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Impact of traffic congestion on road accidents: a spatial analysis of the M25 motorway in England

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journal contribution
posted on 2009-09-15, 12:58 authored by Chao Wang, Mohammed Quddus, Stephen Ison
Traffic congestion and road accidents are two external costs of transport and the reduction of their impacts is often one of the primary objectives for transport policy makers. The relationship between traffic congestion and road accidents however is not apparent and less studied. It is speculated that there may be an inverse relationship between traffic congestion and road accidents, and as such this poses a potential dilemma for transport policy makers. This study aims to explore the impact of traffic congestion on the frequency of road accidents using a spatial analysis approach, while controlling for other relevant factors that may affect road accidents. The M25 London orbital motorway, divided into 70 segments, was chosen to conduct this study and relevant data on road accidents, traffic and road characteristics were collected. A robust technique has been developed to map M25 accidents onto its segments. Since existing studies have often used a proxy to measure the level of congestion, this study has employed a precise congestion measurement. A series of Poisson based non-spatial (such as Poisson-lognormal and Poisson-gamma) and spatial (Poisson-lognormal with conditional autoregressive priors) models have been used to account for the effects of both heterogeneity and spatial correlation. The results suggest that traffic congestion has little or no impact on the frequency of road accidents on the M25 motorway. All other relevant factors have provided results consistent with existing studies.

History

School

  • Architecture, Building and Civil Engineering

Published in

Accident Analysis & Prevention

Volume

41

Issue

4

Pages

798 - 808

Citation

WANG, C., QUDDUS, M.A. and ISON, S.G., 2009. Impact of traffic congestion on road accidents: a spatial analysis of the M25 motorway in England. Accident Analysis and Prevention, 41 (4), pp. 798-808

Publisher

© Elsevier

Version

  • AM (Accepted Manuscript)

Acceptance date

2009-04-12

Publication date

2009-05-03

Notes

This was published in the journal, Accident Analysis and Prevention [© Elsevier]. It is also available at: http://dx.doi.org/10.1016/j.aap.2009.04.002

ISSN

0001-4575

Language

  • en

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