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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 |
'''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. |
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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 |
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 or All Lane Running (see below). Where additional capacity is required on the mainline through junctions, changes to junctions may take place to accommodate this (known as Through Junction Running). |
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Electronic |
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. |
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==Key operational principles== |
==Key operational principles== |
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=== Congestion management and queue protection === |
=== Congestion management and queue protection === |
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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 |
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: <blockquote>Congestion stay in lane</blockquote>If congestion is still building up, on schemes with a dynamic hard shoulder, 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:<blockquote>Use hard shoulder</blockquote>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.<blockquote>Use hard shoulder for [J11] only ''(at junctions with the local road network)'' |
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Use hard shoulder for [M5] only ''(at interchanges between motorways)'' |
Use hard shoulder for [M5] only ''(at interchanges between motorways)'' |
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''(note that the numbers in brackets would vary based on the specific location)''</blockquote>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). |
''(note that the numbers in brackets would vary based on the specific location)''</blockquote>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). |
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On controlled and all lane running 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 |
On controlled and all lane running 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. |
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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. |
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=== Incident management === |
=== Incident management === |
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During an incident, the |
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. |
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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. |
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If an incident requires the closure of a lane, the lane control sequence used is usually as follows:<ref>{{Cite web |last=Highways |first=National |date=2021-11-12 |title=Red X - National Highways |url=https://nationalhighways.co.uk/road-safety/red-x/ |access-date=2023-04-12 |website=nationalhighways.co.uk |language=en-GB}}</ref> |
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# 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. |
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# 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. |
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#* 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. |
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#* 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. |
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# 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. |
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#* 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. |
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#* 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. |
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# 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. |
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#* 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. |
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#* 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. |
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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. |
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* 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". |
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* 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). |
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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.<ref>{{Citation |title=motorway signals.LONG. 1983 |url=https://www.youtube.com/watch?v=u5FWOPU_psg |access-date=2023-04-12 |language=en}}</ref> |
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=== Comparison to conventional motorways === |
=== Comparison to conventional motorways === |
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|Always mandatory, and shown within a red circle on variable message signs. |
|Always mandatory, and shown within a red circle on variable message signs. |
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Enforced using HADECS3 cameras mounted to the side of the gantries (previously HADECS2 cameras, a design based on the Gatso, mounted behind each AMI lane control signal). |
Enforced using HADECS3 cameras mounted to the side of the gantries (previously HADECS2 cameras, a design based on the Gatso, mounted behind each AMI lane control signal). |
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|Advisory |
|Advisory speeds only - shown without a red circle (but sometimes with amber flashing lights) on variable message signs. |
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The national speed limit remains the legally enforced limit at all times. |
The national speed limit remains the legally enforced limit at all times. |
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Lane closures using Red X legends - both on lane control gantries and verge mounted signs. These are mandatory, and enforced automatically by HADECS3 cameras. |
Lane closures using Red X legends - both on lane control gantries and verge mounted signs. These are mandatory, and enforced automatically by HADECS3 cameras. |
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Where variable mandatory speed limits and lane control restrictions no longer apply, this is shown using the national speed limit symbol. |
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|Comprehensive lane control is not often provided. |
|Comprehensive lane control is not often provided. |
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Lane closures using Red X legends are only provided in areas equipped with MS1 lane control. The Red X is mandatory, but unlike smart motorways, automatic enforcement cameras are not normally installed. |
Lane closures using Red X legends are only provided in areas equipped with MS1 lane control. The Red X is mandatory, but unlike smart motorways, automatic enforcement cameras are not normally installed. |
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Where lane control gantries are not installed, "wicket" legends are used to warn of closed lanes on variable signs and signals. These do not have the same effectiveness as the Red X as they are only advisory |
Where lane control gantries are not installed, "wicket" legends are used to warn of closed lanes on variable signs and signals. These do not have the same effectiveness as the Red X as they are only advisory, and cannot be accompanied by reduced speed limits. |
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Where advisory maximum speeds and/or lane control restrictions no longer apply, this is shown using the word "End". |
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=== Introduction of all lane running schemes === |
=== Introduction of all lane running schemes === |
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In 2011-2012, design options were being worked up to provide extra capacity to the M25 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. |
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. |
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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).<ref>{{Cite web |date=15 June 2016 |title=House of Commons - All lane running - Transport Committee |url=https://publications.parliament.uk/pa/cm201617/cmselect/cmtrans/63/6306.htm |url-status=live |archive-url=https://web.archive.org/web/20161026122253/https://publications.parliament.uk/pa/cm201617/cmselect/cmtrans/63/6306.htm |archive-date=26 October 2016 |access-date=12 April 2023 |website=UK Parliament}}</ref> 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 are also extended to up to 2.5km. |
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As a result, a new configuration was created, known as all lane running, where the hard shoulder is permanently converted into a running lane, to avoid the need for excessive use of electronic signalling. |
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⚫ | |||
All lane running schemes, including the two used on the M25, still include variable speed limits and lane control, but there is no visible hard shoulder at all. |
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⚫ | In 2019, a review on the safety of smart motorways was ordered by then-Transport Secretary Grant Shapps<ref>{{Cite news |date=2019-10-24 |title=Smart motorways to be reviewed over driver safety fears |language=en-GB |work=BBC News |url=https://www.bbc.com/news/uk-50169527 |access-date=2021-03-07}}</ref>. The "evidence stock-take", as it was branded, was |
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== Future == |
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⚫ | In 2019, a |
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The future of Smart Motorways looks bleak, at least in their current form. |
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It is the preferred option for increasing motorway capacity, as it is much more ecnomically viable than full widening of motorways to [[D4M]] standard, which can cost more than £30m per mile widened. However, many concernshave 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. |
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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. <nowiki>{{Agency|England}}</nowiki> explains this is to reduce confusion as to if the hard shoulder is open or not. [http://www.highways.gov.uk/our-road-network/managing-our-roads/improving-our-network/smart-motorways/the-new-design-standard-for-smart-motorways/]. 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. [http://assets.highways.gov.uk/our-road-network/managing-our-roads/managed-motorways/S130457_Smart%20motorways%20interactive%20ezine%20-%20Update%20-%20What%20you%27ll%20see.pdf] |
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== List of schemes == |
== List of schemes == |
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=== Future planned schemes === |
=== Future planned schemes === |
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* |
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==Links== |
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* [http://www.highways.gov.uk/our-road-network/managing-our-roads/improving-our-network/smart-motorways/ The Highways Agency guide to Smart Motoways] |
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* [http://www.roads.org.uk/index.php/articles/smart-motorways Roads.org.uk - Smart Motorways] |
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* [http://www.legislation.gov.uk/uksi/2015/392/made Legislation - The Motorways Traffic (England and Wales) (Amendment) (England) Regulations 2015] - Legislation allowing for provision of Emergency Refuge Areas |
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* [https://www.bbc.co.uk/news/uk-england-48783615 BBC News: How smart are National Highways's smart motorways?] (30.06.2019) |
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{{Navbox|cat=Road basics}} |
{{Navbox|cat=Road basics}} |
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[[:Category:Signage]] |
[[:Category:Signage]] |
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[[:Category:Traffic_Signals]] |
[[:Category:Traffic_Signals]] |
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⚫ |
Revision as of 16:48, 12 April 2023
{{Term Box | name = Smart Motorway | galleryname= | image = Early Morning Traffic on the M42 Motorway - Geograph - 86205.jpg | caption = Variable speed limits in use on the M42 | quick = [[Ramp Metering]]{{-}}[[Motorway]] | terms = Active Traffic Management{{-}}Managed Motorway }} 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 or All Lane Running (see below). Where additional capacity is required on the mainline through junctions, changes to junctions may take place to accommodate this (known as Through Junction Running).
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 schemes with a dynamic hard shoulder, 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 all lane running 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.
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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.[2]
Comparison to conventional motorways
Feature | Smart motorways | Conventional motorways |
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Number of lanes | Normally four lanes, but sometimes three, and occasionally more than four (e.g. M25 and M4 near Heathrow Airport).
May also be supplemented by a dynamic hard shoulder. |
Two, three, or four lanes - rarely more than four.
Most motorways that have been recently upgraded with four or more lanes have been equipped with smart technology. |
Hard shoulder | This depends on the type of smart motorway.
|
Permanent hard shoulder for emergency use only. May be discontinuous under bridges or over underpasses. |
Emergency areas | Where the hard shoulder is being temporarily used as, or has been permanently converted to a running lane, emergency areas are provided as a place of relative safety.
National Highways emphasizes that unlike lay-bys, these are for emergency use only. They contain emergency roadside telephones, and drivers are required to use the telephone to alert National Highways of their presence and obtain safety advice before attempting to rejoin the carriageway. |
Not needed due to the presence of a full-time hard shoulder, but very rarely, a few do exist. |
Variable speed limits | Always mandatory, and shown within a red circle on variable message signs.
Enforced using HADECS3 cameras mounted to the side of the gantries (previously HADECS2 cameras, a design based on the Gatso, mounted behind each AMI lane control signal). |
Advisory speeds only - shown without a red circle (but sometimes with amber flashing lights) on variable message signs.
The national speed limit remains the legally enforced limit at all times. |
Variable signs and signals | This depends on the type of smart motorway.
|
This will often depend on how busy the stretch in question is - however there are some anomalies of motorways that have been over- or underspecified.
|
Lane control | Comprehensive lane control provided - either through AMI (Advanced Motorway Indicator) lane control signals, or using lane control diagrams on verge-mounted MS4 signs.
Lane diversions and closures always accompanied with mandatory reduced speed limit - to help ensure vehicles move through safely. Lane closures using Red X legends - both on lane control gantries and verge mounted signs. These are mandatory, and enforced automatically by HADECS3 cameras. Where variable mandatory speed limits and lane control restrictions no longer apply, this is shown using the national speed limit symbol. |
Comprehensive lane control is not often provided.
Gantries with MS1 lane control signals (and in a few rare cases, AMIs) are usually only installed on stretches with four or more lanes, when approaching major interchanges, in and around major cities, or which are otherwise very busy. Where lane control is provided, lane diversion and closure symbols are accompanied with advisory speed limits, but neither lane diversions nor Lane closures using Red X legends are only provided in areas equipped with MS1 lane control. The Red X is mandatory, but unlike smart motorways, automatic enforcement cameras are not normally installed. Where lane control gantries are not installed, "wicket" legends are used to warn of closed lanes on variable signs and signals. These do not have the same effectiveness as the Red X as they are only advisory, and cannot be accompanied by reduced speed limits. Where advisory maximum speeds and/or lane control restrictions no longer apply, this is shown using the word "End". |
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 involve the concurrent use of multiple traffic management measures, tailored to the needs of individual schemes.
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.[3] 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.
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.
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).[4] 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 are also extended to up to 2.5km.
Safety concerns
In 2019, a review on the safety of smart motorways was ordered by then-Transport Secretary Grant Shapps[5]. The "evidence stock-take", as it was branded, was
Future
The future of Smart Motorways looks bleak, at least in their current form.
List of schemes
Current Smart Motorways
Key: DHS: Dynamic Hard Shoulders, ALR: All Lanes Running, VSL: Variable Speed Limits, MTR: Ramp Metering, TJR: Through Junction Running
Image | Road | Junctions | Elements | Installed | Notes | |
---|---|---|---|---|---|---|
File:M1 widening J9 - Coppermine - 18695.jpg | {{J|M1|6A}} - {{J|M1|10}} | VSL | Equipment already installed in 2008 widening. | |||
File:M1, southbound - Geograph - 4730118.jpg | {{J|M1|10}} - {{J|M1|13}} | DHS, VSL | Dec 2012 | Currently A5-M1 link roadworks going on - the ATM systems are partially inactive during this stretch. Construction due to end around 2018-2020. | ||
{{J|M1|28}} - {{J|M1|31}} | ALR, VSL | March 2016 | ||||
{{J|M1|31}} - {{J|M1|32}} | VSL | March 2016 | ||||
{{J|M1|32}} - {{J|M1|35A}} | ALR, VSL | J34 - 35A opened to traffic in December 2016, J32-34 is still under construction. Lane drop through J24. |
||||
{{J|M1|39}} - {{J|M1|42}} | ALR, VSL | December 2015 | ||||
{{J|M4|19}} - {{J|M4|20}} | DHS, VSL | Spring 2014 | In conjunction with M5 J15 - 17 | |||
{{J|M5|15}} - {{J|M5|17}} | DHS, VSL | Spring 2014 | In conjunction with M4 J19 - 20 | |||
{{J|M6|4}} - {{J|M6|5}} | DHS, VSL, MTR, TJR (J4A west only) | November 2009 | ||||
{{J|M6|5}} - {{J|M6|8}} | DHS, VSL, TJR | Spring 2013 | Strengthening of the hard shoulder took place Between September 2009 and March 2010. Highways Agency Project | |||
File:M6 ATM- Geograph - 1680317.jpg | {{J|M6|8}} - {{J|M6|10A}} | DHS, VSL, MTR | ||||
{{J|M6|10A}} - {{J|M6|11A}} | VSL | February 2016 | ||||
{{J|M6|11A}} - {{J|M6|13}} | ALR, VSL | February 2016 | ||||
{{J|M23|8}} - {{J|M23|10}} | ALR, VSL | Summer 2020 | ||||
Spur | {{J|M23|9}} - {{J|M23|9A}} | ALR (Airport-bound ONLY) | Winter 2019 | fixed 50MPH speed limit | ||
{{J|M25|5}} - {{J|M25|7}} | ALR, VSL | Spring 2014 | ||||
{{J|M25|23}} - {{J|M25|27}} | ALR, VSL | November 2014 | ||||
File:M42 Motorway North or West at Junction 3a - Geograph - 1283022.jpg | {{J|M40|16}} - {{J|M42|3A|showroad=true}} | VSL (Westbound only) | 2009 | |||
{{J|M42|3}} - {{J|M42|3A}} | VSL (Eastbound only) | 2009 | ||||
File:M42 TJR VMS.JPG | {{J|M42|3A}} - {{J|M42|7}} | DHS, VSL, MTR, TJR (J5 south only) | September 2006 | The original trial instalation, publicly branded as "Active Traffic Management" | ||
{{J|M42|7}} - {{J|M42|9}} | VSL | 2009 | ||||
{{J|M62|25}} - {{J|M62|26}} | ALR, VSL | September 2013 | ||||
{{J|M62|26}} - {{J|M62|30}} | DHS, VSL | September 2013 |
Schemes under construction
Image | Road | Junctions | Elements | Expected Start | Expected Completion | Notes | Link |
---|---|---|---|---|---|---|---|
M1 | J32 - J35A | 2010/2011 | 2011/2012 | Highways Agency | |||
M3 | J2 - J4A | November 2014 | June 2017 | Highways Agency | |||
M5 | J4A - J6 | ALR, VSL | January 2016 | November 2016 | Highways Agency | ||
M6 | J13 - J19 | DHS, VSL | After 2015 | Strengthening of the hard shoulder took place Between September 2009 and March 2010 | Highways Agency | ||
M25 | J7 - J10 | ||||||
M25 | J23 - J27 | Spring 2013 | Autumn 2014 | ||||
M60 | J8 - J18 | VSL | July 2014 | September 2017 | {{Agency|England}} | ||
M62 | J18 - J20 | ALR, VSL | July 2014 | September 2017 | {{Agency|England}} | ||
M62 | J25 - J30 |
Future planned schemes
{{Video List}}
Category:Highway Design Category:Signage Category:Traffic_Signals
References
- ^ Highways, National (2021-11-12). "Red X - National Highways". nationalhighways.co.uk. Retrieved 2023-04-12.
- ^ motorway signals.LONG. 1983, retrieved 2023-04-12
- ^ Rees, T (April 2002). "Assessment Strategy for the Active Traffic Management Pilot" (PDF). Standards for Highways. Retrieved March 9, 2021.
{{cite web}}
: CS1 maint: url-status (link) - ^ "House of Commons - All lane running - Transport Committee". UK Parliament. 15 June 2016. Archived from the original on 26 October 2016. Retrieved 12 April 2023.
- ^ "Smart motorways to be reviewed over driver safety fears". BBC News. 2019-10-24. Retrieved 2021-03-07.