01550185

Component

https://doi.org/10.3141/2515-08

The focus of this paper is on presenting a revised method to develop calibration factors (CFs) with consideration of the change in the crash recording threshold (CRT), which is a minimum value to report crashes. The higher the CRT, the fewer the number of recorded property damage only (PDO) crashes. In this paper, a threshold adjustment factor was defined and used to estimate the new CFs. Because the threshold change affects only the total number of crashes and the PDO crashes, the percentage of fatal and injury (F/I) crashes before the threshold change needs to be adjusted to properly estimate the total number of F/I crashes. The revised method was verified with case studies using Illinois data. Five years of crash data were gathered and used to develop CFs for five roadway types, including two-lane undivided (2U), two-lane with a two-way left-turn lane (3T), four-lane undivided (4U), four-lane divided (4D), and four-lane with a two-way left-turn lane (5T). Because of an increase in the CRT in 2009, a method is needed to supplement the standard approach to adjust CFs with consideration of the effect of the new CRT. The CFs for 2U and 3T before–after considering the threshold adjustment factor were 1.44/1.32 and 1.24/1.12, respectively, while the CFs before–after the threshold change for 4U, 4D, and 5T were 0.99/0.85, 0.68/0.55, and 0.77/0.69, respectively. The results proved that the revised method can help state and local agencies predict the number of crashes without redeveloping new CFs resulting from the change in CRT.

01587392

15-2298

English

pp 57–62

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369305

Print

References (12) ; Tables (6)

Calibration; Crash characteristics; Crash risk forecasting; Data collection; Four lane highways; Suburbs; Two lane highways; Urban areas

Illinois

Data and Information Technology; Highways; Safety and Human Factors; I81: Accident Statistics

PRP, TRIS, TRB, ATRI

Dec 30 2014 12:48PM

• Classification of Gaps at Uncontrolled Intersections and Midblock Crossings Using Support Vector Machines
• Empirical Bayes Before–After Study on Safety Effect of Narrow Pavement Widening Projects in Texas
• Evaluation of the Safety Effectiveness of the Conversion of Two-Lane Roadways to Four-Lane Divided Roadways: Bayesian Versus Empirical Bayes
• Exploring Piecewise Linear Effects of Crash Contributing Factors with a Novel Poisson–Mixed Multivariate Adaptive Regression Splines Model
• Is Horizontal Curvature a Significant Factor of Safety in Rural Multilane Highways?
• Modeling Crash Rates for a Mountainous Highway by Using Refined-Scale Panel Data
• Multivariate Full Bayesian Hot Spot Identification and Ranking: New Technique
• Results and Lessons from Local Calibration Process of the Highway Safety Manual for the State of Maryland
• Safety Analysis of Freeway Segments with Random Parameters
• Safety Impacts of a Statewide Centerline Rumble Strip Installation Program
• Statistical Evaluation of Different Sample Sizes for Local Calibration Process in the Highway Safety Manual
• Strength of the Variable: Calculating and Evaluating Safety Performance Function Calibration Factors for the State of Ohio
• Transferability and Calibration of Highway Safety Manual Performance Functions and Development of New Models for Urban Four-Lane Divided Roads in Riyadh, Saudi Arabia
• Validation Technique Applied to Oregon Safety Performance Function Arterial Segment Models