Study Details

Study Title: Evaluation of the Safety Effectiveness of Installing Roadside Barriers with Different Driver, Vehicle, Weather, and Time of Day Conditions

Authors: Park et. al.

Publication Date:JAN, 2016

Abstract: Generally, a crash modification factor (CMF) represents the overall safety performance of a specific treatment. Although many researchers have estimated the safety effects (i.e. 1 - CMF or crash reduction factor (CRF)) of specific treatments (or countermeasures) in reducing crashes, there is a lack of prior studies that explored the variation of CMFs. Thus, the main objectives of this study are 1) to estimate CMFs for the installation of different types of roadside barriers, and 2) to determine the changes of safety effects for different crash types and severities based on different vehicle, driver, weather and time of day information. Two observational before-after analyses (i.e. empirical Bayes (EB) and Full Bayes (FB) approaches) were utilized in this study to estimate CMFs. To consider the variation of safety effects based on different vehicle, driver, weather, and time of day information, the crashes were categorized based on vehicle size (passenger and heavy), driver age (young, middle, and old), weather condition (normal and rain), and time difference (day time and night time). The results show that the addition of roadside barriers is safety effective in reducing severe crashes for all types and run-off roadway (ROR) crashes. On the other hand, it was found that roadside barriers tend to increase all types of crashes for all severities. The results indicate that the treatment might increase the total number of crashes but it might be helpful in reducing injury and severe crashes. In this study, the variation of CMFs was determined for ROR crashes based on the different vehicle, driver, weather, and time information. The results show that guardrails is more safety effective in reducing injury and severe ROR crashes for middle and old age drivers than young age drivers. It was found that the CMFs for injury and severe ROR crashes were lower for heavy vehicles than passenger cars. It was also found that the safety effects of the treatment were higher for injury and severe ROR crashes in night time than day time. Lastly, the CMFs were lower for severe ROR crashes in rain condition than normal weather condition. Based on the findings from this study, it can be recommended to identify the safety effects of specific treatments for different crash types and severity levels with consideration of the different vehicle, driver, weather, and time of day. Also, the results show that there are no big difference between the estimated CMFs from the EB and FB methods.

Study Citation: Park, J., M. Abdel-Aty, and J. Lee. "Evaluation of the Safety Effectiveness of Installing Roadside Barriers with Different Driver, Vehicle, Weather, and Time of Day Conditions". Presented at the 95th Annual Meeting of the Transportation Research Board, Paper No. 16-0678, Washington, D.C., (2016).

Related Citations: Park, J., M. Abdel-Aty, and J. Lee. "Use of empirical and full Bayes before-after approaches to estimate the safety effects of roadside barriers with different crash conditions". Journal of Safety Research, Vol. 58, (2016) pp. 31-40.


CMFs Associated With This Study

Category: Roadside

Countermeasure: Install w-beam guardrail

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
1.12-124 StarsRun off road,Wet roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9644 StarsRun off road,Wet roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.75254 StarsRun off road,Wet roadK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
1.05-54 StarsDay time,Run off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.01-14 StarsDay time,Run off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.89114 StarsDay time,Run off roadK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9824 StarsNighttime,Run off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.73274 StarsNighttime,Run off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.53474 StarsNighttime,Run off roadK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
1.06-64 StarsAllAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9914 StarsAllK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.84164 StarsAllK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
1.01-14 StarsRun off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.89114 StarsRun off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.74264 StarsRun off roadK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
1.15-154 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9824 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.81194 StarsRun off road,OtherK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9374 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.75254 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.65354 StarsRun off road,OtherK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
1.12-124 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.11-114 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9554 StarsRun off road,OtherK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
1.05-54 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.85154 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.7304 StarsRun off road,OtherK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9374 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.8204 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.58424 StarsRun off road,OtherK,APrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9554 StarsDry weather,Run off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.87134 StarsDry weather,Run off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.79214 StarsDry weather,Run off roadK,APrincipal Arterial Other Freeways and ExpresswaysNot specified

Countermeasure: Install w-beam guardrail or concrete barrier

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.84164 StarsDay time,Run off roadK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9284 StarsNighttime,Run off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.71294 StarsNighttime,Run off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.6404 StarsNighttime,Run off roadK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.01-14 StarsAllAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9464 StarsAllK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.82184 StarsAllK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9374 StarsRun off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.84164 StarsRun off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.73274 StarsRun off roadK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.03-34 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9284 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.81194 StarsRun off road,OtherK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9104 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.72284 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.66344 StarsRun off road,OtherK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.06-64 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
1.06-64 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9194 StarsRun off road,OtherK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9374 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.79214 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.69314 StarsRun off road,OtherK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9194 StarsRun off road,OtherAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.8204 StarsRun off road,OtherK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.62384 StarsRun off road,OtherK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9284 StarsDry weather,Run off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.82184 StarsDry weather,Run off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.76244 StarsDry weather,Run off roadK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9284 StarsRun off road,Wet roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9104 StarsRun off road,Wet roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.75254 StarsRun off road,Wet roadK,A,BPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9644 StarsDay time,Run off roadAllPrincipal Arterial Other Freeways and ExpresswaysNot specified
0.9464 StarsDay time,Run off roadK,A,B,CPrincipal Arterial Other Freeways and ExpresswaysNot specified