Are smart motorways dangerous?

Highways England released the following statement to the media in January 2020 in relation to comments raising serious concerns about smart motorways
The Department for Transport is considering a range of evidence during its stocktake. We expect the results to be published shortly and to provide the most up-to-date assessment of the safety of smart motorways. We are committed to implementing any new recommendations as part of our ongoing work to make our roads even safer. Jan 2020
GOV.UK website

Government's smart motorways stocktake
A first year progress report was published in March 2021. It noted "that “overall, what the evidence shows is that in most ways, smart motorways are as safe as, or safer than, the conventional ones. But not in every way”. The report added: "technology, in the form of stopped vehicle detection, can also reduce the risk of collision between a moving vehicle and a stopped vehicle. So we are continuing to roll out this technology, too – and faster than we previously planned. We are determined to do all we can to help drivers feel safer and be safer on our roads – all our roads. While some have suggested changes, for example converting a smart motorway live traffic lane back to a hard shoulder, this would reduce their capacity by a quarter. The resulting congestion on the motorways would cause significant numbers of drivers to divert to far less safe roads, increasing the numbers of people killed and seriously injured on our nation’s roads overall. It would almost certainly increase overall danger, not reduce it". March 2021

GOV.UK website

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MPs recommend the roll-out of "smart motorways" should be paused for 5 years due to insufficient data on their safety
The Government's "Smart Motorways Stocktake", released in March 2021 as a response to widespread safety concerns over the safety of "smart motorways", had an 18 point action plan for the future of "smart motorways". This included making all new schemes into all-lane running roads (ALR) in which the hard shoulder is permanently used as an extra lane.

However a House of Commons Transport Subcommittee was set up to review the Government's rollout and the safety of smart motorways and on 2nd November 2021 its report was released. It called the decision to roll out the use of the hard shoulder as an extra lane as "premature" and said there is not enough safety and economic data to justifying continuing with the rollout plans. See a copy of the select committee's report.
GOV.UK website

Where are smart motorways?
There are about 375 miles of smart motorway in England, including 235 miles without a hard shoulder. The first sections of controlled motorway were introduced on the M25 in the 1990s. Nowadays almost the entire route around London is made up of either controlled or all-lane running sections.

Dynamic sections are currently being phased out and replaced with all-lane running type of smart motorway. They are are largely concentrated along the M6 and the M42 in the Midlands, as well as on the M62 outside Leeds and Bradford.

How are stranded vehicles detected in the nearside lane of a "smart motorway"?
> Incident detection is already in place on all smart motorways.
> Stopped vehicle detection, operational on the M25 and in construction on the M3, uses scanning radar to identify stopped vehicles, set signs and alert our control rooms. It is effective in all weathers and at all levels of traffic. However, this is just one of the systems in place on smart motorways, including CCTV, incident detection, SVD and emergency areas – to keep drivers safe. The stopped vehicle detection system employed to date uses radar technology (radio waves) to detect stationary vehicles on motorways.

Radar technology to detect stranded vehicles
Earlier this year, the UK Government said that no new sections of this kind of ("smart") motorway would be opened unless they were equipped with radar technology, to detect stranded vehicles more quickly.

What is a smart motorway?
A smart motorway is a stretch of road where technology is used to regulate traffic flow and - hopefully - ease congestion. There are three main types of "smart motorway":

Controlled, which have a permanent hard shoulder, but use technology such as variable speed limits to adjust traffic flows.

> Dynamic, where the hard shoulder can be opened up at peak times and used as an extra lane. When this happens, the speed limit is reduced to 60mph. On dynamic motorways, the overhead gantries are also used to tell drivers whether or not they can drive on the hard shoulder. A red X is displayed if a lane is closed, for example, due to an accident or breakdown, and traffic is monitored using closed circuit television.

> All-lane running roads (ALR) schemes operate in the same way, except there is no hard shoulder at all and is permanently used as an extra lane. Where the hard shoulder has been permanently removed to provide an extra lane, emergency refuge areas are provided at regular intervals for cars that get into trouble. In those cases drivers are meant to aim for the emergency refuge areas (essentially laybys) placed at intervals along the road. The concern is there is no hard shoulder at all so if a car in trouble is not able to reach an "emergency refuge area or layby" the car will be stranded in the nearside lane with a flow of traffic pounding up behind with the possibility of vehicles crashing into the stranded car with the driver and any passenger(s) inside!

Most of the concerns many drivers have with smart motorways are with the "all-lane running" type.

Alerting drivers of a stranded car - the speed with which emergency signs are posted on the gantries above the motorway as a warning of a stranded car in the nearside lane is crucial to avoiding a serious accident to a stranded car and its occupants, and indeed to other motorists.

Emergency signs on overhead gantries - all three types of "smart motorways" above use overhead gantries to direct drivers. Variable speed limits are introduced to control traffic flow when there is congestion, or if there is a hazard ahead a red X is shown closing the lane and requiring drivers to move from the nearside lane into the second or other lanes. These speed limits are monitored for driver compliance by speed cameras.