‘Smart Motorway’ is a term used to describe various types of motorway that are not designed in the same way as a conventional motorway. There are three types of ‘Smart Motorway’, Controlled Motorways (CM), All Lane Running (ALR) motorways, and Dynamic Hard Shoulder Running (DHS) motorways. The characteristics of each are as follows:
Conventional Motorway (D3M)
- Overhead electronic signs display messages to drivers, such as warning of an incident ahead.
- Hard Shoulder
- No refuges
- No speed control
Controlled Motorways (CM)
- Variable and mandatory speed limits.
- Overhead electronic signs display messages to drivers, such as warning of an incident ahead
- Permanent hard shoulder.
Dynamic Hard Shoulder Running (DHS)
- Variable and mandatory speed limits.
- Overhead electronic signs display messages to drivers, such as warning of an incident ahead.
- ‘Dynamic’ Hard Shoulder
- Emergency refuges between 0.3 miles apart to 1.6 miles apart
All Lane Running (ALR)
- Variable and mandatory speed limits.
- Overhead electronic signs display messages to drivers, such as warning of an incident ahead.
- No hard shoulder.
- Emergency refuges between 0.3 miles apart to 1.6 miles apart.
Although there has been a focus on the removal of the hard shoulder on some types of smart motorway, other changes to the road infrastructure have taken place which may influence safety levels. To-date there have been three reports published that look at the safety performance and other elements of smart motorways:
- 2020 – Smart Motorway Safety – Evidence Stocktake and Action Plan (DfT)
- 2021 – Smart Motorways stocktake – First year Progress Report (NH)
- 2022- Smart Motorways stocktake – Second Year Progress Report (NH)
The analysis by National Highways demonstrates that casualty rates per vehicle mile driven are lower on all forms of smart motorway than traditional motorways. All motorways are significantly safer than single carriageway roads. Independent analysis of the data has been aided with the second year stocktake report, although not all of the data has been published to allow National highway’s work to be replicated.
Campaigners have said that the removal of the hard shoulder is intrinsically unsafe, despite other improvements made to road infrastructure versus traditional motorways. The DfT has suspended the roll-out of new schemes until five years of safety data is available.