A Comparison of IRI and Collision Rates in the Province of Alberta

摘要

The mission of every highway agency in Canada and many parts of the world is to provide safe and reliable road network. Safe roads are simply defined as roads with few collisions and a reliable road is a road which is mostly passable and available to road users year round. Many highway agencies such as Alberta Ministry of Transportation usually evaluate road safety by the number of collisions and assess roads reliability using a performance measure called International Roughness Index (IRI). IRI is one of the most commonly and widely used methods of performance measurement. Roughness affects drivers and vehicles performance and it can be expressed by IRI. In this research the relationship between IRI and road safety is estimated to match IRI values with the province of Alberta safety goals. Selected Alberta highways including Trans-Canada highway number two between Calgary and Edmonton, highway number 11 and highway number 16 were considered in this study. IRI values in 50-meters and 1-kilometer intervals and number of collisions in the same intervals and also number of collisions per kilometer divided by AADT were considered for the analysis. Overall highways roughness and number of collisions were compared and correlation coefficients between IRI and number of collisions were calculated. Statistical analysis of data showed that IRI and number of collisions are statistically correlated and that roads with small IRI values will have fewer collisions in comparison to similar roads with higher IRI values.