Institute for Transportation

About the research

The objective of the project was to develop procedures to help the Iowa planning community address three common traffic planning issues: bypass analysis, interchange justification, and traffic impact analysis. The main emphasis of this study is on using GIS-based travel demand modeling tools to address planning studies. However, the use of planning models, even if developed with minimal resources, may not be the only or even the best way to approach bypass or interchange planning. Where appropriate, an analyst should consider the most efficient means to arrive at travel forecasts. For example, the interchange justification section describes the use of travel estimates, obtained from a travel model, in capacity analysis software. Naturally, if sufficient travel forecasts can be obtained from manual methods, these can be used directly by the analysis software. It is left to the discretion of the planning analyst to determine the efficacy of using the GIS-based model development procedures described.