The government has commissioned research into what the effects of cutting urban 30mph speed limits to 20mph would be. The research will be led by London University Professor Michael Maher and it is expected that it take three years to complete the research.
Robert Goodwill the Transport Minister said the research will examine the impact such a speed limit reduction on speed, collisions, casualties, modal shift [i.e. whether people switch from cars to other forms of transport]. The research will also consider air quality, best practice, road users' perceptions and effects on the quality of the environment, as well as relevant research from other countries. He also said that there were no plans to make 20mph the default speed limit, in reply to Green MP Caroline Lucas's question whether ministers had considered making 20mph the "national default speed limit".
In his written reply Mr Goodwill said: "Local authorities are best placed to determine the speed limits for their areas, based on local knowledge and the views of the community, and have the powers to do so."