Jan 28, 2020, 07:46 AM by Robin Sutton

A smart motorway is a section of a motorway that uses traffic management methods to increase capacity and reduce congestion in particularly busy areas. These methods include using the hard shoulder as a running lane and using variable speed limits to control the flow of traffic.

 Smart Motorways were introduced nationwide after a successful pilot ended on the M42 near Birmingham in 2010. They were designed without a hard shoulder to separate drivers who break down from the normal flow of speeding traffic. In the pilot,there were safe stopping points for motorists, called emergency safety refuges, on average every 600 metres. 
 The three different types of smart motorway currently include controlled motorways, dynamic hard shoulder running schemes and all lane running schemes. 

Controlled motorways have three or more lanes with variable speed limits, but retain a hard shoulder. The hard shoulder is always available for use in a genuine emergency and unlike other forms of smart motorway retain the original concept of a continuous refuge in an emergency. Variable speed limits are displayed on overhead gantry signs - if no speed limit is displayed the national speed limit is in place. Speed limits are enforced by speed cameras. It has been reported that sudden variable speed limit changes have caused drivers to brake firmly to reduce their speed in time. Highways England have said that there is a slight lag between changing the limit and when cameras start enforcing the revised limit to allow drivers to reduce their speed at a sensible rate. However there is no specific time period given for this and it can be as quick as 10 seconds.

All lane running schemes  remove the hard shoulder and convert it into a running lane permanently. The former hard shoulder is only closed when there is an incident. Closure of the lane is shown by a red X on the gantry above meaning drivers must exit the lane as soon as possible.
All running lane motorways have overhead or verge mounted gantry signs that display the mandatory speed limit which varies depending on the traffic conditions. If no speed limit is displayed the national speed limit is in place. As with controlled motorways there is concern that sudden changes in the speed limit may cause drivers to slam on their brakes to rapidly reduce their speed.
CCTV is used extensively to monitor traffic for any incidents. Should drivers break down or be involved in an accident there are emergency refuge areas at the side of the carriageway for them to use but the average spacing is 1.5 miles apart.

Dynamic hard shoulder running is where the hard shoulder is opened for use as a normal lane for traffic to ease congestion. On these stretches a solid white line differentiates the hard shoulder from the normal carriageway. Overhead signs on gantries indicate whether the hard shoulder is open to traffic.
If the signs over the hard shoulder are blank or display a red X, it must not be used except in the case of an emergency. Other variable message signs will say ‘hard shoulder for emergency use only. A red X on the gantry above means you must exit the lane as soon as possible. Clearly ignoring the ‘red X’ sign or confusion over what a blank sign means is extremely dangerous.
Overhead gantries on these types of motorway also display the mandatory speed limit which varies depending on the traffic conditions. Speed cameras are used to enforce these - no speed limit displayed indicates the national speed limit is in place.

 Are Smart Motorways more dangerous than traditional forms? In a survey 68% of drivers thought that removing the hard shoulder made motorways more dangerous. However Highway England statistics show that personal injury incidents have reduced by a half and that journey reliability has improved by 22%.
 Other statistics are more negative. On one section of the M25, outside London, the number of near misses had risen 20-fold since the hard shoulder was removed in April 2014. In the five years before the road was converted into a smart motorway there were just 72 near misses. In the five years after, there were 1,485. A "near miss" is counted every time there is an incident with "the potential to cause injury or ill health". Fatal accidents have happened seconds after a vehicle has broken down, far too quickly for warning signs or speed limits to have provided protection and before any chance of leaving the vehicle safely. There have been instances of signs not working occasionally for extended periods of time.

Improvements are planned. The government intends to scrap dynamic hard shoulder running. Technology is improving. A car detection system - which is currently only fitted on two sections of the M25 - can spot stranded vehicles as soon as drivers break down. Currently motorists wait an average of 17 minutes to be spotted, and a further 17 minutes before they are rescued. It could be argued that rapidly spotting a stopped vehicle and therefore activating signs more quickly could help. There is clearly an argument that more escape refuges (as in the pilot scheme) could restore the separation of stopped from running traffic but how close do they need to be to become effective? Perhaps providing a continuous escape refuge would be a good option - oh! apparently they already had that and called it a hard shoulder!

What do you think - add a comment below!