Relationship Between Traffic Volume and Accident Frequency at Intersections

Abstract

Driven by the high social costs and emotional trauma that result from traffic accidents around the world, research into understanding the factors that influence accident occurrence is critical. There is a lack of consensus about how the management of congestion may affect traffic accidents. This paper aims to improve our understanding of this relationship by analysing accidents at 120 intersections in Adelaide, Australia. Data comprised of 1629 motor vehicle accidents with traffic volumes from a dataset of more than five million hourly measurements. The effect of rainfall was also examined. Results showed an approximately linear relationship between traffic volume and accident frequency at lower traffic volumes. In the highest traffic volumes, poisson and negative binomial models showed a significant quadratic explanatory term as accident frequency increases at a higher rate. This implies that focusing management efforts on avoiding these conditions would be most effective in reducing accident frequency. The relative risk of rainfall on accident frequency decreases with increasing congestion index. Accident risk is five times greater during rain at low congestion levels, successively decreasing to no elevated risk at the highest congestion level. No significant effect of congestion index on accident severity was detected.

Exploring the Impact of Driver Adherence to Speed Limits and the Interdependence of Roadside Collisions in an Urban Environment: An Agent-Based Modelling Approach

“…This study also shows that increases in collisions are more likely as more vehicles break speed limit rules. This study's results do not reflect the same linear-to-nonlinear relationship between accidents and traffic levels as [71,72]. At low to mid traffic densities, collisions increase disproportionately as traffic density increases.…”

“…This study also suggests that lower traffic density on average leads to fewer collisions regardless of adherence levels, as was observed in [72]. However, as adherence decreases, this leads to increased collisions relative to the number of vehicles in the urban environment.…”

“…Similarly, the authors in [71] found this to be the case on two to three-lane motorways in France. However, this is not true at intersections [72], or on urban roads in London [51,71], where the number of accidents was found to increase linearly at low to mid-levels of traffic and nonlinearly at high levels of traffic.…”

Observations on the Relationship between Crash Frequency and Traffic Flow

“…The hypothesis behind this work was the assumption that at least the crash frequency that involves two cars should be a second-order polynomial function of the traffic flow [30]. A similar idea is also proposed in [27,31].…”

Traffic accidents and delays present contrasting pictures of traffic resilience to coastal flooding in the San Francisco Bay Area

“…The relationship has not been studied as extensively for car accidents in urban and suburban settings. One observational study monitoring 120 signal intersections in Adelaide, Australia found that car accident counts increase with hourly traffic volumes, with an especially sharp increase at very high traffic volumes [19]. For pedestrian accidents, empirical studies have limited temporal resolution, but existing work suggests that annual accident rates correlate with average annual traffic volumes in an approximately linear way [20,9].…”