Speed Index

Abstract

Given the increased emphasis on transportation system operations, transportation agencies require effective operations performance measures. The purpose of the present research effort was to develop and explore the utility of a simple system operations performance measure that meets the following criteria: (a) it is measurable given current sensor deployment, (b) it is understandable to a wide range of individuals, (c) it is applicable on different functional classes of roadways, (d) it is scalable from the lane level up to a regional or statewide measure, and (e) it is independent of major assumptions or estimation techniques. The measure proposed and explored in this paper, the speed index, can be defined as the volume-weighted percentage of the speed limit at which a roadway location, zone, corridor, or even a region operated for a given time period. This measure was demonstrated to be effective in supporting numerous operations analysis activities, including an analysis of seasonal variations in traffic and an in-depth analysis of a single incident's impact on regional conditions. On the basis of the case study presented, it is concluded that the speed index is a viable measure that can be used to support state operations programs.

Get full access to this article

View all access options for this article.

References

Texas Transportation Institute. Table 5. Trends—Travel Time Index, 1982–2002. In 2004 Urban Mobility Study. Texas Transportation Institute, Texas A&M University. mobility.tamu.edu/ums/congestion_data/tables/national/table_5.pdf. Accessed April 2005.

Garber

N. J.

and Hoel

L. A.

Traffic & Highway Engineering, 3rd ed. Brooks/Cole, Pacific Grove, Calif., 2002, pp. 332–333.

Highway Capacity Manual. TRB, National Research Council, Washington, D.C., 2000.

Shaw

NCHRP Synthesis of Highway Practice 311: Performance Measures of Operational Effectiveness for Highway Segments and Systems. Transportation Research Board of the National Academies, Washington, D.C., 2003.

Transgressions (Percentages) of Speed Limit on Motorways. Institute for Road Safety Research, Amsterdam, Netherlands. www.swov.nl/en/kennisbank/index.htm?/en/kennisbank/z_data/inhoud/graph_transgressions_percentage.htm. Accessed March 18, 2005.

Congestion Management Monitoring: Report Summary 2003. Southwest Washington Regional Transportation Council. www.rtc.wa.gov/data/cms/summary03.htm. Accessed March 2005.