The scope of work for SHRP 2 Reliability Project L08, Incorporating Travel Time Reliability into the Highway Capacity Manual, called for developing methods that could potentially address travel time reliability in the analytic procedures for freeway facilities and urban streets in the Highway Capacity Manual (HCM). This research resulted in two chapters that the TRB Committee on Capacity and Quality of Service has approved for inclusion in the HCM. The first is Chapter 36, concerning freeway facilities and urban streets, and the second is a supplemental Chapter 37, which provides more detail on the methodologies. Corresponding to the methodologies for incorporating reliability into the Highway Capacity Manual for freeway facilities and urban streets are new computational engines developed in conjunction with the 2010 HCM that work with FREEVAL and STREETVAL. After this project was completed, the SHRP 2 Reliability Program conducted four pilots in the states of California, Florida, Minnesota, and Washington, in part to test the new computational software for addressing reliability. Recommendations for improving the software were compiled and selected enhancements were made, generally to make the software more user friendly. While SHRP 2 finished the enhancements, further work on improving the reliability highway capacity analysis products has occurred under National Cooperative Highway Research Program (NCHRP) Project 03-115, Production of a Major Update to the Highway Capacity Manual. Those interested in the treatment of reliability in highway capacity analysis should examine this NCHRP work when it is completed. Interested individuals should also monitor the decisions of the TRB Committee on Highway Capacity and Quality of Service for approved updates to the manual. The Highway Capacity Manual is one of the most widely consulted technical references in the transportation field. The work performed under SHRP 2 Reliability Project L08 is likely to allow decision makers, practitioners, and researchers to better understand the implications of nonrecurring congestion factors, such as incidents, weather, and work zones, for the capacity analysis, assessment of level of service, and performance evaluation of freeway facilities and urban streets. (Author/publisher)
Samenvatting