The Department of Transport reviewed and republished its guidance on Setting Local Speed Limits, Circular 01/06. This placed the responsibility for setting speed limits very clearly with the local authorities. The guidelines are not however rules and simply outline the aspects to take into account when setting speed limits. They also re-inforce the need to take account of vulnerable road users.
This change was the trigger for the move towards 20mph limits being set as the default for residential roads when Portsmouth became the first city in 2008 to fully implement a city-wide scheme. For a cost of just £475,000 it changed the speed limit on 1,200 roads to 20mph. As a result of this in 2009 after the first year it was able to report a 7mph reduction in average speed on the roads where previously the average was between 24 and 29mph. A result which the Dept for Transport found "statistically significant". This caused the department to rewrite its guidelines for urban speed limit in December 2009 when it encouraged all residential streets to be set at 20mph.
You may often encounter people who are far more ready to explain "Why we can't" rather than explore "How we can" when it comes to 20's Plenty. Here are some false road blocks which may be put in your way :-
You can't put in 20 mph without physical traffic calming. That is both unpopular and expensive. No-one will want it. NOT CORRECT
If you slow traffic down to 20 mph then it is obvious that journeys will take 50% longer. This will cause delays and is not acceptable. NOT CORRECT
Police won't enforce it.
The police will not enforce 20 mph. Therefore it will be ignored by motorists. NOT CORRECT
It increases Pollution
If you put in speed bumps and drivers accelerate between them, then this constant acceleration and braking does increase fuel usage. But where 20mph limits are put in place then this encourages steadier driving using less fuel with less pollution. It also encourages people to walk or cycle and therefore reducing their car-created pollution entirely. Hence it is NOT CORRECT that 20mph limits increase pollution.
All of these are myths which can be shown to be false. Click on the buttons on the left to see why they are false and the argument against them.