-  Technologies
  -  Projects
    Contact & Links
    Imprint & Disclaimer

back to list go back to technology list      previous previous technology  next technology  next

   Regenerative braking in freight trains  evaluated  
Due to high average weights of freight trains and the fact that only locomotive axles are powered, high shares of braking power comes from the mechanical brakes in the freight cars, and only a small share is added by the locomotive itself. Based on conventional freight trains, there exists limited potential to raise the share of recovered braking energy.
Technology field: Regenerative braking and energy management
close main section General information
  close sub-section Description

This evaluation refers to the general potential for an increased share of regenerative braking in freight trains. Therefore, many evaluation categories are not applicable as such.

Regenerative braking in freight vs. passenger operation

Compared to passenger stock the potential for regenerative braking in freight trains is very limited. The main reason is the lower ratio of powered to unpowered axles.

  • When comparing to passenger MUs this statement is obvious.
  • But even comparing to loco-hauled passenger trains, freight trains have a disadvantage since they are much longer and heavier and have a larger mass to be braked by unpowered axles.

Limits to braking power of freight locomotives

The braking power of freight locomotives is limited by

  • Adhesion: The maximum force that can be transmitted from the wheel to the rail without slipping (determined by axle load and rail conditions, e.g. on a track with wet leaves adhesion is lower for obvious reasons). Adhesion is difficult to influence.
  • Longitudinal forces: If too much braking force is supplied by the locomotive, the heavy freight cars exert enormous pressure on the braking locomotive which leads to dangerous lateral forces in curves. Therefore maximum permissible longitudinal forces are defined limiting the use of dynamic brakes.

Strategies to increase the share of regenerative braking

  • The most effective way of increasing the share of braking energy recovery in freight service would be increasing the number of driven axles. Based on the present concept of freight operation, this is obviously not realisable. Equipping usual freight cars with a motor for regenerative braking would be unaffordable.
  • The innovative concept of self-propelled freight units would of course change the situation. However, due to the price advantages of diesel engines over electric motors and the operation on unelectrified routes, this concept has better chances to be realised with diesel traction.
  • The introduction of differentiated limit values for longitudinal train forces.
  • Swiss SBB have introduced radio-controlled double-traction in heavy freight trains.
close main section General criteria
  close sub-section Status of development: not applicable
    (no details available)
  Time horizon for broad application: not applicable
    (no details available)
  Expected technological development: not applicable
    (no details available)
  • Energy saving
  • Reduced wear of brakes
  Benefits (other than environmental): medium
    Reduced wear of brakes
  Barriers: high

Regenerative braking in freight trains meets the following limitations and barriers (described in more detail in Description):

    Success factors:

Assessment of status quo

A thorough assessment of status quo is needed for each fleet to identify potential to be exploited without major technological investment.

  Applicability for railway segments: high
    Type of traction:  electric - DC, electric - AC
    Type of transportation:  freight
    (no details available)
    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: not applicable
  Share of newly purchased stock: not applicable
    (no details available)
  Market potential (railways): not applicable
    (no details available)


close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: (no data)
  Energy efficiency potential throughout fleet: (no data)
    Regenerative braking potential in freight trains will be in most cases < 5 % (cf. for example Henning et al. 2000). Data on current share of exploitation of this potential is not available.
  Other environmental impacts: neutral


close main section Economic criteria
  close sub-section Vehicle - fix costs: low
    (no details available)
  Vehicle - running costs: minor reduction
    (no details available)
  Infrastructure - fix costs: none
    (no details available)
  Infrastructure - running costs: unchanged
    (no details available)
  Scale effects: not applicable
    (no details available)
  Amortisation: not applicable
    (no details available)
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: short-term
    Potential for increased use of regenerative braking in freight operation is limited. A thorough assessment of status quo is needed for each fleet to identify potential to be exploited without major technological investment. Possible measures range from a revision of regulations for longitudinal train forces to radio-controlled double-traction.
References / Links:
Related projects:
Contact persons:
 date created: 2002-10-09
© UIC - International Union of Railways 2003
 Your contribution
   add technology
 Views of this page
   show overview
   show evaluation
   show details
 Print options
   print data sheet
   print screen
   Evaluation briefing
   Technology list
    French - German