Question to the Department for Transport:

To ask the Secretary of State for Transport, how many miles of (a) 40mph and (b) 50mph zones have been in place on motorways in each of the last ten years.

Highways England do not hold data in the requested format. On Smart Motorways, speed limits below the national limit are set dynamically to smooth traffic flows or manage incidents so the length of 40mph or 50mph zones changes all the time. When Highways England are undertaking improvements or maintenance works, it is sometimes necessary to set a temporary speed limit below the national limit. Details on live traffic information can be tracked on Highways England’s Traffic England Website http://www.trafficengland.com/ and upcoming roadworks are available on https://roadworks.org/ .