asked Her Majesty's Government:

What percentage of the local highway authority road network in England and Wales is currently subject to a 20-miles-per-hour speed limit. [HL2976]

This information is not held by the Department for Transport. Local traffic authorities are responsible for setting local speed limits and have powers to introduce 20 mph speed limits and 20 mph zones without consent from the Secretary of State. They are not required to inform the department whenever they change a speed limit.

The department has recently commissioned a new research project on local road safety policy and practice, and some information about the implementation of 20 mph zones will be collected from local authorities as part of this study.

asked Her Majesty's Government:

What assessment they have made of the number of lives potentially saved by more widespread use of 20-miles-per-hour speed limit. [HL2977]

The Transport Research Laboratory conducted two reviews of 20 mph zones in 1996 and again in 1998. The 1996 review found that 20 mph zones which incorporated traffic-calming measures achieved an average 9 mph reduction in vehicle speeds, annual accident frequency fell by 60 per cent and overall reduction in child accidents of 67 per cent.

The 1998 review looked at wider issues in terms of vehicle speeds and included 20 mph zones and 20 mph limits where there was lesser or no traffic calming. This found reductions in vehicle speeds were minimal in 20 mph speed limits as these only require repeater signs to be used.

The Department for Transport has however recently commissioned a new research project on local road safety policy and practice, and some information about the implementation of 20 mph zones will be collected from local authorities as part of this study.