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. 2023 Sep:32:101669.
doi: 10.1016/j.jth.2023.101669. Epub 2023 Aug 11.

Bicycle infrastructure and the incidence rate of crashes with cars: A case-control study with Strava data in Atlanta

Michael D Garber  1   2   3 , Kari E Watkins  4 , W Dana Flanders  1   5 , Michael R Kramer  1 , R L Felipe Lobelo  6 , Stephen J Mooney  7   8 , David J Ederer  9 , Lauren E McCullough  1
Affiliations

Bicycle infrastructure and the incidence rate of crashes with cars: A case-control study with Strava data in Atlanta

Michael D Garber et al. J Transp Health. 2023 Sep.

Abstract

Introduction: Bicycling has individual and collective health benefits. Safety concerns are a deterrent to bicycling. Incomplete data on bicycling volumes has limited epidemiologic research investigating safety impacts of bicycle infrastructure, such as protected bike lanes.

Methods: In this case-control study, set in Atlanta, Georgia, USA between 2016-10-01 and 2018-08-31, we estimated the incidence rate of police-reported crashes between bicyclists and motor vehicles (n = 124) on several types of infrastructure (off-street paved trails, protected bike lanes, buffered bike lanes, conventional bike lanes, and sharrows) per distance ridden and per intersection entered. To estimate underlying bicycling (the control series), we used a sample of high-resolution bicycling data from Strava, an app, combined with data from 15 on-the-ground bicycle counters to adjust for possible selection bias in the Strava data. We used model-based standardization to estimate effects of treatment on the treated.

Results: After adjustment for selection bias and confounding, estimated ratio effects on segments (excluding intersections) with protected bike lanes (incidence rate ratio [IRR] = 0.5 [95% confidence interval: 0.0, 2.5]) and buffered bike lanes (IRR = 0 [0,0]) were below 1, but were above 1 on conventional bike lanes (IRR = 2.8 [1.2, 6.0]) and near null on sharrows (IRR = 1.1 [0.2, 2.9]). Per intersection entry, estimated ratio effects were above 1 for entries originating from protected bike lanes (incidence proportion ratio [IPR] = 3.0 [0.0, 10.8]), buffered bike lanes (IPR = 16.2 [0.0, 53.1]), and conventional bike lanes (IPR = 3.2 [1.8, 6.0]), and were near 1 and below 1, respectively, for those originating from sharrows (IPR = 0.9 [0.2, 2.1]) and off-street paved trails (IPR = 0.7 [0.0, 2.9]).

Conclusions: Protected bike lanes and buffered bike lanes had estimated protective effects on segments between intersections but estimated harmful effects at intersections. Conventional bike lanes had estimated harmful effects along segments and at intersections.

Keywords: Atlanta; Bicycle infrastructure; Bicycling safety; Case-control studies; Causal inference; Georgia; Strava.

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Conflict of interest statement

Declaration of competing interest We the undersigned declare that this manuscript is original, has not been published before and is not currently being considered for publication elsewhere. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We confirm that each author has disclosed on the form below any conflict of interest, in accordance with Elsevier’s standard guidelines. These are summarized below,a and given in full at: www.elsevier.com/authors/author-rights-and-responsibilities#responsibilities. We understand that the Corresponding Author is the sole contact for the Editorial process. He/she is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs.

Figures

Fig. 1.
Fig. 1.
Bicycle infrastructure present in August 2018 in the 8.85-km radius around the intersection of Ponce de Leon Ave NE and Monroe Dr NE in Atlanta, GA. An interactive version of this map is available here: https://michaeldgarber.github.io/diss/atl-bike-infra-201808.
See this image and copyright information in PMC

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