Can 20mph speed limits influence liveability? A natural experiment using Microscale Audits of Pedestrian Streetscapes-Liveability (MAPS-Liveability) and Google Street View

Background: A recent meta-narrative review investigating 20mph speed limits on public health outcomes reported inconclusive findings and the limited scope of liveability investigations. Consequently, we investigated the impact of 20mph speed limit interventions on liveability using the Microscale Audit of Pedestrian Streetscapes Liveability (MAPS-Liveability) via Google Street View (GSV).

Methods: MAPS-Liveability provides a quantitative assessment of liveability and its constructs (i.e., safety, health, sustainability, inclusivity, places, education, traffic/transport, roads, and pavements) at the micro-level (i.e., street). Google Street View enabled pre- and post-implementation data collection for Belfast (n=68 streets) and Edinburgh (n=76 streets) by two independent raters, with scores calculated for total liveability and nine liveability constructs. Wilcoxon signed-rank tests (changes pre- to post-implementation), cluster analysis (identification of discrete street clusters), analysis of variance (differences within clusters) and analysis of covariance (differences between clusters) were undertaken. Clusters were mapped, street types identified, and clusters named by determining the predominant street type.

Results: In Belfast and Edinburgh, there were significant increases post-intervention for total liveability, with 57.4% (n=39) of streets in Belfast and 75% (n=57) in Edinburgh seeing positive changes. Both cities also saw significant positive increases in the liveability constructs of traffic/transport (e.g., speed signage) and places (e.g., presence of shops); with Edinburgh also seeing a significant positive increase post-intervention for pavements (e.g., quality). Cluster analysis identified three clusters “Mixed land use”, “Central Business District” and “Residential” with each showing positive changes for total liveability and the construct of traffic/transport.

Conclusion: 20mph speed limit interventions were found to positively contribute to total liveability and the specific liveability construct of traffic/transport. This was particularly the case when 20mph speed limits were implemented on streets with dense mixed land use.