments in highways. At the federal level, the Department of Transportation (DOT) Federal Highway Administration (FHWA) uses a computer model known as the Highway Economic Requirements System (HERS) to estimate the future investment required to maintain and improve the nation highways. DOT reports the results of this analysis to the Congress on a biennial basis. However, state governments make a large number of highway infrastructure investment decisions. States currently use a variety of analytic tools to make these decisions. Interest in using HERS at the state level has grown. Two states Indiana and Oregon are already using customized versions of the model, and in December 2000, FHWA began a pilot project to test its state-level version of HERS, called HERS-ST, with interested states.

GAO-01-299 Highway Infrastructure: FHWA's Model for Estimating Highway Needs Has Been Modified for State-Level Planning

The Highway Economic Requirements System (HERS) is an economic model that uses highway performance monitoring system (HPMS) data to project future highway conditions and requirements. HERS is a highly complex model that, at the national level, uses samples of the highway network taken from the HPMS data. As a result, at the national level it is only used for aggregate network-level analysis (planning-level analysis). When the Federal Highway Administration's Office of Asset Management was established in 1999, the office began developing the state version of HERS, or HERS-ST. HERS-ST has since evolved into a model that is specifically crafted for states. A DOS version of HERS-ST was demonstrated at a workshop attended by representatives of several state transportation agencies in 2001. Since then, several improvements have been made to the software, including updates for a Windows environment and the addition of GIS capabilities. The current project will yield a HERS-ST specifically for Iowa, but one that can be used as a model for other states.