Effects of pavement condition on roadway safety in the province of Alberta

ABSTRACT

The mission of every highway agency in many parts of the world is to provide safe, reliable, and economic road network. Many highway agencies such as Alberta Ministry of Transportation usually evaluate road safety by the number of collisions and assess the reliability of roads using a performance index called International Roughness Index (IRI). This research aimed at modeling the relationship between pavement condition and number of collisions in the province of Alberta, Canada. All rural highways in Alberta were considered. Zero inflated Poisson (ZIP) and NB regression were used to estimate the relationship between the number of collisions and the road IRI value and rut depth. Other variables such as average annual daily traffic, alignment, geometry and weather condition were also considered. Based on the outcomes, IRI and number of collisions are correlated; the number of collisions increases with increasing IRI. Results suggest that IRI can be used as an indicator of diminished road safety in Alberta. Highway agencies can consider the effects of network level IRI on road safety as a decision support tool for road maintenance and rehabilitation programs.

KEYWORDS:

• collisions
• International Roughness Index (IRI)
• road safety
• roughness
• rut depth

Acknowledgments

The authors wish to thank the University of Kharazmi Research Group and the University of Calgary for their help and support in performing this project.