Are multiple speed cameras more effective than a single one? Causal analysis of the safety impacts of multiple speed cameras
File(s)
Accepted version
Author(s)
Li, Haojie
Zhu, Manman
Graham, Daniel J
Zhang, Yingheng
Type
Journal Article
Abstract
Most previous studies investigate the safety effects of a single speed camera, ignoring the potential impacts from adjacent speed cameras. The mutual influence between two or even more adjacent speed cameras is a relevant attribute worth taking into account when evaluating the safety impacts of speed cameras. This paper investigates the safety effects of two or more speed cameras observed within a specific radius which are defined as multiple speed cameras. A total of 464 speed cameras at treated sites and 3119 control sites are observed and related to road traffic accident data from 1999 to 2007. The effects of multiple speed cameras are evaluated using pairwise comparisons between treatment units with different doses based on the propensity score methods. The spatial effect of multiple speed cameras is investigated by testing various radii. There are two major findings in this study. First, sites with multiple speed cameras perform better in reducing the absolute number of road accidents than those with a single camera. Second, speed camera sites are found to be most effective with a radius of 200 m. For a radius of 200 m and 300 m, the reduction in the personal injury collisions by multiple speed cameras are 21.4 % and 13.2 % more than a single camera. Our results also suggest that multiple speed cameras are effective within a small radius (200 m and 300 m).
Date Issued
2020-05
Date Acceptance
2020-02-24
Citation
Accident Analysis and Prevention, 2020, 139
ISSN
0001-4575
Publisher
Elsevier
Journal / Book Title
Accident Analysis and Prevention
Volume
139
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/32126326
PII: S0001-4575(19)31605-7
Subjects
Doubly robust estimation
Multiple speed cameras
Propensity score
Road safety
Publication Status
Published
Coverage Spatial
England
Article Number
ARTN 105488
Date Publish Online
2020-02-29