A smart motorway (formerly managed motorway), also known in Scotland as an intelligent transport system, is a section of motorway in the United Kingdom that employs active traffic management (ATM) to increase capacity. Technologies used include Motorway Incident Detection and Automatic Signalling (MIDAS), variable speed limits and variable lane control. At particularly busy times, ramp metering may be used, and some roads permit the hard shoulder to be used as a running lane.
Smart motorways were developed at the turn of the 21st century as a cost-effective alternative to traditional carriageway widening, with intended benefits ranging from shorter journey times to lower vehicle emissions.[1][2][3] However, smart motorways have received intense criticism from politicians, police representatives and motoring organisations, mainly for perceived reductions in safety, particularly regarding the removal of the hard shoulder from some sections of motorway.[4][5] Such roads are known as all-lane running (ALR) motorways, and replace the traditional hard shoulder with a full-time running lane with discrete emergency refuge areas. A 2020 government report found that ALR conversions reduced the frequency of fatal casualties, but increased the frequency of non-fatal casualties. The incidence of collisions between moving vehicles decreased, but collisions between moving and stationary vehicles increased.[6]
In April 2023, the government scrapped plans for the building of all new smart motorways, citing costs and a "lack of confidence felt by drivers" as reasons for the decision.[7]
The term controlled motorway is sometimes used for schemes that use variable speed limits without hard-shoulder running (for example, the M25 motorway between junction 27 and junction 30).
- ^ "M20 Junctions 4 - 7 Controlled Motorways". Archived from the original on 10 August 2012.
- ^ "Highways England - Our Road Network". Archived from the original on 24 December 2012.
- ^ Cite error: The named reference
Active Traffic Managementwas invoked but never defined (see the help page). - ^ "38 killed on smart motorways in last five years". BBC News. 26 January 2020. Retrieved 30 March 2021.
- ^ Allen, James (29 January 2020). "Smart motorways labelled death traps by Police Federation chairman". The Sunday Times Driving. Sunday Times Driving Limited. Retrieved 8 April 2021.
- ^ Cite error: The named reference
:0was invoked but never defined (see the help page). - ^ "All new smart motorways scrapped". GOV.UK. Retrieved 15 April 2023.