Safety performance functions for ramp terminals at diamond interchanges.

Author(s)
Lyon, C. Persaud, B. & Hahn, J.
Year
Abstract

This report documents two efforts to support CDOT in the area of Safety Performance Function (SPF) development. The first involved the data collection and development of SPFs for five categories of ramp terminals at diamond interchanges. For each category, data for the period 2000 to 2006 were collected at sites selected to ensure statewide geographical representation and coverage of the range of traffic volume and other variables in each category. The second effort involved estimating the overdispersion parameters for a number of existing SPFs already in use by CDOT for various roadway segment categories. These parameters are required for implementing the state-of-the-art empirical Bayes procedure for various safety management processes. The development of SPFs for the five categories of ramp terminals was successful. Separate SPFs were developed for total and for injury (fatal+injury) accidents. The calibration of overdispersion parameters for the existing roadway segment SPFs was also successful. Implementation: The developed safety performance functions, as well as the estimated overdispersion parameters, can be used immediately by CDOT for applying state-of-the-art methodologies for road safety management activities. (Author/publisher)

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Publication

Library number
20120022 ST [electronic version only]
Source

Denver, CO, Colorado Department of Transportation, DTD Applied Research and Innovation Branch, 2011, VI + 16 p. + 4 app.; CDOT-2011-9

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