Identification and Evaluation of the Cost-Effectiveness of Highway Design Features to Reduce Nonrecurrent Congestion

TRB’s second Strategic Highway Research Program (SHRP 2) S2-L07-RR-1: Identification and Evaluation of the Cost-Effectiveness of Highway Design Features to Reduce Nonrecurrent Congestion focuses on geometric design treatments that can be used to reduce delays due to nonrecurrent congestion.

The report provides a method for incorporating the economic savings due to delay reduction and economic savings due to reliability improvement for a design treatment during a highway life cycle. The report is accompanied by a Design Guide for Addressing Nonrecurrent Congestion.

SHRP 2 Reliability Project L07 also produced an Analysis Tool for Design Treatments to Address Nonrecurrent Congestion: Annotated Graphical User’s Guide Version 2. The guide is intended to assist users of the Microsoft-based Excel tool designed to analyze the effects of highway geometric design treatments on nonrecurrent congestion using a reliability framework. 

The tool is designed to analyze a generally homogeneous segment of a freeway (typically between successive interchanges). The tool allows the user to input data regarding site geometry, traffic demand, incident history, weather, special events, and work zones. Based on these data, the tool calculates base reliability conditions. The user can then analyze the effectiveness of a variety of treatments by providing fairly simple input data regarding the treatment effects and cost parameters. As outputs, the tool predicts cumulative travel time index curves for each hour of the day, from which other reliability variables are computed and displayed. The tool also calculates cost-effectiveness by assigning monetary values.

Subsequent to the analysis tool's release, SHRP 2 Reliability Project L07 produced an Microsoft-based Excel demand generator as a supplement to the analysis tool.

Analysis and Demand Generator Tools Disclaimer – The analysis tool is offered as is, without warranty or promise of support of any kind either expressed or implied. Under no circumstance will the National Academy of Sciences or the Transportation Research Board (collectively "TRB") be liable for any loss or damage caused by the installation or operation of this product. TRB makes no representation or warranty of any kind, expressed or implied, in fact or in law, including without limitation, the warranty of merchantability or the warranty of fitness for a particular purpose, and shall not in any case be liable for any consequential or special damages.