Safe streets for cyclists? Quantifying the causal impact of cycling infrastructure interventions on safety

Anupriya, , Zhu, Xiaowei, McCoy, Emma ORCID: 0000-0001-9033-7472 and Graham, Daniel J. (2025) Safe streets for cyclists? Quantifying the causal impact of cycling infrastructure interventions on safety. Accident Analysis and Prevention, 220. ISSN 0001-4575

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Abstract

London's Cycle Superhighways (CS) form a network of cycle routes connecting central London to outer boroughs, introduced in 2010 to promote cycling and improve safety. This paper examines their causal impact on cycling volume and safety using detailed road traffic and road safety data from the UK's Department for Transport. To estimate these effects, we employ propensity score-matched difference-in-differences and panel outcome regression models, comparing two distinct infrastructure types: segregated and non-segregated CS. A key contribution of this study is the development of a novel safety indicator — the normalised collision rate — that accounts for changes in cyclist volume (exposure) while incorporating expected non-linearities in the relationship between collisions and exposure. Our findings indicate that non-segregated CS did not increase cycling volume but led to a substantially higher collision rate. This increase appears to be driven by a post-intervention surge in the proportion of new, inexperienced cyclists along these routes. In contrast, segregated CS effectively increased cycling volume without increasing collision rates. Further, an evaluation of a major segregation upgrade along an existing non-segregated CS route revealed a notable reduction in collision rates. These results highlight the crucial role of segregated infrastructure in not only encouraging cycling but also ensuring it remains a safe and viable urban transport option.

Item Type:	Article
Additional Information:	© 2025 The Author(s)
Divisions:	Statistics
Subjects:	H Social Sciences > HE Transportation and Communications K Law
Date Deposited:	12 Aug 2025 08:42
Last Modified:	18 Aug 2025 23:16
URI:	http://eprints.lse.ac.uk/id/eprint/129112

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