There is clear data to show that 20mph limits could make a big difference to outcomes in collisions between vehicles and all vulnerable road users. It would also make walking or cycling around out neighbourhood a much more pleasant experience. 20mph ought to be the default limit near any schools, parks, playgrounds and local shops. This link gives a lot of data on the subject and why the levels of kids getting to school on foot or by bicycle are much less than many other countries. http://www.20splentyforuk.org.uk/rationale_for_20_mph.htm