J. Aoun
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1
Moving Block (MB) and Virtual Coupling (VC) rail signalling will change current train operation paradigm by migrating vital equipment from trackside to onboard to reduce train separation and maintenance costs. Their actual deployment is however constrained by the industry's need to identify configurations of MB and VC signalling equipment which can effectively guarantee safe train movements even under degraded operational conditions involving component faults. In this paper, we analyse the effectivity of MB and VC in safely supervising train separation under nominal and degraded conditions by using an innovative approach which combines Fault Tree Analysis (FTA) and Stochastic Activity Networks (SAN). An FTA model of unsafe train movement is defined for both MB and VC capturing functional interactions and cause-effect relations among the different signalling components. The FTA is used as a basis to apportion signalling component failure rates needed to feed the SAN model. Effective MB and VC train supervision is analysed by means of SAN-based simulations in the specific scenario of an error in the Train Position Report (TPR) for five rail market segments featuring different traffic characteristics, namely high-speed, mainline, regional, urban and freight. Results show that the thresholds of the design variables depend on the considered signalling system alternative and the investigated market segment. In particular, the TPR delay threshold allowed for MB is higher than for VC. This means that to ensure a safe train movement, VC cannot absorb a TPR delay of longer than 1.5 s, which corresponds to the mainline market segment. For MB instead, the results show that the maximum TPR delay can reach 3.9 s for high-speed and freight railways. In addition, results showed that the integration of an FTA in a SAN model can provide a better understanding of the safety-performance behaviour of a system where VC showed a higher number of braking indications with respect to MB for the same TPR error failure rate. This means that for VC to effectively supervise the train separation at the same safety level as MB, we would need to have a much higher reliability of the TPR. The overall approach can support infrastructure managers, railway undertakings, and rail signalling suppliers in investigating the effectiveness of MB and VC to safely supervise train movements in scenarios involving different types of degraded conditions and failure events. The proposed method can hence support the railway industry in identifying effective and safe design configurations of next-generation rail signalling systems.
Developments in the railway industry are continuously evolving and long-term transition strategies can enable an efficient implementation of signalling technologies that provide a significant increase in network capacity and operation efficiency. Virtual Coupling (VC) advances moving block signalling by further reducing train separation to less than an absolute braking distance using train-to-train communication and cooperative train control within a Virtually-Coupled Train Set (VCTS). This paper proposes a method to develop scenario-based roadmaps based on a SWOT and hybrid Delphi-AHP multi-criteria analysis. Step-changes are identified and initially assessed in a Swimlane based on priorities and time order collected from stakeholders through a survey and further developed in a workshop. Optimistic and pessimistic scenarios are assessed regarding various factors and timelines. Step-changes are initially defined in a Swimlane and then enriched with optimistic and pessimistic scenarios to ultimately derive scenario-based roadmaps. Durations for each of the step-changes are developed into scenario-based roadmaps that can be used as an efficient tool for stakeholders to identify and solve potential criticalities/risks to the deployment of VC as well as to setup investment and development plans. The approach is applied to deliver implementation roadmaps of VC for different market segments with particular focus on mainline railways.
The COVID-19 pandemic has imposed a dramatic effect on the mobility habits of both passengers and freight in the rail sector. Since the relaxation of COVID-19 restrictions worldwide, rail transport has been revitalised gradually. However, the new normal emerges with unprecedented issues, such as changed travel behaviour, lost profits, and a lack of personnel. In this paper, we determine the arising challenges due to COVID-19 and pandemics in general and subsequently propose several solutions to tackle these challenges in rail transport. These solutions cover multidisciplinary aspects such as passenger demand management, freight demand management, service design, automation, decentralisation and advanced railway technologies. By reviewing the relevant literature on COVID-19, public transport and particularly rail transport, we synthesise and identify promising lines of research that should devote more attention to a more efficient, effective and sustainable rail transport service. This paper provides policymakers, researchers, railway infrastructure managers and undertakings with an overview and an outlook for the impacts of the pandemic crisis and similar situations. It supports decision-making with more evidence and facilitates rail transport to restore its performance and reach its societal goal.
Railway systems are complex given their interconnectivity with sub-systems wherein each contains multiple components. Virtual Coupling (VC) is a next-generation railway signalling technology that advances Moving Block (MB), also known as European Train Control System Level 3 (ETCS L3). Some pilot implementations exist for MB. However, VC is still a visionary system and involves several safety issues due to the relative braking distance between trains. Therefore, it is important to evaluate the safety of this system to understand whether it is feasible for deployment. This paper performs a preliminary safety and reliability study by introducing a fault tree (FT) model to investigate the possible causes that lead to an unsafe train movement for MB and VC. To this aim, a FT model is initially built for the MB system, considering the system configurations and interactions between wireless devices, onboard and trackside equipment. Then, the FT model of the VC system is derived on top of the one for MB and the differences are highlighted between the FT elements of the two systems.
The railway industry needs to investigate overall impacts of next generation signalling systems such as Moving Block (MB) and Virtual Coupling (VC) to identify development strategies to face the forecasted railway demand growth. To this aim an innovative multi-criteria analysis (MCA) framework is introduced to analyse and compare VC and MB in terms of relevant criteria including quantitative (e.g. costs, capacity, stability, energy) and qualitative ones (e.g. safety, regulatory approval). We use a hybrid Delphi-Analytic Hierarchic Process (AHP) technique to objectively select, combine and weight the different criteria to more reliable MCA outcomes. The analysis has been performed for different rail market segments including high-speed, mainline, regional, urban and freight corridors. The results show that there is a highly different technological maturity level between MB and VC given the larger number of vital issues not yet solved for VC. The MCA also indicates that VC could outperform MB for all market segments if it reaches a comparable maturity and safety level. The provided analysis can effectively support the railway industry in strategic investment planning of VC.
each of the quantitative criteria while a Delphi approach has gathered values for the qualitative criteria based on extensive Subject Matter Expert (SME) interviews and workshops.
A Multi-Criteria Analysis (MCA) has been setup by implementing a hybrid Delphi-Analytic Hierarchic Process (AHP) technique to weight and combine the different criteria in final performance scores of MB and VC signalling. The adopted Delphi-AHP technique has been proven to enhance collaboration among experts in selecting and weighting the criteria by means of an iterative feedback loop ending when consistent weights of relative criteria importance were achieved.
The individual analyses of single criteria show that VC outperforms MB for all market segments in terms of infrastructure capacity, system stability, energy consumption and travel demand. VC enables trains to follow each other at a distance shorter than an absolute braking distance, which can reduce headways significantly, especially if trains can move cooperatively in virtually coupled
platoons. This is also reflected in terms of system stability and energy given that the advantage of running at a shorter safe separation while continuously being informed about the speed of adjacent trains improves the capability of mitigating delay propagation and enhancing energy efficiency. An increased modal shift to railways is observed for VC, especially for the regional and freight markets where a more flexible train service would better satisfy customer needs currently poorly addressed on those segments. Deployment of VC will be slightly more expensive than MB mostly due to the need of installing ATO and V2V communication while operational costs for the two systems will be comparable. Issues and priorities identified for regulatory approval and public acceptance were judged by SMEs to be very similar for MB and VC. In terms of safety, VC scores lower than MB given the different technological maturity level and the larger number of vital issues yet to be solved.
The SMEs assigned a very high importance weight to the safety criterion, which therefore affects greatly the final result of the MCA. The MCA score is hence in favour of MB for all market segments, despite the better performance of VC forsingle criteria like capacity, stability, energy consumption and travel demand. A fairer comparison can be obtained when assuming the same maturity level of MB and VC in a future point in time. In that case, VC clearly outperforms MB for all market segments and for freight and regional in particular, given that the provided train service flexibility would facilitate larger modal shifts of the customer demand. ...
each of the quantitative criteria while a Delphi approach has gathered values for the qualitative criteria based on extensive Subject Matter Expert (SME) interviews and workshops.
A Multi-Criteria Analysis (MCA) has been setup by implementing a hybrid Delphi-Analytic Hierarchic Process (AHP) technique to weight and combine the different criteria in final performance scores of MB and VC signalling. The adopted Delphi-AHP technique has been proven to enhance collaboration among experts in selecting and weighting the criteria by means of an iterative feedback loop ending when consistent weights of relative criteria importance were achieved.
The individual analyses of single criteria show that VC outperforms MB for all market segments in terms of infrastructure capacity, system stability, energy consumption and travel demand. VC enables trains to follow each other at a distance shorter than an absolute braking distance, which can reduce headways significantly, especially if trains can move cooperatively in virtually coupled
platoons. This is also reflected in terms of system stability and energy given that the advantage of running at a shorter safe separation while continuously being informed about the speed of adjacent trains improves the capability of mitigating delay propagation and enhancing energy efficiency. An increased modal shift to railways is observed for VC, especially for the regional and freight markets where a more flexible train service would better satisfy customer needs currently poorly addressed on those segments. Deployment of VC will be slightly more expensive than MB mostly due to the need of installing ATO and V2V communication while operational costs for the two systems will be comparable. Issues and priorities identified for regulatory approval and public acceptance were judged by SMEs to be very similar for MB and VC. In terms of safety, VC scores lower than MB given the different technological maturity level and the larger number of vital issues yet to be solved.
The SMEs assigned a very high importance weight to the safety criterion, which therefore affects greatly the final result of the MCA. The MCA score is hence in favour of MB for all market segments, despite the better performance of VC forsingle criteria like capacity, stability, energy consumption and travel demand. A fairer comparison can be obtained when assuming the same maturity level of MB and VC in a future point in time. In that case, VC clearly outperforms MB for all market segments and for freight and regional in particular, given that the provided train service flexibility would facilitate larger modal shifts of the customer demand.
The scope of Virtual Coupling is analysed together with the impact on the technical and operational railway system components of interlocking, communication structures, automatic train protection, automatic train operation, railway traffic planning, and railway traffic management. For each of these components main research and development challenges are derived providing an overview of knowledge gaps and critical step-changes for the development
of Virtual Coupling. A clear distinction must be made between VCTS train protection and cooperative train operation, similar to ATP and ATO but then for virtual-coupled trains. A convoy or VCTS is a vital safety system concept that allows virtual-coupled trains to follow each other up to relative braking distances. A convoy can additionally form a platoon, which is a non-vital multitrain control concept that enables (virtually-coupled) trains to move synchronously and stable
together. The cooperative train operation system guarantees stable operation in a platoon, while the VCTS train protection system supervises the relative braking distances.
A Swimlane roadmap is developed to group step-changes into different themes and categories. This is achieved by means of a quantitative-qualitative gap analysis between current and future states in the operational, technological and business domains. A survey was distributed to stakeholders to collect priorities and time orders for each of the defined steps within the Swimlane roadmap. Optimistic and pessimistic scenarios are defined for each market segment using the SWOT analysis from MOVINGRAIL D4.1 and the cost-effectiveness analysis from MOVINGRAIL D4.2. Optimistic scenarios are based on the estimates made in the ‘White Paper on Transport’ of the European Commission (EC) regarding travel demand and CO2 emissions. Pessimistic scenarios consider a lower growth in the railway demand as well as a higher increase in CO2 emissions and capital and operational costs when compared to the optimistic scenarios (specifically a 50% less increase in rail demand and 50% more increase in CO2 emissions and costs).
Scenario-based roadmaps are developed to fulfil the EC’s vision of a more competitive, capacity effective and sustainable railway by 2050. This deliverable is based on the assumption that the strategic goals set by the EC in terms of railway demand, capacity and emissions could be met if Virtual Coupling (VC) operations will be implemented within the target year 2050. Results show that all the considered scenarios and railway market segments could achieve the timely
deployment of Virtual Coupling except in the pessimistic scenario for mainline railways where VC could be deployed not earlier than 2054. Critical issues are here the longitudinal motion control systems of the Virtually Coupled Train Sets and the integrated traffic management and cooperative train operation complexity for heterogeneous trains. These scenario-based roadmaps can be used as an efficient tool for stakeholders to identify and solve potential criticalities/risks to the deployment of Virtual Coupling as well as to plan necessary investment/development actions.
The developed roadmaps provide a long-term transition strategy defining for each rail market segment a sequence of progressive upgrades to connected and automated railways that will eventually lead to the deployment of Virtual Coupling and enable a significant increase in infrastructure capacity and operation efficiency. ...
The scope of Virtual Coupling is analysed together with the impact on the technical and operational railway system components of interlocking, communication structures, automatic train protection, automatic train operation, railway traffic planning, and railway traffic management. For each of these components main research and development challenges are derived providing an overview of knowledge gaps and critical step-changes for the development
of Virtual Coupling. A clear distinction must be made between VCTS train protection and cooperative train operation, similar to ATP and ATO but then for virtual-coupled trains. A convoy or VCTS is a vital safety system concept that allows virtual-coupled trains to follow each other up to relative braking distances. A convoy can additionally form a platoon, which is a non-vital multitrain control concept that enables (virtually-coupled) trains to move synchronously and stable
together. The cooperative train operation system guarantees stable operation in a platoon, while the VCTS train protection system supervises the relative braking distances.
A Swimlane roadmap is developed to group step-changes into different themes and categories. This is achieved by means of a quantitative-qualitative gap analysis between current and future states in the operational, technological and business domains. A survey was distributed to stakeholders to collect priorities and time orders for each of the defined steps within the Swimlane roadmap. Optimistic and pessimistic scenarios are defined for each market segment using the SWOT analysis from MOVINGRAIL D4.1 and the cost-effectiveness analysis from MOVINGRAIL D4.2. Optimistic scenarios are based on the estimates made in the ‘White Paper on Transport’ of the European Commission (EC) regarding travel demand and CO2 emissions. Pessimistic scenarios consider a lower growth in the railway demand as well as a higher increase in CO2 emissions and capital and operational costs when compared to the optimistic scenarios (specifically a 50% less increase in rail demand and 50% more increase in CO2 emissions and costs).
Scenario-based roadmaps are developed to fulfil the EC’s vision of a more competitive, capacity effective and sustainable railway by 2050. This deliverable is based on the assumption that the strategic goals set by the EC in terms of railway demand, capacity and emissions could be met if Virtual Coupling (VC) operations will be implemented within the target year 2050. Results show that all the considered scenarios and railway market segments could achieve the timely
deployment of Virtual Coupling except in the pessimistic scenario for mainline railways where VC could be deployed not earlier than 2054. Critical issues are here the longitudinal motion control systems of the Virtually Coupled Train Sets and the integrated traffic management and cooperative train operation complexity for heterogeneous trains. These scenario-based roadmaps can be used as an efficient tool for stakeholders to identify and solve potential criticalities/risks to the deployment of Virtual Coupling as well as to plan necessary investment/development actions.
The developed roadmaps provide a long-term transition strategy defining for each rail market segment a sequence of progressive upgrades to connected and automated railways that will eventually lead to the deployment of Virtual Coupling and enable a significant increase in infrastructure capacity and operation efficiency.
A SWOT analysis is presented which builds on the outcomes of the survey, the operational scenarios and brainstorming sessions with experts of the European railway industry. The main strengths identified for VC are a substantial increase in capacity and reduced operational costs with respect to Moving Block while mitigating delay propagation and improving reliability of ground/train communication. On the other hand, weaknesses of this concept refer to the fact that capacity gains at diverging junctions equipped with current switch technologies might be marginal, since here trains still need to be separated by a full braking distance. Also, the implementation of VC operations would require an investment to upgrade the overhead line system, platform lengths (to allow platoons of trains to stop) and possibly the switch technology. An upgrade of the switch technology towards faster and more reliable ones (e.g. Railtaxi and REPOINT) will unleash the full potential of VC operations. Significant opportunities will be brought about Virtual Coupling such as potential increase in the profit of infrastructure managers and operators as well as a deregulation of the current railway market which could be opened also to smaller transport operators due to the increase of available train paths and the decrease of operational costs by full train automation. In addition, the train-to-train communication could lead to the institution of cooperative consortia of railway operators which can be more economically beneficial than the current competitive market model. This would also provide the chance to migrate obsolescent command and control systems towards future-proof digital railway architectures. Possible threats to the introduction of this concept mainly relate to potential increase of train control complexity increasing risks of approval from the railway industry. The need for an initial investment might be not well received by infrastructure managers and local governments. As well as the necessity of partially changing policies, operational procedures and engineering rules currently in place. When overcoming such challenges, Virtual Coupling has potentials to fully revolutionise and improve current train operations so to induce a sustainable shift to railways. ...
A SWOT analysis is presented which builds on the outcomes of the survey, the operational scenarios and brainstorming sessions with experts of the European railway industry. The main strengths identified for VC are a substantial increase in capacity and reduced operational costs with respect to Moving Block while mitigating delay propagation and improving reliability of ground/train communication. On the other hand, weaknesses of this concept refer to the fact that capacity gains at diverging junctions equipped with current switch technologies might be marginal, since here trains still need to be separated by a full braking distance. Also, the implementation of VC operations would require an investment to upgrade the overhead line system, platform lengths (to allow platoons of trains to stop) and possibly the switch technology. An upgrade of the switch technology towards faster and more reliable ones (e.g. Railtaxi and REPOINT) will unleash the full potential of VC operations. Significant opportunities will be brought about Virtual Coupling such as potential increase in the profit of infrastructure managers and operators as well as a deregulation of the current railway market which could be opened also to smaller transport operators due to the increase of available train paths and the decrease of operational costs by full train automation. In addition, the train-to-train communication could lead to the institution of cooperative consortia of railway operators which can be more economically beneficial than the current competitive market model. This would also provide the chance to migrate obsolescent command and control systems towards future-proof digital railway architectures. Possible threats to the introduction of this concept mainly relate to potential increase of train control complexity increasing risks of approval from the railway industry. The need for an initial investment might be not well received by infrastructure managers and local governments. As well as the necessity of partially changing policies, operational procedures and engineering rules currently in place. When overcoming such challenges, Virtual Coupling has potentials to fully revolutionise and improve current train operations so to induce a sustainable shift to railways.