English: "3.2.3. How impacts on travel behaviour change across time, as schemes become established

Table 9 presents analyses restricted to Waves 1–3, to examine the impact of the duration of LTN implementation on the magnitude of behaviour change. These results suggest that positive effects on walking and cycling tend to increase after 1 and 2 years compared to after less than 1 year. A similar trend appears for the car travel time point estimates, although this is never statistically significant. There was likewise a tendency for an increase across Waves in several other outcomes, including the proportion of people doing any past-week cycling, the proportion of people doing 140 min/week of active travel, and the proportion of households without a car.17 Although the confidence intervals overlap, the trends shown in Fig. 4 suggest that active travel may increase, and traffic evaporation effects grow over time after an LTN has been implemented, as effects may somewhat lag intervention implementation. However, in calculating health economic benefits this has been assumed as stable, likely to be a conservative assumption."

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"Using the mean average of the point estimates, the high-dose area as a whole (combining LTN and non-LTN areas within the mini-Holland boroughs) was assumed to generate an average increase of 13.0 min of cycling and 39.9 min of walking. Repeating the analysis with point estimates for the LTN areas (including in 2020 and 2021 Covid-era LTNs in Waves 4 and 5) led to using an average increase of 21.5 min of cycling and 66.6 min of walking in the LTN areas. Note that these averages in each Wave capture impacts of infrastructure that has been in place for between 1 and 5 years. Given evidence that the impacts of LTNs may rise over time (Fig. 4) this is likely a conservative estimate.

The high-dose area generated over 20 years a health economic benefit of £1,056 m, of which £821 m came from reduced mortality due to additional physical activity. The total health economic benefit is around ten times the programme cost. Each year, there are 37 deaths avoided and 753 years of life lost (YLL) avoided, with 535,421 sick days avoided. This benefit is likely to have been concentrated within the LTN areas that saw the greatest rise in walking and cycling. For the LTN areas within the mini-Holland boroughs, the health economic benefit is £443 m, around 40% of the whole programme benefit, of which £344 m comes from physical activity benefits."