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   Streamlining of train sides and underfloor areas  evaluated  
A great part of the air resistance is due to surface friction along the train sides and roofs, and to the air drag of the underfloor equipment. There is some potential for improvement by streamlining the outer shell, optimising coach transition areas and underskirting.
Technology field: Aerodynamics and friction
close main section General information
  close sub-section Description
   

According to Swedish KTH railway group, in long trains surface friction from sides and roofs accounts for 27,0% of air resistance, the underfloor equipment for an additional 7,5 %. Since these effects are roughly proportional to train length (which is not true for effects from head and tail!), they play a smaller (but still significant) role in short trains.

There is some potential for improvement by

  • streamlining the outer shell
  • finding surface coatings for train sides and roofs that minimise surface friction
  • optimising coach transition areas (which cause major flow separations). ETC recommends that gaps between consecutive coaches should not exceed 250 mm.
  • optimising arrangement of windows, doors and door steps
  • underskirting, i.e. covering the rugged structures of the underfloor surface by a smooth cover.
close main section General criteria
  close sub-section Status of development: in use
    (no details available)
  Time horizon for broad application: not applicable
    (no details available)
  Expected technological development: basically exploited
    (no details available)
    Motivation:
   
  • Energy saving through reduced running resistance
  • Noise reduction
  Benefits (other than environmental): none
    (no details available)
  Barriers: (no data)
    (no details available)
    Success factors:
    (no details available)
  Applicability for railway segments: medium
    Type of traction:  electric - DC, electric - AC, diesel
    Type of transportation:  passenger - main lines, passenger - high speed
    Most of the measures listed in Description, are not suited for retrofit measures but are rather design issues for new stock.
    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)
    Example:
    (no details available)
close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: 2 - 5%
  Energy efficiency potential throughout fleet: < 1%
    According to European Transport Consult, in some high speed trains up to 3 % of the energy consumption could be saved by underskirting alone. However, some of the optimisation potential is of rather theoretical nature and difficult to realize. Therefore, the fleet-wide potential is estimated to be below 1%.
  Other environmental impacts: neutral
    (no details available)
close main section Economic criteria
  close sub-section Vehicle - fix costs: (no data)
    (no details available)
  Vehicle - running costs: significant 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: (no data)
    (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: mid-term
    The theoretical potential for improving the aerodynamics of train sides and underfloor equipment is considerable. However, the possibilities for an implementation of many measures such as a reduction of the gap space between consecutive coaches are rather limited. Feasibility of underskirting seems higher. Some of the measures should be given more emphasis in procurement of new high-speed stock.
References / Links:  Euro Transport Consult 1997
Attachments:
Related projects:
Contact persons:
 date created: 2002-10-09
 
 
© UIC - International Union of Railways 2003
 
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