01550178

Component

https://doi.org/10.3141/2513-01

Road agencies set quantitative targets and adopt related road safety strategies in accordance with each agency’s priorities and available resources. Benefit–cost analyses are carried out to support the decision-making process, and alternative measures are ranked according to their expected benefits and benefit–cost ratios, calculated with a safety performance function (SPF) and crash modification factors (CMFs) as predictors of future safety performance. Because of the variance in CMFs and crash frequency, it is uncertain what the benefits of some future actions will be. The chance of making a wrong decision depends on the standard deviations of the probability distributions of the CMFs and the SPF. To deal with the inherent uncertainty in the decision-making process, a reliability-based assessment of the benefits must be performed to introduce a stochastic approach. In this paper, the variances in the CMFs and SPFs are taken into account in a reliability-based benefit–cost analysis to address the improvements and issues associated with an accurate probabilistic approach when compared with deterministic results or other approximated procedures. A case study is presented that compares safety countermeasures selected to reduce crash frequency and severity on sharp curves on freeways. These measures include delineation systems, shoulder rumble strips, and retrofitted safety barriers, individually and in combination. Monte Carlo simulations were applied to calculate the probability of the failure of the benefit–cost analysis statements. The results and comparisons with alternative approaches, such as the approach proposed in the Highway Safety Manual, are presented and show remarkable differences in the evaluation outcomes.

01589988

15-2226

English

pp 1–10

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369428

Print

Figures (3) ; References (27) ; Tables (7)

Benefit cost analysis; Case studies; Crash rates; Crash severity; Economic impacts; Highway safety; Mathematical models; Retrofitting; Safety engineering; Safety management

Economics; Highways; Safety and Human Factors; I85: Safety Devices used in Transport Infrastructure

TRIS, TRB, ATRI

Dec 30 2014 12:47PM

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