This report sets out requirements for travel time reliability within a performance-based planning process. The authors present two succinct tables that describe requirements for person and freight trips for reliable transport. A discussion of goals, performance measures, and performance targets follows. Performance measures are presented that pertain to roadway users and agencies. The report examines the cost-effectiveness of different ways to improve travel time reliability. The analysis draws from a wide range of literature, but because few data on outcomes of different strategies to improve travel time reliability are available, assessment of cost-effectiveness is qualitative. Nonetheless, in perusing the tables of information, one can form reasonable conclusions about what large, medium, and small expenditures for different types of operations and capacity improvement projects can produce in terms of a small, modest, or large effect on travel time reliability. The research included an effort to determine the economic value of improvements in travel time reliability by applying options theory from the financial sector. This method is predicated on determining the certainty equivalent of the variability of speed. This innovative approach, briefly summarized in the body of the report and described in an appendix, deserves further exploration despite the lack of consensus from experts about its validity. A prominent part of the report presents a forecast of the year 2030 under alternative assumptions that may influence travel time reliability. The researchers set out three alternative outcomes–optimistic, mediocre, and pessimistic–regarding climate change, economics, and demographics. In addition, they examined a range of technological developments that might affect reliability. To paint a picture of the future, they prepared a concept of operations for the year 2030. Among the various ways to improve travel time reliability, pricing is strongly emphasized by the researchers. (Author/publisher)
Abstract