Study Details
Study Title: Crash Reduction Analysis of Friction Improvement Surface Treatments in Georgia
Authors: Liu et al.
Publication Date:JAN, 2023
Abstract: Crashes on curves represent 25 % of all roadway fatalities the vast majority of these fatalities are roadway departures. An effective treatment to mitigate roadway departures are friction improvement surface treatments (FISTs). The Georgia Department of Transportation (GDOT) has implemented friction improvements on more than 400 curves. Before this study, there were no crash modification factors (CMFs) for these friction improvements in Georgia. Additionally, a comparison of the effectiveness of different materials in Georgia was not conducted. Thus, the objective of this study was to analyze the crash reduction effectiveness of three FISTs in Georgia. These materials include phonolite, lightweight aggregate (LWA), and high friction surface treatment (HFST, or calcined bauxite). This objective was achieved by using naïve Bayes and empirical Bayes methods to develop CMFs. The calculated CMFs show that HFST significantly reduces curve crashes with an overall CMF of 0.672. HFST is the only material implemented where the calculated CMFs provided significant evidence for crash reduction. Crash types that were significantly reduced include single vehicle, those labeled as negotiating a curve, and wet road. The CMF was then modeled as a function of the roadway environment. It was found that significant curve site characteristics that led to more reduction in crashes were 1) prior crash frequency, 2) absence of an intersection, and 3) lower traffic volumes. These findings are used to display CMFs for different site characteristics and can be used to strategize implementation of HFST on curves in the future.
Study Citation: Liu, M., J. Li, R. Knezevich, T. Tsai. "Crash Reduction Analysis of Friction Improvement Surface Treatments in Georgia". Presented at the 102nd Annual Meeting of the Transportation Research Board, Paper No. 23-02971, Washington, D.C., (2023).
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Roadway
Countermeasure: Improve pavement friction (HFS-High Friction Surfacing)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|
| 0.672 | 32.8 |  | All | All | All | Not specified |
Countermeasure: Improve pavement friction at horizontal curves (Light Weight Aggregate)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|
| 1.267 | -26.7 |  | All | | All | Not specified |
| 4 | -300 | | Other | | All | Not specified |
Countermeasure: Improve pavement friction at horizontal curves (Phonolite/Wyoming Bauxite)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|
| 0.916 | 8.4 | | All | | All | Not specified |
