Study Details
Study Title: Safety Effectiveness of Super 2 Highways in Texas
Authors: Park et al.
Publication Date:JAN, 2012
Abstract: The objective of this study is to evaluate the safety effectiveness of Super 2 highways in Texas. This study utilized the before-after study with the empirical Bayes (EB) method since it is superior to other methods in that it can address the regression-to-the-mean bias. Based on the identified potential study sites in seven Districts (Paris, Childress, Corpus Christi, Austin, Wichita Falls, Yoakum, and Bryan) in Texas, four reference groups were considered by imposing different restrictions. Then, negative binomial regression models were used to develop safety performance functions for each reference group. From the model selection process, the most restricted reference group was selected for the final analysis. For roadway inventory and crash history data, twelve years (1997-2001 and 2003-2009) of Texas data were examined. The analysis used fatal (K), incapacitating injury (A), non-incapacitating injury (B), and minor injury (C) crashes (i.e., property damage only crashes were not included). The EB analyses were carried out for five corridors of about 53 centerline-miles. The results showed that the installation of Super 2 highways led to a statistically significant crash reduction of 35 percent for segment-only crashes (KABC) and 42 percent for segment-and-intersection crashes (KABC) on the study corridors. This finding is consistent with findings of previous safety-related studies of Super 2 corridors, which show improvements in safety with installation of passing lanes, even at traffic volumes higher than those considered under previous guidance in Texas.
Study Citation: Park, B., Fitzpatrick, K., and Brewer, M., "Safety Effectiveness of Super 2 Highways in Texas." Transportation Research Record: Journal of the Transportation Research Board, No. 2280, Transportation Research Board of the National Academies, Washington, D.C., 2012, pp. 38-50. DOI: 10.3141/2280-05
CMFs Associated With This Study
Category: Roadway
Countermeasure: Install periodic passing lanes on rural two-lane highways
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 0.65 | 35 |  | Non-intersection | K,A,B,C | Principal Arterial Other | Rural |
| 0.58 | 42 | | All | K,A,B,C | Principal Arterial Other | Rural |
