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Department of Transport and Main Roads

Smart Motorways Technologies

Some delays while driving are inevitable, but Smart Motorways technologies work to identify the cause of delays on our motorways, and proactively manage traffic to lessen its impact on the overall network.

Smart Motorways technologies used to inform motorists:

Smart Motorways technologies used to gather data or images:

Lane Use Management Signs

Lane use management signs on a motorway showing closed lanes indicated by red crosses.

Lane Use Management Signs (LUMS) are electronic motorway signs that motorists may see on an overhead gantry.

The signs can show red crosses, white arrows and speed limits which apply to the lane immediately below each sign.

A solid red cross indicates that a lane is currently closed. You must not travel in a lane when a solid red cross is displayed overhead. Lanes can be closed for a number of reasons including during roadworks or after traffic incidents. Closing lanes after an incident or during roadworks helps to:

  • improve safety by reducing the risk of further incidents 
  • give faster access for emergency or service vehicles.

A flashing red cross indicates the lane is being closed to traffic. It can also mean the lane is closed to traffic up ahead. For your safety, if a red cross is flashing above the lane you are travelling in, you should exit the lane as quickly and safely as possible.

A white arrow indicates you can enter that lane to exit the motorway.

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Ramp signalling

Ramp signalling traffic signals for vehicles entering the motorway

Ramp signals are the traffic lights you may see at a motorway on-ramp.

They are typically used during periods of high-demand where motorists may be stopped momentarily at a red light before entering the motorway.

Spacing out the entry of vehicles onto a motorway in busy periods, creates safer, smoother merging for motorists and helps reduce congestion at merge points.

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Variable Speed Limit Signs

Variable speed signs indicating the current speed limit

Variable Speed Limit (VSL) signs are the electronic speed limit signs that you may see along the side of a motorway.

These signs can help improve safety, reduce stop-start travel and avoid further accidents by slowing a motorist’s approach to a hazard such as:

  • congestion
  • queues
  • heavy traffic
  • roadworks
  • earlier incidents
  • poor visibility
  • slippery road conditions.

When the red circle is flashing, it indicates that the speed limit has changed from the normal speed for that section of the motorway. Motorists must adhere to the displayed speed limit regardless of whether the red circle is flashing or not. 

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Variable Message Signs

Variable message sign in an overhead gantry along a motorway

Variable Message Signs (VMS) are electronic signs you may see on the roadside or in the overhead gantry when travelling on a motorway.

VMS provide critical information to motorists so they can be more informed about their journey.

They can provide warnings, alerts and information about changing road conditions as well as expected travel time advice.

Closed Circuit Television

CCTV camera

Closed Circuit Television (CCTV) cameras provide imagery to the Traffic Management Centres, who use it to help detect and monitor motorway incidents, breakdowns and congestion.

CCTV images can assist Traffic Management Centres to more effectively analyse traffic conditions, confirm incidents and monitor recovery and emergency services responses.

Where a vehicle has broken down, CCTV is used to confirm the location of the road user in distress and establish what further action may be required.

Road weather monitoring stations

Road weather monitoring system

Road weather monitoring stations collect weather data such as wind speed, rain intensity, visibility and road surface conditions to help determine road conditions.

Data collected from road weather monitoring stations informs Traffic Management Centres, who use it to determine if proactive measures should be taken to keep motorists safe and moving on the motorway during inclement weather.

Vehicle detectors

Markings on the road indicate the location of the vehicle detectors embedded in the road surface

Vehicle detectors are sensors that can be embedded in the road surface or mounted on poles next to the motorway that collect information about the vehicles using the road. Vehicle detectors embedded in the road surface may not be visible to motorists.

They measure real-time volume, speed and the type of traffic (such as cars and trucks) travelling along the motorway.

Data collected from vehicle detectors inform the Traffic Management Centres who use it to manage the road and take proactive measures where needed to keep motorists safe and moving on the motorway. For example, vehicle detectors can be used to detect hazards, which can inform the need to change the speed limit as shown on Variable Speed Limit signs.

Last updated 23 December 2021