A really interesting (for me, anyway) article on the law around 20mph limits and traffic calming.  I didn’t know that the law said you had to have traffic calming measures if you had a 20mph limit. (Although I’m sure some places have 20mph without traffic calming – Crossacres Road in Wythenshawe for a start).

The law seems to be that you can have a 20 mph limit without traffic calming measures, but only if the traffic is already quite slow – at least 85% of vehicles should already be going 24mph or slower.

However, the Government research is clear that 20 mph limits do work in reducing speeds and accidents (though not in getting everyone to drive slower that 20 mph).

average speeds reduced by 9 mph, annual accident frequency fell by 60%, the overall reduction in child accidents was 67%, and there was an overall reduction in accidents to cyclists of 29%. Traffic flow in the zones was reduced by 27%, but flows on the surrounding boundary roads increased by 12%. There was generally little accident migration to surrounding roads.

The Government advice on introducing 20mph zones is here.  I’ll be interested to read up on the details: certainly I agree with the author of article that any community should have all the information as early as possible.