UK moves to lower speed5 Feb 2013
On the 18th of January 2013 the UK's Department for Transport issued new guidelines for setting speed limits. They specifically encourage traffic authorities to consider the introduction of more 20 miles per hour limits and zones.
In the UK, the standard urban speed limit is 30 mph (48 kph). However there are already more than two thousand 20 mph areas in England. The guidelines say "20 mph zones are predominantly used in urban areas, both town centres and residential areas, and in the vicinity of schools. They should also be used around shops, markets, playgrounds and other areas with high pedestrian or cyclist traffic..."
The guidelines explain that "20 mph zones are very effective at reducing collisions and injuries. Research in 1996 showed that overall average annual collision frequency could fall by around 60%, and the number of collisions involving injury to children could be reduced by up to two-thirds."
For more detail, see Setting local speed limits: Department for Transport circular 01/2013.