Some of the most interesting work on the effects of busy roads on local communities is found in very old studies that now lay forgotten in the archives of national libraries and are not available online.
The report of A. Lassière (1976) for the UK Department of the Environment is a good example. A shorter version appears in Lee and Tagg (1976).
The hypothesis is that people adapt their perceptions about their neighbourhood and change their walking behaviour and social life as a response to the presence of motorways. This process is influenced by characteristics like age and length of residence in the affected area.
960 residents in five sites in London near motorways and in two control sites (near quiet roads) were asked to map their walking trips and social contacts, to identify the area they considered to be their neighbourhood, and to sort pack of cards with the name of local landmarks into three groups: those within their “personal neighbourhood”, those outside it, and those they did not know.
The author then calculated these variables:
1) Size adjustment: area of the “personal neighbourhood”; number of points inside the neighbourhood; and number of points known.
2) Shifting: displacement of the neighbourhood centre away from the motorway
3) “Bridging”: proportion of neighbourhood lines, points in the neighbourhood, and points known, that are located on the other side of the motorway
4) Behaviour: proportion of walking trips and social contacts across the motorway
The analysis of these variables was disaggregated by distance from the main road, age of motorway, existence and distance to pedestrian crossings, and individual characteristics.
In comparison, the famous study by Appleyard and Lintell in San Francisco looked only at some of variables in groups #3 and #4 and disaggregated results only by traffic levels.
I will show only a small sample of the study’s 59 figures. As expected, the presence of motorways leads to “bridging”, as evident in the figure below, which compares “personal neighbourhoods” near a motorway and in a control site.
The “bridging” effect decreases with distance from the motorway and with the age of this motorway. The difference between sites near very old motorways and other sites is evidence even in locations 800m away from the road.
There is also more “bridging” behaviour in locations near a pedestrian crossing:
Other results reject the hypothesis that motorways disrupt local communities. For example, the charts below show no evidence of neighbourhood size adjustment (measured here by the number of points included in “personal neighbourhoods”) or displacement away from the motorway.
Despite the mixed results, the study proposes a set of interesting indicators to assess the local effects of large roads.
Lassière, A. (1976) The Environmental Evaluation of Transport Plans. Report to the UK Department of Environment.
Lee, T., and Tagg, S. (1976) The social severance effects of major urban roads., in P. Stringer and H. Wenzel (Eds.) Transportation Planning for a Better Environment. Plenum Press, New York., pp. 267-281.