4.2 TMS-01 Dynamic Lane Management

4.2.1 ITS service at a glance

4.2.2 ITS service profile

4.2.2.1 General ITS service description

Dynamic lane management (DLM) enables the number of lanes in one direction at a given point of the network to vary. Dynamic Lane Management techniques include the use of traffic guidance panels, permanent light signals, multiple-faced signs or prisms, lane lights, closing and directing installations and so on.

Dynamic lane management can be activated at fixed times or in particular conditions of heavy volumes of traffic, or in case of incidents, ad-hoc road work or other blockage on the specific lane, usually by means of variable message signs or other typologies of road signs.

To ensure that there are no blocks like broken-down vehicles or other objects on the lane or hard shoulder to be allocated, permanent video surveillance using Automatic Incident Detection is recommended, in particular for temporary activated systems (like reverse lane use).

4.2.2.2 What is the vision?

Use of the Dynamic lane management (DLM) is differentiated according to the following fundamental applications:

Tidal flow system

A tidal flow system is defined as the dynamic management of lanes for one direction on road sections. This allows operators to temporally (daytime, event-based) react to different capacity requirements in different directions of route sections. These sections are delimited by means of transition areas at the beginning and at the end of the section. In the case of tidal flow systems, suitable control measures have to ensure that the lanes are released in one direction only and that “driving in the wrong direction” is excluded. The reversible allocation of an additional lane to one direction during peak hours reduces the traffic density per lane at equal inflow of traffic and therefore traffic flow is improved while the frequency and extent of incidents are reduced at the same time.

Lane allocation at the intersection

Intersections can be involved in lane signalization as long as the cross-section and the directional allocation of the respective lanes are kept in the intersection area. An additional lane allocation on the approach to signal-controlled junctions increases the traffic capacity and reduces congestion at unchanged green periods.

The target of dynamic lane management at access points to motorways is the variable management of lanes on the main carriageway and the access ramp. On the main carriageway, the right lane is closed for through traffic while at the same time the lane is provided as an additional access lane of the ramp. Thus temporally increasing capacity demands of entering/exiting traffic with low loads on the main carriageway are taken into account.

Lane allocation before and in the tunnel

The possibilities and application areas for dynamic lane management at entry links to and inside tunnels should guarantee safe and smooth traffic use of the tunnels as far as possible, both in the normal case and in case of incidents, construction and maintenance works. With this aim the traffic is guided on to the counter flow lane, the so-called counter-flow operation, and guided together with the traffic in the contra-flow tube lane in case of closures in the tunnel or total closure of a tunnel tube.

Hard shoulder running

Temporary hard shoulder running provides a significant capacity increase of the crossroad section. In order to exploit the benefits of the higher capacity of hard shoulder usage, and to minimize the safety loss due to the removal of the hard shoulder, certain preconditions have to be fulfilled before the release (technical equipment, proof of economic efficiency, provision of emergency stops, infrastructure conditions).

Lane clearance ahead of road-works sites

Variable message signs (VMS) or dynamic prisms are used here to protect work teams on the roads/ motorways. This use of VMS or dynamic prisms for dynamic lane management (DLM) helps to keep traffic flowing smoothly because drivers know what is happening some hundred metres ahead of the road works site and have enough time to change lane without the need to brake. Furthermore, this procedure represents an additional element of safety for road workers.

Lane clearance due to incidents

For this typology of dynamic lane management (DLM) existing VMS are used to guide traffic from the lane impacted to neighbouring lanes in advance of the incident location and thus to assist police on the road/motorway. Agreements should be concluded with Police, Traffic Officers or rescue staff (according to the system applied in each country) in order to activate VMS and to agree in advance the content of the messages on the VMS.

4.2.2.3 What is the mission?

The overall objectives of Dynamic Lane Management (DLM) services are:

• to optimize the capacity of existing roads by using dynamic devices that affect vehicle flow by assigning the number of lanes that are open or the types of vehicles which are authorized,
• to achieve a temporary clearance of lanes in case of accidents, incidents, maintenance work or construction measures (safeguarding of lanes),
• to allocate lanes on black spot areas (bridges or tunnels) or at locations with poor safety records.

In most cases, Dynamic Lane Management provides options for road managers with a temporary increase or decrease of road sections (working sites and incidents are exceptions to ensure the safety for road users). DLM is meant to be implemented on road sections or network areas concerned with highly varying traffic loads and capacity issues.

The tidal flow system is appropriate on sections without any kind of built lane separation. Otherwise, crossover sections have to be deployed according to the network geometry, e.g. before tunnel sections.

DLM is concerned with the misuse or unclear instructions given to road users through VMS or fixed signs. Therefore, road operators should be concerned with information display with the intent to inform users in the least ambiguous way (VMS, fixed signs or traffic lights). Road operators should also focus on safety precautions before activating the DLM services.

From a global perspective, DLM measures have the positive effect of limiting congestion in a specific spot.

According to the different implementations of DLM, specific objectives are:

• Tidal flow system: The objective of tidal flow systems is to react to capacity demands on route sections for different directions (real-time or scheduled events).
• Lane allocation at exits: The objective of DLM service at exits of motorways is to variably assign the lanes of the main carriageway and the access ramp in connection with traffic demands of the two sections.
• Lane allocation before and in the tunnel: The objective of dynamic lane management before and in tunnels is to ensure safe and smooth use of tunnels as far as possible for both normal conditions as well as in the case of incidents.
• Hard shoulder running: The objective of temporary hard shoulder running is to significantly improve the capacity of the road section. When it is done with variable speed limits, the overall safety situation should be improved.
• Lane clearing ahead of working sites: The objective is to use existing and/or mobile VMS to protect work teams on the road/motorway.
• Lane clearing due to incidents: The objective is to use VMS to assist police, road operators and rescue teams on the road/motorway.

Note: Hard shoulder running is a specific application case of dynamic lane management. A dedicated ITS Core service profile describes this application, consequently the present DLM service description doesn’t present any information, requirements or recommendations dealing with this specific application. They are described in the Hard shoulder running service description (see TMS DG04). 

4.2.2.4 Distinctiveness from other ITS services

Relevant information for this service is:

• Traffic conditions status on the network
• Relevant complementary information, not included within this service profile and to be covered by other ITS Core services, is:
• Pre-trip and on-trip information services which may be used to inform users pre-trip or on-trip about the current operational status of the dynamic lane management service (see TTIS-01 and TTIS-02),
• Hard Shoulder Running is a special application case of dynamic lane management. A dedicated
• ITS Core service section describes this application (see TMS-04),
• Information provision should be coherent with Traffic Management Plans (TMP, see TMS-07) initiated by road authorities or traffic management centres, with Incident Management Information (TMS-06) and Overtaking Ban Information (TMS-05).

4.2.3 Harmonization requirements and advice

4.2.3.1 ITS service definition

“Dynamic lane management (DLM) service enables a temporally modifiable allocation of lanes by means of traffic guidance panels, permanent light signals, multiple-faced signs, LED road markers, closing and directing installations, etc.

Fundamental applications of this service are: tidal flow systems, lane allocation at intersections, lane allocation at tunnels, hard shoulder running.”

Dynamic lane management (DLM) provides a way of optimizing the capacity of existing roads by using dynamic devices that affect vehicle flow by assigning the number of lanes that are open or the types of vehicles that are authorized.

The service is mainly applicable along the network characterised by:

• flow-related problems (daily or seasonal) and/or
• safety problems

The additional following main parameters are generally taken into consideration for the deployment of this service:

• the traffic flow
• the period
• the presence of particular critical events.

Dynamic lane management can be deployed on motorways, 3 or 4 lane roads, corridors, peri-urban motorways, critical spots. In most cases (if not in the standard case) DLM is a part of a traffic control system and needs to be coordinated with other systems (i.e. speed limit, incident warning, hard shoulder running, HGV overtaking ban).

4.2.3.2 Functional requirements and advice

4.2.3.2.1 Functional architecture

Figure 44 shows the interface architecture of the Dynamic Lane Management service.

Figure 45 shows the typical functional and information architecture of the Dynamic Lane Management service.

Functional requirement:

• FR1: Dynamic lane management service implementation should be carried out the following functional decomposition into sub-functions:
  • Carry out an advisability study
  • Prepare the Dynamic lane management implementation
  • Collect and analyse data transmitted from monitoring systems
  • Monitoring
  • Decide the relevant Dynamic lane management implementation strategy to apply
  • Traffic guidance to road users
  • Track the decision for assessment use
  • Evaluate and assess, measure the impacts in order to provide recommendation and improvement (if possible)

4.2.3.2.2 Functional requirements and advice

Sub-function “Prepare implementation”

Functional requirements:

• FR2: An analysis of traffic flows and current and required infrastructure may be carried out before implementing the service to define whether it is needed or not, if it will bring benefits to traffic efficiency and if it is feasible
• FR3: Physical layout – the following items shall be taken into account:
  • acceleration and deceleration ramps should be long enough to let vehicles have the time to check the carriageway before entering it, without causing queues
  • enough lay-bys should be available to allow vehicles to stop in case of emergency when lanes are allocated (especially for hard shoulder running)

Sub-function “Data collection and analysis”

This sub-function includes traffic monitoring and road clearance control. The devices and methodologies for traffic data collection are not covered by this service description. They depend amongst others on the particular used data collection system and are left to the operator to select.

Functional requirements:

• FR4: Monitoring: infrastructure and control equipment should be used to monitor the traffic conditions and regulate traffic flows. Monitoring data collection system (also CCTV) should be able to detect real-time vehicle flow and speed.
• FR5: Road clearance monitoring: before applying any dynamic lane management (DLM), it must be verified that no car is stopped on the dynamic lane or in lay-bys from where no signs are visible (done by video-cameras and/or police or alternative technologies where appropriate).
• FR6: The clearing process should take place by controlling lane availability. This can be done for the whole section or in stages. To start the clearing process, particularly with lane safeguarding, a yellow/white lane divert arrow (with or without flashing lights) should be used as transition signal, before lane closure signs (red crosses) are used in advance of the incident site.
• FR7: Site investigation: local control devices must be connected to a traffic control centre. Operators in the traffic control centre must have access to an interface to remotely monitor traffic detectors and activate all VMS on the carriageway, managed by the centre itself using where applicable a decision support tool.
• FR8: Safety procedures: procedures must exist in order to apply all safety measures (before and during the DLM process). Safeguarding measures in the form of dynamic road markings, closing and guidance facilities can then be launched.
• FR9: Before the lane under control is ‘released’ for temporary use, it must be checked whether the lane concerned is available and safe to use for the corresponding traffic by means of video monitoring, police, traffic officers or alternative technologies as appropriate.

Sub-function “Traffic guidance to users”

Functional requirement:

• FR10: Traffic guidance to road users: when implementing a dynamic lane management (DLM) system, the road users must be informed about the availability of lanes by using suitable information means such as variable message signs, permanent light signs, multiple-faced signs or prisms or lane lights.

4.2.3.3 Interface requirements

Interface requirements:

• IFR1: If the Dynamic Lane Management service provides dynamic lane information at interface 1 (see Figure 44) it must provide coded information including the following elements: 
  • Type of the dynamic lane management, and, if applicable, the type of constriction
  • Location of dynamic lane management, if applicable including additional information on effected or restricted lanes and the residual number of lanes
  • If applicable start time and end time of the dynamic lane management
• IFR2: If interface 2 is implemented, the Dynamic Lane Management service must provide at interface 2 (seeFigure 44) Dynamic Lane Management information coded in C-ITS messages including the following elements:
  • the respective road signs for dynamic lane management
  • respective road signs relevant for the situation
• IFR3: When relevant, the Dynamic Lane Management service should collect at interface 3 (see Figure 44 ) C-ITS coded Probe Vehicle Data information (microscopic traffic situation) relevant to this ITS Core service.

4.2.3.4 Organisational Requirements

The implementation of Dynamic Lane Management comprises different applications:

• Tidal flow system
• Lane allocation at junctions
• Lane allocation before and in tunnels
• Hard shoulder running
• Lane clearing ahead of working sites — Lane clearing due to incidents.

Independently of the initial objectives, the expected benefits of the service mainly rely on the implementers’ involvement and the end users’ acceptance.

DLM usually involves a range of partners such as road authorities, road operators, the police, the fire brigade, ambulance services, recovery services and the media. Performance of the DLM process relies on an overall cooperation. This cooperation should be initiated some time before the operation of the DLM service to ensure service continuity and quality display of the DLM service.

Organisational Architecture

Organisational requirements:

• OR1: The organisational and operational structure of the service, as well as the role of each organisation/body and its tasks, must be defined.
•  OR2: Appropriate procedures must be defined for the activation and deactivation of the dynamic management of lanes.

4.2.3.5 Common Look & Feel requirements

The dynamic management of lanes is displayed to users by means of Variable Message Signs. When dealing with cross-border or cross-regional dynamic lane management (DLM) systems, Variable Message Signs display should be as harmonised as possible so as to be more comprehensible to users. The display is usually located overhead (VMS mounted on traffic sign gantries) or laterally in single cases (VMS mounted on masts) besides the carriageway.

The compliance rate and the acceptance of systems with dynamic lane management (DLM) by the car drivers may vary heavily dependent on the comprehensibility of the operated switching. It should therefore be checked and improved, if needed, by a comprehensive quality control.

End-user acceptance of the system can be improved by deploying Variable Message Signs which provide users with detailed information of how to behave on the section affected by dynamic lane management (DLM). Such information, given to the users progressively, can make them feel safer: in the case of hard shoulder allocation, for instance, users should be informed in advanced that the system is active, how they can profit from an added lane opened (or in the case of HGV how they are obliged to keep to the inside lane), how they have to reduce speed, how long an additional lane is sustained and when the system reduces lane availability again. The more the system is comprehensible for users, the more they accept it.

All measures can then be considered to be successful when users easily understand them and traffic flow is kept under control.

General requirements

In the process of harmonisation, Dynamic Lane Management is part of a traffic control system and the requirements listed below are some general requirements to be fulfilled when Dynamic Lane Management is activated. It has to be considered that DLM deals with a lot of different situations and in some cases exceptions must be possible.

Common Look & Feel requirements:

• CL&FR1: The display of signs/pictograms on VMS or other end-user devices should be in accordance with prevailing national road codes and:
  • Member States which ratified the Vienna Convention MUST respect the Vienna Convention and the European agreement supplementing the convention (1st May 1971) and SHOULD consider the Consolidated Resolution on Road Signs and Signals (R.E.2).
  • Member States which did not ratify the Vienna Convention SHOULD follow the Vienna Convention and also consider the R.E.2.
• It is up to the deploying road operator to ensure that real signs are legally compliant and widely understood by the road users.
• CL&FR2: Normally every VMS must display a sign (green arrow, yellow/white deflection arrow, “end of restriction”, red cross or speed limit) over each lane when VMS is in active use. An exception to this is the use of red crosses over “hard shoulder running lanes” or special “rush hour lanes” that are not in use; in those cases there is no need to display any sign on VMS.
• CL&FR3: A yellow/white deflection arrow must be displayed before the closure of the lane (red cross) when it was opened before.

• CL&FR4: A yellow/white deflection arrow must not point towards a lane that appears closed on the next signal gantry.
• CL&FR5: The road operator must close only one lane at a time, if DLM arrangement enables the operation.

• CL&FR6: At the end of the DLM zone, normal allocation of lanes must be indicated on VMS display either by a green arrow or by an “end of restriction” sign or maximum allowed “speed limit sign”.
•  CL&FR7: When there is a wish to display both a speed limit and a green arrow over the lanes, an additional VMS should be used.
• CL&FR8: The distance between 2 VMS series should not be too long (suggestion: < 1000m).

Tidal flow system requirements

Common look & feel requirement:

• CL&FR9: On the dedicated tidal lane at least one section of the lane must be cancelled to traffic prior to DLM implementation: one on both directions.

Lane allocation before and in the tunnel

Common look & feel requirements:

• CL&FR10: VMS series must be installed so as to ensure maximum service visibility.

• CL&FR11: If lane availability within tunnels is reduced due to planned works or incidents, DLM should be activated before the tunnel entrance.
• CL&FR12: Lane allocation should remain constant within the tunnel as long as possible.

Lane clearing ahead of working sites

Common look & feel requirement:

• CL&FR13: DLM service must be activated in accordance with the local signalisation pattern

4.2.3.6 ICT Infrastructure requirements

The deployment of the dynamic lane management (DLM) requires a minimum infrastructure.

Technical requirements:

• TR1: Variable message signs or other typologies of road signs must be installed for the closure or release of lanes.
• TR2: Vehicle detectors must be installed along the main carriageway, providing information on current traffic conditions; in some cases, they are needed to decide whether to activate the DLM process
• TR3: Video surveillance (including CCTV) must be implemented for tidal flow, DLM in tunnels and for hard shoulder release.
• TR4: A control centre with competent operational software, visualization systems, reporting and report/system archiving systems must be available.
• TR5: All ICT Infrastructure described at technical requirements TR1 TR2 TR3 TR4 should be supplied with an uninterruptible power supply or/and an emergency power system to ensure the continuity of service in case the mains electricity power source fails.

4.2.3.7 Required standards and specifications

Variable message sign standards:

The most relevant standards in Europe concerning technologies and systems examined by this guideline are EN 12966-1/2/3:2005. Road vertical signs – Variable message traffic signs. These include:

• Road vertical signs – Variable message traffic signs – Part 1: Product standard
• Road vertical signs – Variable message traffic signs – Part 2: Initial type testing
• Road vertical signs – Variable message traffic signs – Part 3: Factory production control

Information provision standards:

• IPS1: If the Dynamic Lane Management service provides dynamic lane information at interface 1 (see IFR1), it must be profiled based on EN 16157-3:2019 using the DATEX II Recommended Service Profile for Dynamic Lane Management.
• IPS2: If interface 2 is implemented, Dynamic Lane Management information (see IFR2) must be profiled in an IVIM (Infrastructure to Vehicle Information Message) based on ISO 19321 using the C-ROADS C-ITS Message Profiles for the In-Vehicle Signage service, specifically the Traffic Sign Use-Case.
• IPS3: When relevant, the Probe Vehicle Data (microscopic traffic situation) information (see IFR3) should be collected, which is profiled based on ETSI EN 302 637-2 using the CAR2CAR Communication Consortium Basic System Profile. 

4.2.3.8 Level of Service Definition

4.2.3.8.1 Level of Service Criteria

Table 26 gives the Level of Service recommendations for a Dynamic Lane Management service. The background of this concept is descripted in chapter 2.6.

Table 26: Level of Service recommendations for Dynamic Lane Management

Note: Attention must be paid to Level C of “Display of traffic information (support)” because it could create information overflow if not well organised.

Each level shows a technical advancement, but a higher level is not necessarily better than a lower level.

4.2.3.8.2 Level of Service Criteria related to Operating Environment

Level of service requirement:

• LoSR1: In the case that pre-deployment surveys/evaluations provide the necessary evidence to proceed with the deployment of the ITS-service “Dynamic Lane Management”, the minimum and optimum LoS should respect the following Level of Service to Operating Environment mapping table.

Table 27: Levels of Service related to Operating Environments (see also chapter 2.5.3 and  ANNEX C)