Prior to the implementation of HERS-IN, the agency used a spreadsheet-type approach to identify system deficiencies. The data sheet included average annual daily traffic (AADT) data from a three-year count cycle and other road inventory characteristics, in combination with a simplified 24-hour capacity estimate, to produce volume-to-capacity maps. Traffic forecasts were based upon historical trends by functional classification. The planning process was based on a timeframe of about six to seven years and was documented in the Highway Improvement Program.
When INDOT established its long-range planning section in the 1980s, the agency began investigating highway needs analysis options. One approach of particular interest was the Idaho Transportation Department's Highway Needs Analysis Reports, which incorporated the tabular output of the FHWA/Wilbur Smith Needs Model (HWYNEEDS) with a system of highway system maps using a cut-and-paste approach. This method provided both a systems-level analysis and the identification of project-specific highway improvements.
"We saw what Idaho had done," says Steve Smith, manager for the Long Range Planning Section of the Office of Urban and Corridor Planning. "It looked like an interesting way to approach needs analysis." Based on that, INDOT chose to implement a systems analysis program utilizing the Highway Performance Monitoring System (HPMS).
The drawback with HPMS was that it only used sample data and the results weren't always applicable to the State's jurisdictional roadways. "We were able to come up with a functional classification but couldn't separate the State jurisdictional system," says Smith. INDOT's planning division was looking for a needs analysis model that would identify specific deficiency locations and evaluate alternative highway investment levels, and it appeared that a customized version of the HERS national software might be the answer.
Customizing the software would require some major changes, as the national model was based on a sampling system that estimated the number of miles of highway improvements needed but not the locations. Indiana wanted to be able to do both. The ability to analyze potential capacity expansion projects was also high on INDOT's wish list.