• transport
• speed reductions

Editor,—We read the editorials in the BMJ and Injury Prevention about speed limits with interest^{1, 2} and would like to share some of the Scottish experience on speed reduction.

Councils throughout Scotland are conducting trials of advisory 20 mph limits as part of a Scottish Executive initiative. In Lothian these are generally in residential areas and often linked with Safe Routes to Schools projects run by the councils in partnership with Lothian Safe Routes, SPOKES (an Edinburgh based cycle group), Lothian Health, and the police. In addition a small number of mandatory 20 mph zones exist, with proposals in Edinburgh for a city wide 20 mph limit in residential areas and on shopping streets.

Road traffic accidents (RTAs) are not spread evenly across communities, with disadvantaged children having a much worse experience of RTAs.^{3, 4} In Edinburgh the City of Edinburgh Council has made traffic calming measures in areas with high accident rates a feature of the city's road safety strategy since the early 1990s. These have been mainly engineering measures to calm traffic in more disadvantaged parts of the city. This has resulted in a reduction in speeds and a 39% reduction in reported accidents in areas calmed under the “casualty reduction” programme (compared with 29% reduction where “environmental traffic management” was the aim and 4% reduction where measures were in connection with bus priority routes). This is against a picture of relatively stable accident levels in the council area during the 1990s. This suggests that targeting areas with high accident levels can produce good results and ties in with other Scotland wide data (where increased walking and cycling was also demonstrated).⁵

Engineering measures are costly, with the council spending some £1.2 million for the “casualty reduction” programme. While it remains to be seen whether the much less expensive advisory 20 mph schemes will be of similar benefit, there are some lessons about implementing and enforcing these schemes. As these 20 mph schemes are merely advisory, they can only be enforced if motorists are driving dangerously. Anecdotal evidence from early 20 mph schemes suggest that, while speeds are in general reducing, a significant proportion of motorists have not moderated their speed. These motorists are often local residents who believe they “know the road” (Lothian and Borders Police, personal communication). This emphasises the importance of community consultation before schemes are introduced and regular feedback to the community after they are in place—in Scotland only around a third of residents have rated the consultation as sufficient. Where there is good consultation there is also a high level of satisfaction with the scheme put in place.

The Scottish Needs Assessment Programme (SNAP) has recently conducted a health impact assessment of Edinburgh's transport policy which endorses the council's transport policy as a means to promote social inclusion and reduce inequalities.⁶ The policy supports less reliance on cars and promotes walking and cycling, development of excellent public transport, and integrated land use policies for commercial and residential development.