Contraflows and cycling safety: Evidence from 22 years of data involving 508 one-way streets
Type: Journal Article Venue: Accident Analysis & Prevention Year: 2023
Abstract
Contraflow cycling on one-way streets is a low cost intervention that research shows can improve the cycling experience and increase participation. Evidence from several studies suggest that cyclists on contraflows have a lower crash risk. However, implementing contraflow cycling is often controversial, including in the United Kingdom (UK). In this paper we examine whether contraflow cycling on one-way streets alters crash or casualty rates for pedal cyclists. Focusing on inner London boroughs between 1998 and 2019, we identified 508 road segments where contraflow cycling was introduced on one-way streets. We identified road traffic crashes occurring within 10 m of these segments and labelled them as pre-contraflow, contraflow or contraflow removed crashes. We calculated rates using the number of crashes or casualties divided by the time exposed and generated 95 % confidence intervals using bootstrap resampling. We adjusted the rates for changes in cordon cycling volume and injury severity reporting. There were 1498 crashes involving pedal cyclists: 788 pre-contraflow, 703 contraflow and 7 following contraflow removal. There was no change in adjusted overall pedal cyclist crash or casualty rates when contraflow cycling was introduced. Proximity to a junction doubled the crash rate. The crash rate when pedal cyclists were travelling contraflow was the same as those travelling with flow. We have found no evidence that introducing contraflow cycling increases the crash or casualty rate for pedal cyclists. It is possible that such rates may indeed fall when contraflow cycling is introduced if more accurate spatio-temporal cycling volume data was available. We recommend all one-way streets are evaluated for contraflow cycling but encourage judicious junction design and recommend UK legislative change for mandatory-two-way cycling on one-way streets unless exceptional circumstances exist.
Citation
Caroline Tait, Roger Beecham, Robin Lovelace, and Stuart Barber (2023). Contraflows and cycling safety: Evidence from 22 years of data involving 508 one-way streets. Accident Analysis & Prevention. https://doi.org/10.1016/j.aap.2022.106895
BibTeX
@article{tait_contraflows_2023,
title = {Contraflows and cycling safety: {Evidence} from 22 years of data involving 508 one-way streets},
volume = {179},
copyright = {CC0 1.0 Universal Public Domain Dedication},
issn = {0001-4575},
shorttitle = {Contraflows and cycling safety},
url = {https://doi.org/10.1016/j.aap.2022.106895},
doi = {10.1016/j.aap.2022.106895},
abstract = {Contraflow cycling on one-way streets is a low cost intervention that research shows can improve the cycling experience and increase participation. Evidence from several studies suggest that cyclists on contraflows have a lower crash risk. However, implementing contraflow cycling is often controversial, including in the United Kingdom (UK). In this paper we examine whether contraflow cycling on one-way streets alters crash or casualty rates for pedal cyclists. Focusing on inner London boroughs between 1998 and 2019, we identified 508 road segments where contraflow cycling was introduced on one-way streets. We identified road traffic crashes occurring within 10 m of these segments and labelled them as pre-contraflow, contraflow or contraflow removed crashes. We calculated rates using the number of crashes or casualties divided by the time exposed and generated 95 \% confidence intervals using bootstrap resampling. We adjusted the rates for changes in cordon cycling volume and injury severity reporting. There were 1498 crashes involving pedal cyclists: 788 pre-contraflow, 703 contraflow and 7 following contraflow removal. There was no change in adjusted overall pedal cyclist crash or casualty rates when contraflow cycling was introduced. Proximity to a junction doubled the crash rate. The crash rate when pedal cyclists were travelling contraflow was the same as those travelling with flow. We have found no evidence that introducing contraflow cycling increases the crash or casualty rate for pedal cyclists. It is possible that such rates may indeed fall when contraflow cycling is introduced if more accurate spatio-temporal cycling volume data was available. We recommend all one-way streets are evaluated for contraflow cycling but encourage judicious junction design and recommend UK legislative change for mandatory-two-way cycling on one-way streets unless exceptional circumstances exist.},
language = {en},
urldate = {2022-11-15},
journal = {Accident Analysis \& Prevention},
author = {Tait, Caroline and Beecham, Roger and Lovelace, Robin and Barber, Stuart},
month = jan,
year = {2023},
keywords = {Contraflow, Crash, Cycling, Infrastructure, One-way streets},
pages = {106895},
}Notes
Impact Statement
REF2029 Impact Statement
This paper provides the most comprehensive longitudinal evidence base to date on the safety of contraflow cycling. By analyzing 22 years of crash data (1998–2019) across 508 one-way streets in London, the research definitively refutes the common UK political and public objection that contraflows increase risk. The study’s rigour is evidenced by its use of bootstrap resampling and adjustments for cordon cycling volume and injury severity reporting changes. Key findings—that crash rates are identical regardless of direction and that junctions, not contraflows, are the primary risk factor—have direct implications for UK road legislation. It explicitly calls for a mandatory two-way cycling default for one-way streets, aligning with international best practices and the UK’s “Gear Change” strategy.
Unit of Assessment: UoA 9 (Architecture, Built Environment and Planning).
Alternative UoA: UoA 17 (Geography and Environmental Studies).
PGR student co-author: True (Caroline Tait).
Potential for Double Weighting: No.
Author rating: Likely 4* due to the longitudinal scale and policy influence.
Author Contribution:
Tait (PGR) conducted the primary data collection from thousands of Traffic Regulation Orders (TROs) in The Gazette, designed the spatial join methodology, and performed the statistical analysis. Lovelace and Beecham provided supervision on spatial data science and transport modeling. Barber provided expertise in statistical resampling and uncertainty estimation.