The impact of pedestrian countdown signals on pedestrian-motor vehicle collisions: a reanalysis of data from a quasi-experimental study.
OBJECTIVE
To perform a more sophisticated analysis of previously published data that advances the understanding of the efficacy of pedestrian countdown signal (PCS) installation on pedestrian-motor vehicle collisions (PMVCs), in the city of Toronto, Canada.


METHODS
This is an updated analysis of the same dataset from Camden et al. A quasi-experimental design was used to evaluate the effect of PCS on PMVC. A Poisson regression analysis, using a one-group comparison of PMVC, pre-PCS installation to post-PCS installation was used, controlling for season and temporal effects. The outcome was the frequency of reported PMVC (January 2000-December 2009). Similar models were used to analyse specific types of collisions defined by age of pedestrian, injury severity, and pedestrian and vehicle action. Incidence rate ratios with 95% CI are presented.


RESULTS
This analysis included 9262 PMVC, 2760 during or after PCS installation, at 1965 intersections. There was a 26% increase in the rate of collisions, pre to post-PCS installation (incidence rate ratio=1.26, 95% CI 1.11 to 1.42).


CONCLUSIONS
The installation of PCS at 1965 signalised intersections in the city of Toronto resulted in an increase in PMVC rates post-PCS installation. PCSs may have an unintended consequence of increasing pedestrian-motor vehicle collisions in some settings.
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.
Sarah A
SA
Richmond
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Andrew R
AR
Willan
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.
Linda
L
Rothman
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada.
Andi
A
Camden
Department of Geography and Programs in Environment, University of Toronto Mississauga, Mississauga, Ontario, Canada.
Ron
R
Buliung
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada Department of Pediatrics, University of Toronto, Toronto, Ontario, Canada.
Colin
C
Macarthur
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada Division of Orthopaedic Surgery, Hospital for Sick Children, Toronto, Ontario, Canada Department of Surgery, University of Toronto, Toronto, Ontario, Canada Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada.
Andrew
A
Howard
D000056:Accident Prevention; D000063:Accidents, Traffic / Q000517:prevention & control* / Q000706:statistics & numerical data; D017677:Age Distribution; D002170:Canada; D002958:City Planning; D004779:Environment Design; D006801:Humans; D015994:Incidence; D018986:Motor Vehicles / Q000706:statistics & numerical data*; D011634:Public Health; D012044:Regression Analysis; D012307:Risk Factors; D014505:Urban Population; D016138:Walking / Q000293:injuries*