Incorporation of Travel Time Reliability into the Highway Capacity Manual (SHRP 2 Project L08)
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Greetings!
Travel time reliability aims to quantify variation in travel times. It is defined using the entire range of travel times for a given trip, for a selected time period (for example, the p.m. peak period on weekdays), and over a selected horizon (for example, a year). Incorporation of Travel Time Reliability into the Highway Capacity Manual (HCM) (SHRP 2 Project L08) had two objectives: 1) incorporate nonrecurring congestion impacts into the HCM procedure; and 2) expand the analysis horizon from a single study period to an extended time horizon of several weeks or months to assess the variability and the quality of service the facility provides to its users. This project created two proposed chapters for the Transportation Research Board's Highway Capacity Manual (HCM) that introduce the concept of travel time reliability and offer new analytic methods. The chapters were prepared under SHRP 2 Project L08, but they have not been officially accepted by the Highway Capacity and Quality of Service (HCQS) Committee of the Transportation Research Board. The HCQS Committee has responsibility for approving the content of the HCM. The project final report is available at http://www.trb.org/Main/Blurbs/169594.aspx, and the Proposed Chapters for Incorporating Travel Time Reliability into the Highway Capacity Manual are available at http://www.trb.org/Main/Blurbs/169595.aspx.
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