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Modern telematic equipment allows for the implementation of advanced traffic management systems optimising traffic flows on a systemic level. This is expected to yield substantial gains in energy efficiency. |
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Technology field: Energy efficient driving |
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General information | ||||||
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Description | ||||
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Point of departure In many countries existing infrastructure has reached its capacity limits. The consequence are frequent train conflicts caused by trains running out of their slots due to delays. These conflicts are especially abundant in bottlenecks of the infrastructure, such as junctions and lines with high traffic density. They usually lead to deceleration or stopping of one or several of the trains which in turn leads to new train conflicts. This domino effect leads to a propagation of delays in the network which reduces overall performance and service quality. Traffic fluidity is also a major issue for energy efficiency since any additional stop (and subsequent acceleration) along the way requires additional traction energy. Future solution One of the most promising ways to avoid train conflicts or reduce their negative effects is an electronic conflict management on the control center level. If at the train control center the exact position of all trains in the controlled area is known, train conflicts leading to signalled stops may be foreseen at an early stage. The speed regime of the involved trains may then be modified in order to avoid the conflict or reduce its effects (delays, energy consumption through stop-and-go driving). An example for such a situation is shown in a simplified manner in Fig. 1. Figure 1: Principle of conflict management by control center
Source: IZT Technical requirements Currently, if at all this conflict management is made manually at the hierarchy level of the signal boxes. A more systematic IT based optimisation on a higher level (for a bigger area of the network) is not in place in today's infrastructure management. The operation of effective future train control systems is sketched in Figure 2.
Figure 2: Components of a train control for optimised traffic fluidity (simplified) Source: IZT As can be seen such a system required the following components:
Integration into DAS Driving recommendations received from a traffic optimisation tool at the control centre could be an interesting upgrade for on-board DAS. These recommendations could just over-rule the recommendations generated by the on-board DAS. They should be displayed in the same manner so that the driver is not confused by different types of recommendations. |
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General criteria | ||||||
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Status of development: research & experiments | ||||
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At present, no railway company has realized a train control for an optimised traffic fluidity but in some countries the required infrastructure is already in place or currently established, e.g. at DSB the TRIT telematics system has set the basis for such a system by providing for train positioning and the required communication channels. | ||||
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Time horizon for broad application: 5 - 10 years | ||||
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(no details available) | ||||
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Expected technological development: highly dynamic | ||||
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(no details available) | ||||
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Motivation: | |||||
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Raise traffic fluidity and thus capacity and punctuality | ||||
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Benefits (other than environmental): big | ||||
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Punctuality The optimisation of traffic fluidity is primarily aimed at improving overall punctuality and thus service quality. System capacity If train delays are reduced, slot management is inproved and capacity of the infrastructure can be raised. |
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Barriers: high | ||||
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Investment costs A train control system based on traffic optimisation at the control centres requires additional information and communication infrastructure both in trains and at control centres. Depending on the point of departure of an individual railway company this will cause medium to high costs. Technological Some of the IT required for an advanced traffic optimisation system is not yet available. For example an optimisation system which could handle all the position data from dozens or hundreds of trains and find the systemic optimum for their speeds is to be developed. |
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Success factors: | |||||
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Standardisation of interfaces A key success factor for the implementation of advanced telematic systems is a high degree of standardisation of interfaces. This offers two crucial advantages:
Standards are especially needed for driving advice systems allowing for a later upgrade to integrate recommendations coming froma control centre level. data formats and transmission protocols for the information exchange between trains and control centers or central servers. Once established such a radio link, there is a number of relevant information that could be exchanged, e.g.
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Applicability for railway segments: high | ||||
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Type of traction: electric - DC, electric - AC, diesel | |||||
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Type of transportation: passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines, freight | |||||
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(no details available) | ||||
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Grade of diffusion into railway markets: | |||||
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Diffusion into relevant segment of fleet: 0 % | ||||
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Share of newly purchased stock: 0 % | ||||
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(no details available) | ||||
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Market potential (railways): medium | ||||
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(no details available) | ||||
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Example: | |||||
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(no details available) | ||||
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Environmental criteria | ||||||
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Impacts on energy efficiency: | ||||
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Energy efficiency potential for single vehicle: 5 - 10% | ||||
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Energy efficiency potential throughout fleet: > 5% | ||||
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Train conflicts and have a major effect on energy consumption for train operation. Although the prominent role of traffic fluidity on energy efficiency is undoubted, there is little quantitative data on its impact. A study by Adtranz Switzerland (Meyer et al. 2000) measured the energy consumption of different real train runs between Luzern and Zurich. The figures revealed that the average energy consumption of the runs on which no unexpected stops occurred was 10-15% lower than the corresponding average of all runs with one or several unexpected stops. The authors conclude that an improved traffic situation could save up to 10 % of the energy. |
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Other environmental impacts: neutral | ||||
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(no details available) | ||||
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Economic criteria | ||||||
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Vehicle - fix costs: strongly dependent on specific application | ||||
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An advanced traffic optimisation system would require some additional information and communication on-board equipment, such as GPS units, GSM-R transmitters and a software to display driving recommendation on the drivers' desk. Some of this equipment may already be deployed for other purposes in many fleets. Therefore the vehicle fix costs heavily depend on the technological point of departure. | ||||
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Vehicle - running costs: significant reduction | ||||
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(no details available) | ||||
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Infrastructure - fix costs: strongly dependent on specific application | ||||
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Just as in the case of vehicle fix costs the required infrastructure investment strongly depends on the point of departure in a given infrastructure. | ||||
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Infrastructure - running costs: unchanged | ||||
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Scale effects: low | ||||
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(no details available) | ||||
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Amortisation: (no data) | ||||
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The amortisation time of an advanced traffic management system strongly depends on the intial investment, cf. vehicle - fix costs and infrastructure - fix costs. | ||||
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Application outside railway sector (this technology is railway specific) | ||||||
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Overall rating | ||||||
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Overall potential: very promising | ||||
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Time horizon: mid-term | ||||
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Advanced centralised traffic management systems are seen as one of the most effective instruments for raising traffic fluidity. They will improve two of the most critical quantities in today's railway operation: overall punctuality and infrastructure capacity. A very considerable increase in energy efficiency is a very important side effect. Barriers for such a system are high, since a fleet-wide roll-out of additional IT components is necessary and an integration into existing train control hierarchies is to be achieved. Given the immense benefits for service quality, infrastructure management and energy efficiency, the introduction of advanced traffic management systems will be a key success factor for the efficiency and quality of railway operation in dense infrastructures. The cost effectiveness and speed of the introduction of traffic optimisation systems strongly depends on standardised interfaces ensuring maximum synergy effects with other telematic solutions. |
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© UIC - International Union of Railways 2003 |