What is a smart highway? UK roadmap, how safe is it and why implementation is delayed


The government has chosen to delay the construction of new “smart highways” for five years, in order to gather more data on their safety.

Smart highways use road shoulders as additional lanes for traffic and reduce congestion thanks to technology.

However, they have been criticized for being unsafe and causing road deaths.

What is a smart highway?

Smart highways are highways that use technology to regulate traffic flow.

There are three main types:

  • reviewed – has a permanent shoulder like a normal highway, but uses technology such as adjustable speed limits, indicated by overhead signs, to regulate traffic flow
  • Dynamic – the hard shoulder can be converted into another lane of traffic during rush hour, with the speed limit reduced to 60 mph. The top mark will show an X on the shoulder if it is closed
  • Run on all paths – the shoulder of the road is permanently another lane of traffic, with emergency protection areas (basically siding) at regular intervals (currently every 2.5 km) that drivers can use in an emergency

In addition to informing drivers of speed limits, which are set by speed cameras, overhead signs can also warn people of future accidents or other hazards.

Where are they in England?

Most of Britain’s smart highways are located around London, the West Midlands and the North West.

There are approximately 375 miles of smart highways currently in operation, 235 of which have no shoulders.

Current UK smart highway map (Map: UK Highways)

Most of the M25 is now a smart toll road, as is the long stretch of the M1.

There are also smart toll roads at M3, M4, M5, M6, M20, M23, M27, M40, M42, M56, M60 and M62.

Another 100 miles of the all-lane smart highway currently under construction will be completed, while 57 miles of the planned route will be delayed.

This includes work on M3 between junctions 9 and 14, M40/M42 junction, M62 between junctions 20 and 25 and M25 between junctions 10 and 16.

On routes under construction, emergency shelters should be no more than 1.5 kn, and ideally 1 km apart, the government said.

Why can they be dangerous?

A review published in November found that there was not enough safety and economic data to justify building more all-lane highways today.

It is now five more years of data to be collected for this type of route, which will remain open for now.

The lack of a permanent shoulder has led critics to say drivers can get stuck in fast traffic during an emergency.

Government figures show that 38 people died on smart highways between 2014 and 2019.

Transport Secretary Grant Shapps said: ‘While our preliminary data suggest smart motorways are among the safest roads in the UK, it is imperative that we work harder to ensure that people feel safer using them’ .

But activist Claire Mercer, whose husband Jason was killed on a smart highway near Sheffield in 2019, said: BBC News:: “The only acceptable thing is to return all shoulders permanently, 24/7, on all highways.”


Matt Thompson

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