Economic and Financial Support for ADOT Highway Programs
Like many state departments of transportation, the Arizona Department of Transportation (ADOT) relies on a variety of taxes on goods and services as well as highway user fees to fund the state's highway construction and maintenance program. HDR has provided economic and financial services to ADOT since 1988, developing econometric models and computer programs to forecast revenues flowing into state and regional roadway improvement funds.
We've continually refined our methods to improve accuracy. For example, by applying our consensus-building Risk Analysis Process (RAP), we made it possible for a panel of experts to convene in an open forum to air and reconcile conflicting outlooks. In 2005, we redefined several highway user fund categories to improve the accuracy of the analysis and forecast. New forecasting models were developed in an Microsoft Excel-based risk analysis tool to enable ADOT staff to array the trends, baseline projections and what-if policy analysis in a user-friendly graphical and tabular format. The new format made it easier to communicate results to elected officials and the general public. These changes also improved the accuracy of forecasting models, delivering recent overall margins of error ranging from 0.3 percent to 3.0 percent.