Low Traffic Neighbourhoods in London: boundary road journey times and congestion

Low Traffic Neighbourhoods (LTNs) restrict through-traffic in residential areas. One concern is that LTNs may displace motor traffic onto nearby boundary roads, increasing journey times and congestion.,We explored this using Google Directions API data to assess how five LTNs in London affected boundary road journey times and heavy congestion. We found that journey times increased in the first year on the boundary roads of all five LTNs, with an average relative increase of 8.6% (95%CI 2.6% to 15.0%). Heavy congestion showed a similar trend, although the pooled increase was not statistically significant. Both effects reduced substantially from year 2 onwards, with average journey times and congestion typically returning to pre-LTN levels. We conclude that LTNs do not cause persistent boundary-road delays on average, although short-term disruption is likely. Policymakers should monitor outcomes over extended periods and consider targeted mitigation measures on the minority of boundary roads where long-term effects persist.