Jenny Simonsen

Polycentric Multimodal Architecture (PMA) for Multimodal Traffic Management (MTA) 

Multimodal Traffic Management (MTM) is about how future traffic management can bridge the current silos within traffic management and manage the traffic across all modes (road, sea, rail, and air). Upcoming data-sharing infrastructure, advanced decision support, and coordination mechanisms must facilitate a more optimal and resilient transport system that includes connected and automated vehicles/vessels (CAVs).  

MTM can be defined by the word, as above. This is, however not sufficient when MTM solutions are to be fully understood and established. More formal and complete specifications are needed. The ORCHESTRA Polycentric Multimodal Architecture (PMA) provides such specifications according to best practices in software engineering.  

An intermediate version of the PMA is published in ORCHESTRA Deliverable D3.2

The final version of the PMA is planned for January 2024 (Deliverable D3.3). 

The PMA specifies MTM from different perspectives, such as the generic stakeholder roles involved, stakeholders’ motivations for MTM, the functionality needed by the stakeholders, the environment in which MTM will operate (surrounding systems), the information needed and shared, interfaces for information exchange, logical system components, collaboration protocols, etc.  

MTM cannot be realised as one single system. It is many systems in a distributed solution. The services needed should probably be implemented as extensions to existing traffic management systems and be part of existing organisational structures for traffic management within all modes. Thus, the PMA is not an architecture for a single system but a reference architecture for many systems. It addresses how all sub-systems should support MTM and interact and cooperate in an MTM ecosystem. 

Stakeholder roles involved 

The main stakeholder roles in the MTM ecosystem are depicted in the figure above. Some are linked to the transport part of the transport domain, and others to the traffic part. ORCHESTRA focuses on the traffic part, but MTM depends on interactions with the transport part to arrange for a resilient transport system.  

The stakeholder roles relevant to MTM associated with the transport and traffic parts are described below. Notice that the responsibilities associated with the roles may be handled by persons, systems, and persons supported by systems.  

The transport part is about the provision of transport services and the management and execution of transport operations. The stakeholder roles are: 

  • Transport Users have a person transport or freight transport demand. They use transport services provided by Transport Service Providers to fulfil the demand. 
  • Transport Service Providers offer transport services to Transport Users, and they follow up the transport chains. A chain may have several legs, and Fleet Operators deliver the associated transport operations. To arrange for MTM, the Transport Service Provider shares data on planned transports. 
  • Fleet Operators manage transport operations that carry out the requested transport tasks. Fleet Operators share data on planned and ongoing transports to arrange for MTM. 
  • Network Users are vehicles/vessels and pedestrians using the transport network. The Vessels/Vehicles may be manually operated by drivers/operators or connected and automated vessels/vehicles (CAVs). Network Users execute the transport operations managed by the Fleet Operator. They also share data on their ongoing operations to arrange for MTM, and they adapt to the measures and directions from the Traffic Orchestrator (see below). 

The traffic part is about MTM, and it aims to minimize the negative consequences of the traffic generated by the transport. The stakeholder roles are: 

  • Strategic Planning Managers may operate at an international, national, regional or local level and define the premises for the MTM in their governance area. This may, for example, include the rules and strategies to be followed when priorities are made, and decisions are taken. Strategic Planning Managers may also take concrete decisions influencing traffic management, e.g., introducing low-emission zones in cities.  
  • Traffic Orchestrators do the operative MTM and orchestrate the traffic according to the Strategic Planning Manager’s rules, strategies and decisions. Measures are taken to handle permanent and occurred and predicted and upcoming situations. Data from the stakeholders in the transport part support decisions. Traffic Orchestrators share data with the transport part and each other to arrange for coordination and proactive measures. 
  • Network Managers manage smart infrastructures and communication infrastructures that arrange real-time communication with and data collection from Network Users. 

Functionality needed by Traffic Orchestrator 

The PMA specifies functionality needed by all main stakeholders, but here we focus on the Traffic Orchestrator, which is the main role within MTM. Note that the Traffic Orchestrator role may be fulfilled by a person(a team of persons supported by systems, and that systems also automatically may carry out tasks that are well-defined according to rules.  The Traffic Orchestrator role needs: 

  • Data collection, management and governance. This is data on plans and ongoing transport operations from the transport part of the transport domain, data on traffic situations and network conditions collected by Network Users and the transport network infrastructure (sensor data, etc.), and data on capacities and situations from other networks and modes.  
  • Monitoring and analyses of traffic conditions and situations. The collected data is analysed to detect occurred and upcoming situations that must be handled. 
  • Decisions support and decision making. The situational awareness established by monitoring and analysis is input to decision support and decision-making regarding regulating the traffic and which measures should be taken. 
  • Execution of traffic orchestration. Traffic regulations are effectuated, and traffic orchestration measures that support the regulations are taken.  Two main strategies are followed, Transport Demand Management and Demand Capacity Balancing (see below). 

Transport Demand Management: When the traffic volume causes problems, the amount and type of traffic is controlled. Network Users may, for example, get access, be denied access, get priority, or be charged depending on their properties (type of vessel/vehicle, type of operation, the greenness of operation, etc.). With connected vessels/vehicles, such measures can be automated. Vessel/vehicle properties are collected electronically, and measures can be taken accordingly. Transport Demand Management may be used as a permanent measure to handle ongoing situations and implement strategic decisions (e.g., limiting access to green areas in cities) or in a dynamic way when situations occur.  

Demand Capacity Balancing: Network segments may get zero (closed) or reduced capacity due to planned or unwanted situations (maintenance, bad weather, traffic peaks, congestion, accidents, etc.). Unwanted situations should be detected as early as possible (even before they occur). In any case, traffic and traffic volumes must be adapted to the situation in a way that arranges for a resilient transport system. Measures must be taken to avoid, limit and handle potentially negative consequences. Network regulations (new speed limits, new use of lanes, etc.) and Transport Demand Management measures (access control, priorities, etc.) may be used in a dynamic way to balance the traffic volume to the capacity. Groups of, or individual, Network Users may also be asked to wait, follow directions, take another route, etc. Demand Capacity Balancing is also about coordination with other actors to transfer transports to other times, other parts of the network, other networks, and other modes. Transport Service Providers and Fleet Operators may be notified in time to re-plan their transport routes and schedules, thus limiting the negative effects. Traffic Orchestrators in other networks and modes may take measures to handle more traffic.