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   Automatic train control  evaluated  
State-of-the-art information and communication technologies allow for an automated driverless operation of insular mass transit systems. In long-term such options exist for railway operation in general. Energy efficiency effects can be achieved through general optimisation of driving style and traffic flows.
Technology field: Energy efficient driving
close main section General information
  close sub-section Description

By means of today’s information and communication technologies, the operation of metro systems can already be fully automated. An automated driverless operation of main lines does not meet any insuperable barriers and could be an option in very long-term perspective. The main driver for automation is the superior cost-effectiveness of train operation.

Different degrees of automation can be discerned:

  1. semi-automation with reduced driver control
  2. fully automated control as the sole operating system for driverless vehicles on autonomous, separate tracks
  3. fully automated driverless trains sharing a “mixed” infrastructure with driver-operated vehicles
  4. fully automated control as the sole operating system

Level 1 and 2 have already been realised, level 3 and 4 are subject to research and development efforts.

Automated train control could have strong implications for energy efficiency, since driving patterns of the involved trains can be optimised with respect to energy consumption. This includes

  • coasting and speed optimisation
  • in metro systems with frequent stops and high train density, timetables can be designed in such a way that acceleration of one train is synchronised with braking of previous (or other) train in order to ensure a maximum use of brake energy recovery.
  • Permanent real-time traffic optimisation in order to minimise train conflicts and “red signals”.
  • Traffic fluidity and system capacity can be further improved by moving block systems.

An automated driverless operation is discussed for both freight and passenger operation. Driverless systems in freight operation are addressed in the context of self-propelled freight cars. Therefore the present evaluation focuses on the automated operation of passenger trains.

close main section General criteria
  close sub-section Status of development: in use
    Driverless train operation is in use in many people mover systems on airports and other sites throughout the world. Some metro lines have also been automated including Metro Line 14 in Paris.
  Time horizon for broad application: in > 10 years


  Expected technological development: highly dynamic

Present and future research and development for train automation has to address the following areas:

  • Recognition of foreign objects (on a wide size scale down to small—sized objects)
  • Powerful collision sensors detecting external impacts in wheel area and triggering instant emergency braking
  • Vehicle diagnostics including permanent monitoring of train parameters such as train integrity or wheel conditions
  • Cost effectiveness
  • Increased safety
  Benefits (other than environmental): medium

Cost effectiveness

Personnel costs take a high share in railway operation and can be dramatically reduced by driverless operation.


A clear requirement for automated rail systems is equal or improved safety compared to conventional operation. An increased overall safety of the system seems achievable as human failure can be minimised.


Train automation can help to increase network capacity through increased punctuality, reduced slot size and moving block systems.

  Barriers: high

Acceptance on the part of drivers

Drivers obviously associate the loss of their jobs with train automation.

Acceptance on the part of passengers

There is widespread unease associated with travelling in a pilotless vehicle. On the other hand, the spreading of driverless people movers and automated metro systems are likely to reduce this scepticism. In the long run, no major acceptance deficits are to be expected, especially if part of the cost savings are transferred to the customer.

Technological hurdles

Whereas automated metro operation does not seem to meet any major technological obstacles, a driverless main line operation still meets many challenges especially as far as safety is concerned. Serious problems arise in mixed operation and due to the fact that there is no physical protection of the tracks (in contrast to underground metro lines).

Transition costs

Although driverless operation strongly reduces running costs, the initial investment into infrastructure and vehicles is high.

    Success factors:
  • Strong R&D emphasis on safety issues
  • External and internal communication on automated train control focusing on improved safety
  Applicability for railway segments: high
    Type of traction:  electric - DC, electric - AC, diesel
    Type of transportation:  passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines, freight


    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: < 5%
  Share of newly purchased stock: < 20%


  Market potential (railways): medium


    Metro line 14 in Paris (operated by RATP)
close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: strongly dependent on specific application
  Energy efficiency potential throughout fleet: strongly dependent on specific application

Automated train operation does not automatically improve energy efficiency. However, an automatic control offers various options for optimising train operation both on a single train level and a systemic level. This includes:

  • Timetable optimisation: synchronisation of braking and acceleration phases of consecutive trains in order to maximise regenerative braking
  • Optimised driving styles: energy efficient speed control and/or coasting
  • Increased traffic fluidity through centralised train control

On the metro line 14 in Paris, RATP has integrated synchronisation of acceleration and braking into the timetable design.

A general quantification of these effects in terms of saved energy is not possible.

  Other environmental impacts: neutral
    (no details available)
close main section Economic criteria
  close sub-section Vehicle - fix costs: medium
    (no details available)
  Vehicle - running costs: significant reduction
    Personnel costs are strongly reduced. Effects of energy savings will be smaller but still economically relevant.
  Infrastructure - fix costs: high
    (no details available)
  Infrastructure - running costs: (no data)
    (no details available)
  Scale effects: medium
    (no details available)
  Amortisation: (no data)


no data available Application outside railway sector (this technology is railway specific)
close main section Overall rating
  close sub-section Overall potential: interesting
  Time horizon: long-term
    First realisations of driverless operation on secured autonomous lines such as metro and people mover systems show principal technical feasibility and customer acceptance of automated train control. Automatic train control as such does not necessarily produce energy efficiency effects. However within the framework of systemic optimisation the potential offered can be substantial. The obstacles for a transfer of such systems to mixed and physically unsecured operation of main lines are very high. From the point of view of energy efficiency, train automation is an interesting approach to the challenges of traffic fluidity, energy efficient driving and regenerative braking. Naturally, this does not tell anything about the general desirability of automated rail traffic.
References / Links:  Hohnecker 1999;  Nau, Carnot 1999
Related projects:
Contact persons:
 date created: 2002-10-09
© UIC - International Union of Railways 2003
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