This research developed methodologies for measuring the effects of congestion on the value that highway users place on travel-time savings and predictability. The methodologies were used to generate values for factors for different degrees of congestion. The research also defined an approach for incorporating these factors into highway user-cost estimates.

The agency final report addresses two important aspects of travel time: First, do travelers and freight carriers place a premium on travel-time savings (or reduced delays) during periods of congestion? Second, is there a value placed on the predictability of travel times?

Hickling Lewis Brod, Inc. (now HLB Decision Economics, Inc.), in Silver Spring, Maryland, was awarded a continuation contract to conduct NCHRP Project 2-18(2), "Validation of Travel-Time Savings and Predictability in Congested Conditions for Highway User-Cost Estimation." The research concentrated on the value of travel time during periods when stop-and-go traffic occurred at E and F levels of service. Under those conditions, congestion not only results in longer travel times, but also makes travel times less predictable, both for passenger travel and for freight shipments. The results of this research provide current values of passenger travel time. Incorporating these research results into standard highway user-cost analysis requires data on segmentation of trips by purpose (work or non-work), household income, and period (peak or off-peak). The report concludes that, although the results of the freight travel survey conducted for this research confirm the importance of transit time and freight cost in shipping decisions, the survey fails to measure a significant value for changes in transit-time predictability. Results from this research are published as NCHRP Report 431, "Valuation of Travel-Time Savings and Predictability in Congested Conditions for Highway User-Cost Estimation."

Status: The agency's revised final report has been received and published.

Product Availability: Published as NCHRP Report 431, "Valuation of Travel-Time Savings and Predictability in Congested Conditions for Highway User-Cost Estimation."