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Smart Motorway

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Smart Motorway
Early Morning Traffic on the M42 Motorway - Geograph - 86205.jpg
Variable speed limits in use on the M42
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Ramp Metering • Motorway
Related Terms
Active Traffic Management • Managed Motorway
This page may need updating or rewriting for the reason stated below. If you have the knowledge, please consider updating!
This list is not exhaustive, although all schemes in the "future planned developments" section were incomplete at the time of writing. A Highways Agency map of smart motorways is linked at the bottom. Only basic information is given in some places, in less detail than even the Wikipedia article!

Smart Motorways (formerly known as Active Traffic Management (ATM), Managed Motorways or Controlled Motorways) describes the modification of a motorway, usually in congested areas, with more advanced techniques to control and aid traffic flow. This either incorporates allowing traffic to drive on the hard shoulder under certain conditions (referred to as Dynamic Hard Shoulders or MM-DHS [1]) or converting the hard shoulder to a permanent traffic lane (referred to as All Lanes Running or MM-ALR). Originally referred to as Active Traffic Management, then Managed Motorways, latterly National Highways refer to these schemes as Smart Motorways.

On motorways upgraded to a Smart Motorway, more frequent overhead gantries or variable message displays are installed, emergency refuge areas (ERAs) are added to replace the loss of the hard shoulder, and variable speed limits are introduced. Signs and lights indicate if the hard shoulder is running and when to use it: sometimes the hard shoulder is used only for traffic heading off at the next junction, in other locations the hard shoulder might be converted to a running lane through the junction (known as Through Junction Running or TJR [2]).


The scheme is an expansion of existing schemes to use the motorway more effectively, such as Variable Speed Limits and Ramp Metering on motorways with variable traffic flows, where full widening might not be very cost-effective.

The first motorway to open with fully operating Active Traffic Management was the M42 between junctions 3A and 7. Plans to extend it to much of the English motorway network were announced by the Department for Transport in early 2009, and subsequently the scheme has been extended to the M6 and M40. It is an attractive political option because of its relatively low cost compared to full widening of motorways to D4M standard, which can cost more than £30m per mile widened. Concerns have been raised about the programme's safety implications as places to make emergency stops in the form of continuous hard shoulders are not available for much of the rush hour, as well as its longevity - the growth of traffic in the coming decades is likely to require more substantial widening or parallel construction at some point in the future.

Motorways being converted to Smart Motorways since 2013 will convert the hard shoulder to be a full-time running lane, as opposed to dynamic hard shoulders in previous schemes. National Highways explains this is to reduce confusion as to if the hard shoulder is open or not. [3]. The new design standards include using MS4 full-matrix variable message signs mounted at the verge more frequently than overhead gantries, however signals over each lane will be provided at on-slips and periodically on a long stretch of All Lane Running motorway. The distance between the emergency refuge areas (laybys) are also extended to up to 2.5km. [4]

How it works

On motorways converted to Smart Motorway, cameras and traffic loops are built into the motorway. When the traffic levels build up, the Highways Agency Regional Con­trol Cen­tres (RCCs) will first try and ease congestion by bringing in Variable Speed Limits. Sometimes this by itself may be enough to prevent the onset of congestion. If this doesn't work, Ramp Metering may also be switched on, if available.

If congestion is still building up, on schemes with a Dynamic Hard Shoulder, the RCC prepares to activate the hard shoulder as a traffic lane. Before doing so, a careful sweep is made to ensure the lane is clear of broken-down vehicles or other obstructions. If the Hard Shoulder is clear, overhead message boards and variable signs change to indicate the lane is open to all traffic. (If an obstruction is detected, the sequence is aborted). In some cases, the hard shoulder is purely for traffic exiting at the next junction; at other times, it becomes a normal lane of the motorway.

When the hard shoulder is closed, either a red X (without the flashing lights) or a blank overhead sign appears above the lane. [5]

In an emergency, the gantry or overhead message signs are used to show which lanes are closed and to move traffic away from obstructions.

Current Smart Motorways

Key: DHS: Dynamic Hard Shoulders, ALR: All Lane Running, VSL: Variable Speed Limits, MTR: Ramp Metering, TJR: Through Junction Running

Image Road Junctions Elements Installed Notes
M1 widening J9 - Coppermine - 18695.jpg Chopsticks icon.png M1 6A - 10 VSL Equipment already installed in 2008 widening.
M1, southbound - Geograph - 4730118.jpg Chopsticks icon.png M1 10 - 13 DHS, VSL December 2012 ALR between Toddington services and J12. Planned ALR conversion to be completed by 2023-2024 (tax year).
Chopsticks icon.png M1 16 - 19 ALR, VSL February 2018
Chopsticks icon.png M1 23a - 24 VSL February 2019 In conjunction with J24 - J25 ALR scheme
Chopsticks icon.png M1 24 - 25 ALR, VSL February 2019 In conjunction with J23A - J24 "Controlled motorway" scheme
Chopsticks icon.png M1 25 - 28 VSL May 2010
Chopsticks icon.png M1 28 - 31 ALR, VSL March 2016
Chopsticks icon.png M1 31 - 32 VSL March 2016
Chopsticks icon.png M1 32 - 35A ALR, VSL J34 - 35A opened to traffic in December 2016, J32 - J34 opened in Spring 2017.
Lane drop through J34 complex.
Chopsticks icon.png M1 39 - 42 ALR, VSL December 2015
Chopsticks icon.png M3 2 - 4A ALR, VSL July 2017
Chopsticks icon.png M4 19 - 20 DHS, VSL Spring 2014 In conjunction with M5 J15 - 17
Chopsticks icon.png M5 4A - 6 ALR, VSL June 2017
Chopsticks icon.png M5 15 - 17 DHS, VSL Spring 2014 In conjunction with M4 J19 - 20
Chopsticks icon.png M6 2 - 4 ALR, VSL March 2020
Chopsticks icon.png M6 4 - 5 DHS, VSL, MTR, TJR (J4A west only) November 2009
Chopsticks icon.png M6 5 - 8 DHS, VSL, TJR Spring 2013 Strengthening of the hard shoulder took place Between September 2009 and March 2010. Highways Agency Project
M6 ATM- Geograph - 1680317.jpg Chopsticks icon.png M6 8 - 10A DHS, VSL, MTR
Chopsticks icon.png M6 10A - 11A VSL February 2016
Chopsticks icon.png M6 11A - 13 ALR, VSL February 2016
Chopsticks icon.png M6 16 - 19 ALR, VSL March 2019 Partially replaced earlier M6 J13 - J19 scheme, withdrawn in 2014.
Chopsticks icon.png M20 3 - 5 ALR, VSL May 2020 Superseded former J4 - J5 VSL scheme
Chopsticks icon.png M20 5 - 7 VSL
Chopsticks icon.png M23 8 - 10 ALR, VSL Summer 2020
Chopsticks icon.png M23 Spur 9 - 9A ALR (Airport-bound ONLY) Winter 2019 fixed 50MPH speed limit on Airport-bound carriageway only. Motorway-bound carriageway retains HS & uncontrolled 70mph limit.
Chopsticks icon.png M25 2 - 3 VSL
Chopsticks icon.png M25 5 - 7 ALR, VSL Spring 2014
Chopsticks icon.png M25 7 - 10 VSL
Chopsticks icon.png M25 10 - 16 VSL
Chopsticks icon.png M25 16 - 23 VSL
Chopsticks icon.png M25 23 - 27 ALR, VSL J23 - J25 opened April 2014, J25 - J27 opened November 2014
Chopsticks icon.png M25 27 - 30 VSL
M42 Motorway North or West at Junction 3a - Geograph - 1283022.jpg Chopsticks icon.png M40 16 - (M42) 3A VSL (Westbound only) 2009
Chopsticks icon.png M42 3 - 3A VSL (Eastbound only) 2009
M42 TJR VMS.JPG Chopsticks icon.png M42 3A - 7 DHS, VSL, MTR, TJR (J5 south only) September 2006 The original trial installation, publicly branded as "Active Traffic Management"
Chopsticks icon.png M42 7 - 9 VSL 2009
Chopsticks icon.png M60 8 - 18 ALR, VSL J8 - J10 opened March 2018, J10 - J18 opened August 2018. Part of the "Manchester Smart Motorways" scheme
Chopsticks icon.png M62 10 - 12 ALR, VSL January 2021
Chopsticks icon.png M62 18 - 20 ALR, VSL March 2018 Part of the "Manchester Smart Motorways" scheme
Chopsticks icon.png M62 25 - 26 ALR, VSL September 2013
Chopsticks icon.png M62 26 - 30 DHS, VSL September 2013

Future planned deployment

Image Road Junctions Elements Expected Start Expected Completion Notes Link
A1(M) 6 - 8 ALR
M1 10 - 13 ALR ~2022 2023-2024 (tax year) ALR upgrade of current DHSR motorway.
M1 13 - 16 ALR, VSL June 2018 Early 2022
M3 9 - 14 ALR, VSL Jan 2020
M4 3 - 12 ALR, VSL, TJR March 2017 Expected early 2022 M4 J3 - J12 is currently believed to be the longest sustained average speed check zone in the UK, over 30 miles long! Progress as of January 2021
M6 4 - 5 ALR ALR conversion of current DHSR
M6 6 - 8 ALR ALR conversion of current DHSR
M6 8 - 10a ALR ALR conversion of current DHSR
M6 15 - 15 ALR, VSL Work began March 2018 Strengthening of the hard shoulder took place Between September 2009 and March 2010
Partially replaced earlier M6 J13-J19 scheme, withdrawn in 2014
Highways Agency
M6 21a - 26 ALR, VSL March 2021 Was due to start Early 2019
M27 J4 - J11 ALR, VSL Work began January 2019 Highways Agency

The Highways Agency identified the following sections of motorway as having potential for future deployment of Smart Motorways - some sections have since been progressed to become schemes.


Smart Motorway
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M42 North - Geograph - 1573244.jpgJunction 6 - Geograph - 1573235.jpgM42 Variable Speed Limit - Coppermine - 4286.jpgM42 ATM - Coppermine - 3682.jpgM6 J10a Queue.jpg
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