Saturday, July 08, 2017

Highways England trialling different variable speed limits

Anyone driving on the M3 last week may not have realised it but they were taking part in a secret test of variable speed limits. Highways England said that though it didn’t publicise the fact, it was testing an increase from 50mph to 55mph on the new smart motorway section in Surrey and Hampshire.


Highways England is trialling different variable speed limits for certain road conditions, such as roadworks, traffic congestion and accidents. If the tests are successful, we could be seeing more variety than the standard 50 mph usually imposed as a traffic speed management measure.

Secret tests

The test took place after the government asked Highways England to observe the impact of increasing the daytime speed limits on motorways, as drivers continue to complain that they are slow and causing delays that are often unnecessary.

The agency confirmed that the speed signs were changed from 50 to 55 mph for a short time as part of a new review of speed limits taking place around the country. Construction unions, however, are concerned by the move, saying that higher speeds could lead to more accidents involving road workers, especially at night.

Not so smart motorway

This was also the first sign that the new smart motorway was operating in its designed manner, after initially being opened as a smart motorway that wasn’t so smart – with the technology being switched on ‘shortly afterwards.’ The upgrade to a 13.4-mile section of the motorway from the M25 to Farnborough has added an extra lane and work was completed on time, with the extra lane operating for traffic as scheduled. However, the smart element of the motorway was running a little behind. This led to a 50mph speed limit being kept in place.


The smart motorway concept is said to give drivers better information about road conditions ahead of them and allow everyone to enjoy a smoother journey. It is also designed to add extra capacity, thereby improving journey times and making the motorways safer.

Cynics argue that smart motorways are “money-making roads” that contain speed cameras every few hundred yards to catch out drivers who break variable speed limits or the national speed limit. The government earned £1.1 million from smart motorway fines alone in 2015. That figure is growing by 20% annually as the smart motorway network expands and is estimated to reach £2 million a year  in earnings by 2018.

Benefits of variable speed limits

This isn’t the first time variable speed limits have been trialled on UK roads – a well publicised test on the M1 that limited the speed to 60mph is one example of a trial of the idea that has been paired with smart motorway technology.

One of the potential benefits of variable speed limits is the reduction in air pollution and therefore the easing of harmful emissions in the air from cars. The move is part of a series of steps that the National Institute for Health and Care Excellence (NICE) has suggested to reduce the effects of air pollution on health across the UK.

There are around 25,000 deaths every year in England that cite air pollution as a contributing factor – around 5% of all deaths. The health watchdog has offered a series of measures it believes will help reduce this number.

Reducing pollution

Alongside variable speed limits on motorways, NICE also suggests promoting smoother driving, building homes further away from the road and adding hedgerows to help protect cyclists on cycle paths.

Speed bumps, a current favourite with local authorities, are less favourable, as there is a chance they increase emissions rather than reduce them. Another issue is the idea of ‘no-idling’ zones around schools to stop parents leaving their cars running while waiting to pick up children.

The idea of variable speed limits is that, in traffic, cars are accelerating and decelerating. This increases the amount of emissions. However, by limiting everything to 50-60mph, cars ideally proceed at a steady rate. Suggested times and locations for the measures include all the time on the M25, Sunday on the M4 and Friday evenings on the M1.

It seems that on the surface these changes are part of a wider plan to control traffic not only to ease congestion but to help the environment at the same time.

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