I have often asserted that the single most effective preventive measure for reducing motor vehicle injuries is reducing speed. A report in USA Today describes a movement in the UK to this end.

It seems appropriate that it comes from the UK because that was where I first found convincing evidence of how effective it could be. The problem then – probably 20 years ago – was that few municipalities were choosing to go this route and there was no indication of how vigorously the limits would be enforced.  In part the British move is intended to encourage bicycling and walking, but safety concerns dominate. And it is encouraging that there is broad support for imposing 20-mph limits. Already several important cities —  Oxford, Cambridge, York, Bath, Bristol, Liverpool have adopted this limit.

It is not surprising that the move is opposed by the RAC (the UK equivalent of the AAA). There is even support from central government which has reversed its  earlier position advocating that lower limits apply only to few streets. In areas that have already implemented the 20 mph restriction there have been fewer injuries and deaths (although I have not seen the data).