00771210

Component

https://doi.org/10.3141/1665-06

http://scholar.google.com...wart&publication_year=1999

As congestion on two-lane rural roads increases, there is increasing interest in conversion to a four-lane undivided or four-lane divided facility within the same corridor. There is a surprising lack of research aimed at precisely estimating the safety benefits of these conversions. This lack is due in large part to the difficulty of conducting such research, because the best answer would result from analysis of a large sample of converted locations covering many different before-and-after configurations. The authors have attempted to estimate the benefits of such conversions by developing cross-sectional models producing crash rates for typical sections of two- and four-lane roadways in four different states. Predicted crash reductions for conversion from most typical two- to four-lane divided sections ranged from 40 to 60%. The reduction due to conversion to a four-lane undivided configuration is much less well defined, ranging from no effect to perhaps a 20% reduction. Continuing research needs include (a) verification of the undivided four-lane results, (b) additional information on the effects of driveways, (c) estimates for higher levels of two-lane average daily traffic, (d) expansion of the outcome variable to include crash severity, and (e) verification of all results by before-and-after studies of actual conversions.

This paper appears in Transportation Research Record No. 1665, Statistical Methods in Transportation and Safety Data Analysis for Highway Geometry, Design, and Operations.

English

p. 35-43

1999

Transportation Research Record

0309070651

Figures (4) ; References (4) ; Tables (3)

Benefits; Crash rates; Cross sectional studies; Divided highways; Estimating; Four lane highways; Research; Rural highways; Safety; Two lane highways

Design; Highways; Safety and Human Factors; I82: Accidents and Transport Infrastructure

TRIS, TRB, ATRI

Oct 21 1999 12:00AM

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