01474117

Component

https://doi.org/10.3141/2358-04

http://scholar.google.com...rter&publication_year=2013

Safety (in terms of expected crash frequency and severity) was compared on road segments where design exceptions had been approved and constructed and on similar road segments where no design exceptions had been approved or constructed. Data were collected for design exceptions in Utah from 2001 to 2006. Multiple data sources were used to identify and define road segments with and without design exceptions. Propensity scores were applied to assess similarities between treatment and comparison sites. Ultimately, 34 total nonfreeway segments with design exceptions and 80 nonfreeway segments without design exceptions were used for modeling. The relationship between the presence of design exceptions and crash frequency was explored with a negative binomial regression modeling approach. The relationship between the presence of design exceptions and crash severity was explored in three ways: (a) computation of severity distributions at locations with and without design exceptions, (b) estimation of separate negative binomial regression models by severity level, and (c) estimation of multinomial logit models to predict the severity outcome of a crash. The presence of design exceptions was represented in the regression models by an indicator variable (where 1 = one design exception or more and 0 = no design exceptions). Crash data from 2007 through 2010 were used for model estimation. No significant differences were observed in expected crash frequencies and crash severities between nonfreeway road segments with and without design exceptions. This overall finding was consistent with two previous related efforts in Kentucky and Indiana.

01498551

13-4078

English

pp 29–37

2013

Transportation Research Record: Journal of the Transportation Research Board

9780309286749

Print

Figures (1) ; References (21) ; Tables (5)

Crash rates; Crash severity; Design standards; Highway design; Highway safety

Utah

Design; Highways; I22: Design of Pavements, Railways and Guideways

PRP, TRIS, TRB, ATRI

Feb 5 2013 12:47PM

• Algorithm for Analyzing Horizontal Sight Distance from Lane Centerline Coordinates
• Context-Sensitive Approach for Network Selection of Infrastructure Projects
• Daytime and Nighttime Passing Maneuvers on a Two-Lane Rural Road in Spain
• Decision Tool to Define and Quantify Interchange Complexity
• Evaluating Traveler Preferences, Values, and Behaviors Associated with Public Rest Areas
• Evaluation of Wheat Straw Wattles for Velocity Reduction in Ditch Check Installations
• Green Infrastructure Design for Pavement Systems Subject to Rainfall–Runoff Loadings
• Roadside Clearance Limit on Horizontal Curves with Transition Arcs: Sites with Circular Arcs Shorter Than Sight Distance