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Smart Motorways (formerly known as Active Traffic Management (ATM) and Managed Motorways) are sections of motorway that use additional technology to improve traffic flow, sometimes alongside the use of the hard shoulder as a traffic lane to improve capacity.

Smart motorways are equipped with variable speed limits and, depending on the needs of each individual scheme, may also include hard shoulder running (the use of the hard shoulder as an additional lane) and ramp metering. Hard shoulder running can take two forms: Dynamic Hard Shoulder (DHS) or All Lane Running (ALR). Where additional capacity is required on the mainline through junctions, changes to junctions may take place to accommodate this (known as Through Junction Running or TJR). Motorways that use variable speed limits but that retain a full-time hard shoulder are referred to as Controlled Motorways (CM).

Electronic lane control signals and Variable Message Signs (VMS) play a major role on smart motorways, and smart motorways include the most advanced equipment on UK motorways. Emergency areas are provided to provide a place of relative safety when the hard shoulder is not available - these are akin to laybys, but may only be used in an emergency.

Key operational principles
The objective of smart motorways is to increase motorway capacity, and optimize the use of this capacity, without requiring lengthy and expensive carriageway widening. Technology-driven approaches are used to help manage traffic flow, and keep travelers updated with real-time traffic information.

Smart motorways are always equipped with variable mandatory speed limits, which are displayed in a red circle and are enforced by variable HADECS3 cameras. Traffic levels are continuously monitored, through loops in the road on older schemes, and through radar on newer schemes. Pan-tilt-zoom CCTV cameras are available too, allowing operators in the National Highways Regional Control Centres to monitor any part of the motorway.

Congestion management and queue protection
When traffic levels build up, variable speed limits are brought in automatically by the advanced queue protection systems. This can also be done manually by operators in the Regional Control Centres. Sometimes this by itself may be enough to prevent the onset of congestion, and can be supplemented by ramp metering where this is available. On dynamic hard shoulder schemes, the hard shoulder will remain closed in the first instance, though operators in the Regional Control Centre in charge of the scheme may prepare to open it if further congestion is predicted. Overhead VMS may encourage drivers to avoid changing lane: "Congestion stay in lane"If congestion is still building up, on DHS schemes, operators at the Regional Control Centre in charge of the scheme will be advised that extra capacity is needed. They will then prepare 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, this is done using cameras that are placed at increased frequency along the hard shoulder. If the hard shoulder is clear, the red X above it will change to a speed limit to indicate that it is open to all traffic. Overhead MS4 VMS will display a verbal message to supplement this:"Use hard shoulder"If the cause of congestion is identified to be traffic backing up from the next junction, the hard shoulder can be designated as an extended slip road (as opposed to a general running lane), and overhead MS4 VMS will instruct traffic planning to exit to move into the hard shoulder. Where the junction concerned is an interchange between motorways, the MS4 VMS may show the number of the motorway instead of the junction number. Use hard shoulder for [J11] only (at junctions with the local road network)

Use hard shoulder for [M5] only (at interchanges between motorways)

(note that the numbers in brackets would vary based on the specific location) If an obstruction is detected, the sequence is aborted, the hard shoulder remains closed, and National Highways will deal with the obstruction (for example, providing assistance to a broken down vehicle).

On controlled and ALR motorways, the hard shoulder opening sequence does not apply, as the fourth lane is available at all times. The objective is that the fourth lane will minimize the formation of queues. Variable speed limits and the message "Congestion stay in lane" are then used if any further traffic management is necessary.

If queues continue to build up, variable speed limits are lowered from 60 mph to 50 and then to 40 (the lowest speed that can be set automatically) in conjunction with VMS showing "Queue ahead" and "Queue caution" text and symbols, to protect the back of a queue and minimize waves of stop-start traffic.

Incident management
During an incident, the smart motorway system can be used to show informational and warning messages, and set speed restrictions, lane closures, and, in extreme cases, closures of the entire motorway.

On ALR motorways, a lane is often kept closed far in advance of an incident in order to allow a clear path for emergency vehicles to access the site of the incident as quickly as possible, because there is no hard shoulder available to use for this purpose. DHS motorways usually keep the hard shoulder closed for incident access whenever an incident is reported.

If an incident requires the closure of a lane, the lane control sequence used is usually as follows:


 * 1) Approaching the closure, AMI lane control signals and/or MS4 VMS first slow traffic to 60 mph and warn road users of the upcoming closure.
 * 2) One or two gantries / VMS later, the lane(s) that are about to be closed show a "lane divert" signal, while a speed limit of 50 mph or lower applies to the open lanes.
 * 3) * Where AMI lane control signals are provided, the signals above the lanes being diverted show a white arrow pointing downwards to the left or right, which indicates the lane into which traffic must merge. The signals above open lanes show a speed limit of 50 mph or lower.
 * 4) * Where MS4 VMS are used on their own, a "lane control diagram" is shown, whereby open lanes are depicted as arrows pointing straight upwards, and lanes being diverted are depicted as arrows pointing upwards and to the left or right, towards the arrow depicting the open lane into which traffic must merge.
 * 5) Another one or two gantries / VMS later, the lane(s) that are closed finally show a "red X" signal, while a speed limit of 40 mph or lower applies to the open lanes. This "red X" symbol is actively enforced by HADECS3 cameras.
 * 6) * Where AMI lane control signals are provided, the signals above the closed lanes show a "red X" with red lights flashing from side to side to attract attention. The signals above open lanes show a speed limit of 40 mph or lower.
 * 7) * Where MS4 VMS are used on their own, a "lane control diagram" is shown, whereby open lanes are depicted as arrows pointing straight upwards, and closed lanes are depicted with a "red X". Red lights flash either side of the entire lane control diagram to attract attention.
 * 8) At the end of the closure, all lanes are reopened. Sometimes the limit is raised to national speed limit immediately, other times the increase in speed is carried out in stages as slow traffic dissipates.
 * 9) * Where AMI lane control signals are provided, a speed limit (or the "national speed limit" symbol) is shown over all lanes, to signify that all lanes have reopened.
 * 10) * Where MS4 VMS are used on their own, the "lane control diagram" disappears, and a speed limit (or the "national speed limit" symbol) is shown which applies to all lanes.

Where the entire carriageway of a motorway must be closed, this is normally done at a junction to prevent traffic from being trapped on the motorway. However, some incidents are so serious that this cannot be done and the road must be closed immediately for safety reasons.


 * Where the road is closed at a junction and traffic must leave the motorway at that junction, "red X" symbols are used far in advance of the junction, to close the outer lanes sequentially and thus gradually funnel traffic into the left-hand lane. At the junction diverge, the signals and/or VMS over the closed main carriageway show a red X over all lanes, with the words "STOP - Road closed".
 * Where an incident forces a carriageway to be suddenly closed between junctions, "red X" symbols are shown over all lanes, with the words "STOP - Road closed" and traffic will need to wait until authorities arrive to give further instructions. In these cases, the incident is often so serious that it renders all lanes impossible or extremely unsafe to pass (such as major pile-ups, large vehicle fires, and large spills of oil, chemicals, or other hazardous substances).

These lane closure sequences are not new to smart motorways - they have been standard protocol on all motorway stretches equipped with lane control signals (whether AMI or MS1) since MS1 lane control signals were first used in the 1970s. Originally, the "red X" symbol did not exist, and closed lanes were shown only with red flashing lights on the signal above that lane - the "red X" was added at some point in the 1980s to reinforce the message. Also, an inverted national speed limit symbol (box with diagonal line) was used to show the end of a speed limit or lane closure - this was changed to the word "End" in the 1980s, and this is still used today on conventional motorways.

There is a very wide range of legends that can be used on VMS to deal with various incidents, and these are set out by the National Highways Policy on the use of Variable Signs and Signals. However, many of these are rarely used.

History and development
Variable Speed Limits and Ramp Metering have been trialed as individual solutions before - the former first appearing on the M25's south-western quadrant in 1995 - but smart motorways generally involve the concurrent use of multiple traffic management measures, tailored to the needs of individual schemes. Motorways that use variable speed limits but that retain a permanent hard shoulder are nowadays known as Controlled Motorways (CM).

M42 Active Traffic Management pilot
The first smart motorway scheme was launched in 2006, on the M42 between junctions 3A and 7. The scheme, branded Active Traffic Management (ATM) at the time, involved Variable Speed Limits, Ramp Metering, and a Dynamic Hard Shoulder. Additional strategies, such as variable HOV/HGV lanes, peak-time overtaking bans, variable road markings, and more, were considered too, but were never implemented. As the pilot scheme, the M42 was given bespoke new signage, indicating the start of active traffic management, and warning of variable speed limits ahead. This signage remains on the M42 today, though it cannot be seen elsewhere; all future schemes were equipped with simpler signage of a different design.

Emergency areas were situated next to the signal gantries, which were 500-800 meters apart, and the motorway was equipped with continuous street lighting,

Further rollout of Dynamic Hard Shoulder schemes
The M42 pilot scheme showed mainly positive results, and so plans to introduce similar technology to much of the English motorway network, now under the name Managed Motorways, were announced by the Department for Transport in early 2009, and shortly afterwards a scheme was introduced on the M6, also near Birmingham.

Over the next few years, until around 2012, most new smart motorways took a similar form. The M42 and M6 schemes were extended, and sections of the M1, M4, and M5 received variable speed limits and dynamic hard shoulders. However, these new schemes were slightly watered down to reduce costs. The number of emergency areas was reduced, with the spacing between them increased. The design of through-junction running was changed, with a permanent fourth lane between junction slip roads.

Meanwhile, some other motorways, that were already in the process of being fully widened to D4M standard, opened as controlled motorways with variable speed limits (retaining a full-time hard shoulder), and many full widening schemes that were still in the design stage were considered for conversion to managed motorways instead.

Introduction of All Lane Running schemes
In 2011-2012, design options were being worked up to provide extra capacity to the M25 between junctions 5 (M26) and 7 (M23), and between junctions 23 (A1(M)) and 27 (M11). Though standard procedure at the time was to install dynamic hard shoulders, it was recognized that on this stretch, the extra capacity was in such high demand that hard shoulder running would likely have been necessary for most or all of the day. As a result, a new configuration was created, known as All Lane Running (ALR), where the hard shoulder is permanently converted into a running lane, to avoid the need for excessive use of electronic signalling. ALR schemes still include variable speed limits and lane control, but there is no continuous hard shoulder at all, and the entire carriageway is open to live traffic.

Street lighting has been largely removed. Some schemes retain lighting around junctions and/or service areas (such as M1 J23a-25, where lighting has been retained on much of the southern section), while others have removed all lighting completely (such as M1 J28-J35A, where even the interchange with the M18 at J32 has no lighting at all, neither on the approach, nor on the slip roads themselves).

Public consultations were carried out, including exercises whereby drivers used a simulator to judge how they reacted to various situations that would arise on ALR motorways. Consultations were also carried out examining various legends and symbols that could be shown on VMS to advise of some of these situations.

Since 2013, ALR has been the preferred option for increasing motorway capacity, as it is much more economically viable than full widening of motorways to D4M standard. The widening of M25 J27-J30 cost about £16.2 million per mile in 2002 figures (equivalent to about £27.8 million per mile in February 2023). In contrast, the M42 J3A-J7 dynamic hard shoulder scheme cost about £9 million per mile in 2008 figures (equivalent to about £13.6 million per mile in February 2023). The new design standards include using MS4 VMS 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 areas was also extended to up to 2.5 km.

Emergence of safety concerns
Rule 275 of the Highway Code defines a "place of relative safety" as anywhere a stranded vehicle can stop that is away from the live carriageway. Traditionally, this was always the continuous hard shoulder, but examples on smart motorways include emergency areas, exits from the motorway, service areas, and sometimes hard shoulders (Controlled Motorways retain a continuous hard shoulder, dynamic hard shoulders can be used as a place to stop when closed to traffic, and All Lane Running motorways sometimes retain hard shoulders on slip roads, through tunnels, or where there was a climbing lane before the conversion to ALR).

In 2016, Parliament's Transport Committee concluded that "the All Lane Running design has been chosen on the basis of cost savings, and it is not acceptable for the Department to proceed with a less-safe design", recommending that the rollout of ALR be halted immediately, and that all future schemes be designed to the same specification as the M42 Active Traffic Management pilot, with a Dynamic Hard Shoulder and emergency areas every 500-800 meters.

Landmark ALR incidents
In May 2018, 8-year-old Dev Naran and his grandfather stopped in the dynamic hard shoulder of the M6 in Birmingham while returning from a visit to Dev's critically ill brother in hospital. The hard shoulder was open to traffic, and the car was hit, killing Dev instantly. Since then, Dev's mother Meera has been an active campaigner for road safety and has called for essential reforms on smart motorways.

In June 2019, on a section of the M1 near Meadowhall, which had been converted to ALR, a collision occurred when a HGV hit Jason Mercer and Alexandru Murgeanu, who had stopped in lane 1 following a minor collision to exchange details. Both were killed, and Jason Mercer's widow Claire has since been actively campaigning to stop and reverse the rollout of smart motorways, including raising money for legal action.

Ms Naran and Ms Mercer have successfully attracted widespread public attention about the potentially serious safety concerns of motorways with no permanent hard shoulder. BBC's Panorama released an episode in January 2020 investigating the matter.

Smart motorway evidence stocktake and action plan
In October 2019, a review on the safety of smart motorways was ordered by then-Transport Secretary Grant Shapps. The "evidence stocktake", as it was branded, was intended to gather data on the safety of smart motorways, and in turn suggest an action plan to improve this in the future. The findings and action plan were published in March 2020. Although fatality rates were measured to be lower on DHS and ALR motorways than those with full-time hard shoulders, serious injury rates were measured to be higher.

Actions proposed as part of the Action Plan include:


 * abolishing the Dynamic Hard Shoulder variant of smart motorways, citing the potential for driver confusion over whether the hard shoulder was available for traffic or not, with the long-term aim of converting these to ALR
 * ensuring stopped vehicle detection (SVD) is installed on all ALR motorways by the end of 2023 - this was completed ahead of schedule, by September 2022
 * increasing response times by National Highways traffic officers following a report of a breakdown
 * changing design standards such that "places of relative safety" on all new ALR motorways are a maximum of 1 mile apart, with an ideal average spacing of 0.75 miles.
 * constructing ten new emergency areas on the two M25 schemes (J5-7 and J23-27) and evaluating whether these reduce the number of breakdowns in live lanes
 * based on data from this trial, considering whether a national programme of retrofitting additional emergency areas on existing ALR motorways would be beneficial, where doing so would bring these motorways up to the new design standard of providing "places of relative safety" no more than a mile apart
 * conducting further investigation into four specific stretches of DHS/ALR motorway on the M6 and M1 where clusters of incidents have been reported (M6 J5-6, M1 J10-13, M1 J30-35, M1 J39-42)
 * making emergency areas more visible. This has already been done using orange surfacing, but will now include additional diagrammatic signage, with spacing close enough such that drivers will almost always be in view of a sign showing the distance to the next emergency area.
 * investing a further £5 million on public information campaigns regarding smart motorways
 * automatically displaying "report of obstruction" messages where SVD has identified a stopped vehicle
 * considering how places of relative safety can be highlighted on GPS navigation services
 * making it easier to call for help in an emergency, including promoting the "eCall" feature built into vehicles
 * automatic enforcement of "red X" signals using cameras (this is now in place)

Parliamentary review on smart motorway safety and subsequent suspension of ALR rollout
In January 2022, the Parliamentary Transport Committee, who were conducting their own investigation into the rollout and safety of smart motorways, published their final report.

This included several recommendations to the Department for Transport and National Highways to urgently improve the safety of smart motorways:

The decision to suspend the rollout of ALR until at least 2025 was considered a landmark decision by safety campaigners. Ms Naran and Ms Mercer both welcomed the decision, but Ms Mercer reiterated her wish for ALR to be permanently abolished, and for a permanent hard shoulder to be reinstated where it has been removed. Some ALR schemes were already under construction at the time the report was published (such as the M4 J3-J12); the construction of these schemes was allowed to continue to completion.
 * to ensure that the introduction of changes to the design and operation of the Strategic Road Network are subject to a formal health and safety assessment by the Office of Rail and Road (ORR)
 * to retrofit emergency areas to existing ALR motorways to bring these up to the new design standard, whereby "places of relative safety" are a maximum of 1 mile apart, with a spacing of 0.75 miles where physically possible
 * to commission the ORR to conduct an independent evaluation of the effectiveness and operation of SVD technology, including maintenance and monitoring
 * to insert the "emergency corridor" manoeuvre into the Highway Code to help emergency services and traffic patrol officers to access incidents when traffic is congested.
 * This manoeuvre is used widely in Austria, Germany, and Switzerland, where it is a legal requirement and is referred to there as the Rettungsgasse (rescue lane) in German. ASFiNAG, the agency who manage Austria's autobahns, use the slogan "Deine Lebensrettungsgasse" ("Your lifesaving rescue lane").
 * In these countries, which drive on the right, the manoeuvre involves vehicles in the leftmost lane (closest to the central reservation) pulling as far as possible to the left when forming a queue, and vehicles in all other lanes pulling as far as possible to the right.
 * Where vehicles obstruct the emergency corridor and block the access of an emergency vehicle to an incident, the emergency vehicles being obstructed have issued on-the-spot fines to drivers obstructing their path.
 * Where a hard shoulder exists, rules vary as to whether it should be used. In Austria, drivers in the rightmost lane are expected to pull into the hard shoulder (as there may already be stationary vehicles here which would hinder incident access) but Germany's rules require the hard shoulder to be kept free, unless there is not enough physical space to form an emergency corridor without using it.
 * In the context of UK motorways, where traffic drives on the left, the manoeuvre is likely to be reversed, with traffic in the rightmost lane pulling as far as possible to the right and all other lanes pulling to the left. It remains to be determined whether the manoeuvre will be encouraged on motorways with a hard shoulder, and if so, whether the hard shoulder should be used by queueing traffic or not. National Highways is working with the AA to determine how the manoeuvre can be implemented in the UK.
 * to task the ORR with evaluating how successful the 2020 action plan has been in:
 * a) reducing incidences of live lane breakdowns on all-lane running motorways;
 * b) reducing the time for which people who breakdown or stop in a live lane are at risk; and
 * c) educating drivers on what to do if they break down in a live lane
 * to pause the rollout of ALR motorways until:
 * five years of safety and economic data is available for the remaining 112 miles of ALR motorway introduced before 2020. This effectively ensures no ALR motorways will enter construction until 2025 at the earliest;
 * all the measures proposed in the 2020 action plan have been implemented and independently evaluated on all existing ALR motorways; and
 * alternative options for enhancing capacity on the Strategic Road Network have been considered
 * to pause plans to convert DHS motorways to ALR until the next Road Investment Strategy and instead trial alternative ways in which to operate the dynamic hard shoulder to reduce confusion
 * to revisit the case for controlled motorways and consider how the business case for controlled motorways compares with that for all-lane running motorways

Future
The future of Smart Motorways looks bleak, at least in their current form. In the 2022 Conservative leadership contest between Rishi Sunak and Liz Truss, Sunak committed to halting the rollout of smart motorways. Following Ms Truss's brief stint in office and Rishi Sunak's takeover thereafter, there is some speculation within the industry that he will follow through with this commitment, and thus that the rollout of ALR in its current form will not resume, even after 2025. The RAC called for hard shoulders to be reinstated, either by reintroducing DHS or by reducing capacity back to 3 lanes.

Current Smart Motorways
Key: DHS - Dynamic Hard Shoulder, ALR - All Lane Running, VSL - Variable Speed Limits, MTR - Ramp Metering, TJR - Through Junction Running

Future planned schemes
Category:Highway Design Category:Signage Category:Traffic_Signals