Study Details
Study Title: Safety Performance Functions for Low-Volume Roads
Authors: Acqua and Russo
Publication Date:NOV, 2010
Abstract: This paper analyzes roadway safety conditions using the network approach for a number of Italian roadways within the Province of Salerno. These roadways are characterized by low-volume conditions with a traffic flow of under 1,000 vehicles per day and they are situated partly on flat/rolling terrain covering 231.98 kilometers and partly on mountainous terrain for 751.60 kilometers. Since 2003, the Department of Transportation Engineering at the University of Naples has been conducting a large-scale research program based on crash data collected in Southern Italy. The research-study presented here has been used to calibrate crash prediction models (CPMs) per kilometer per year. The coefficients of the CPMs are estimated using a non-linear multi-variable regression analysis utilizing the least-square method. In conclusion, two injurious crash prediction models were performed for two-lane rural roads located on flat/rolling area with a vertical grade of less than 6 percent and on mountainous terrain with a vertical grade of more than 6 percent. A residuals analysis was subsequently developed to assess the adjusted coefficient of determination and p-value for each assessible coefficient of the prediction model. CPMs are a useful tool for estimating the expected number of crashes occurring within the roads' geometric components (intersections and road sections) as a function of infrastructural, environmental, and roadway features. Several procedures exist in the scientific literature to predict the number of crashes per kilometer per year. CPMs can also be used as a tool for safety improvement project prioritization.
Study Citation: Acqua, G. D. and F. Russo., "Safety Performance Functions for Low-Volume Roads." Presented at the 90th Annual Meeting of the Transportation Research Board, Washington, D.C., (2011).
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Alignment
Countermeasure: Change horizontal alignment
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
 | |  | All | K,A,B,C | Not Specified | Rural |
Countermeasure: Change vertical grade
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| | | All | K,A,B,C | Not Specified | Rural |
| | | All | K,A,B,C | Not Specified | Rural |
Category:Roadway
Countermeasure: Increase roadway width (lanes and shoulders in meters)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| | | All | K,A,B,C | Not Specified | Rural |
| | | All | K,A,B,C | Not Specified | Rural |
Category:Speed management
Countermeasure: Change mean speed (km/hr)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| | | All | K,A,B,C | Not Specified | Rural |
| | | All | K,A,B,C | Not Specified | Rural |
