Study Details
Study Title: Development of crash modification factors of horizontal curve design features for single-motorcycle crashes on rural two-lane highways: A matched case-control study
Authors: Xin et al.
Publication Date:FEB, 2019
Abstract: Single-motorcycle crashes are overrepresented on horizontally curved segments of rural, two-lane, undivided (RTU) highways. However, the relationship between single-motorcycle crash risk and the design features of horizontal curves on RTU highways is not well-studied in existing literature. This study aims to quantify the effect of horizontal curve type and radius on the risk of single-motorcycle crashes with a matched case-control study that can address the issues of the low sample mean, aggregation bias, and uncontrolled confounders existing in the traditional cross-sectional study. In the matched case-control study, three matching factors—year, annual average daily traffic (AADT), and segment length—were selected to match controls (RTU segments without crash records) with cases (RTU segments with crash records). A total of 1601 cases and 16,010 matched controls over 11 years (2005–2015) were identified as matched-strata. A conditional logistic model was fitted on the matched-strata data to estimate the crash modification factors (CMFs) of horizontal curve design features for single-motorcycle crashes. The modeling results highlighted the interaction effects between curve type and radius on the risk of single-motorcycle crashes. Sharp (radius = 1500 ft) non-reverse curves were identified as the riskiest curve design for motorcyclists, followed by sharp reverse curves and moderate (1500 ft < radius = 3000 ft) reverse curves. The study also revealed that motorcyclists might take safety-compensation behaviors on sharp curves, narrow shoulders, and poor pavement conditions. Engineering and education countermeasures are suggested for comprehending curve presence and associated risk level, reducing curve entry speed, and improving safety awareness. Finally, the limitations of the study and possible solutions are discussed.
Study Citation: Xin, C., Z. Wang, C. Lee, P.S. Lin, T. Chen, R. Guo, and Q. Lu. "Development of crash modification factors of horizontal curve design features for single-motorcycle crashes on rural two-lane higwhays: A matched case-control study:. Accident Analysis and Prevention, Vol. 123, (2019), pp. 51-59.
Related Citations: Wang, Z., C. Lee, P.S. Lin, R. Guo, C. Xin, R.D.T.N. Kolla, R. Yang, and A. Vasili. "Study on Motorcycle Safety in Negotiation with Horizontal Curves in Florida and Development of Crash Modification Factors." Report No. FDOT BDV25-977-21. Florida Department of Transportation. Tallahassee, Florida. (October 2018).
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Alignment
Countermeasure: Change from horizontal tangent to a flat horizontal curve
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 1.62 | -62 |  | Other | All | Not specified | Rural |
Countermeasure: Change from horizontal tangent to a moderate horizontal curve
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 2 | -100 | | Other | All | Not specified | Rural |
| 2.62 | -162 | | Other | All | Not specified | Rural |
Countermeasure: Change from horizontal tangent to a sharp horizontal curve
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 4.92 | -392 | | Other | All | Not specified | Rural |
| 3.21 | -221 | | Other | All | Not specified | Rural |
Countermeasure: Change from horizontal tangent to a slight horizontal curve
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 1.88 | -88 | | Other | All | Not specified | Rural |
