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   Aluminium car-body  evaluated  
In the last decade aluminium car bodies have replaced steel car bodies to a large extent. This has been a major step towards light and thus more energy efficient rail vehicles.
Technology field: Mass reduction
close main section General information
  close sub-section Description
    Aluminium is substituting steel as a material for railway car bodies in many areas, especially high-speed, main line and regional passenger transport. Most, but not all, modern vehicles have aluminium bodies.
close main section General criteria
  close sub-section Status of development: in use
    Standard technology.
  Time horizon for broad application: now
    (no details available)
  Expected technological development: basically exploited
    According to manufacturers, aluminium car body technology is essentially exploited. A further weight reduction of the car body structure based on aluminium technology is hardly possible.
    Motivation:
    Weight saving
  Benefits (other than environmental): medium
   

Weight reduction

Besides reduced energy consumption, weight reduction leads to

  • higher acceleration rates for given traction power which is especially relevant in high-speed trains
  • less axle load and thus reduced wear of bogies and rail

  Barriers: low
   

Maintenance and repairs

Being the standard technology, aluminium car bodies meet no major barriers in regional and main line stock. In local service, there is still some demand for steel car bodies. Local trains have a comparedly high rate of accidents (minor train crashes etc.) and steel car bodies are easier to repair. Therefore some operators of local networks stick to steel technology.

    Success factors:
    (no details available)
  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
    (no details available)
    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: > 20%
  Share of newly purchased stock: > 50%
    (no details available)
  Market potential (railways): high
    There are still many rail vehicles with steel bodies in service. Therefore, there is still major potential for substitution. Since many manufacturers have invested in expensive equipment for producing of aluminium car bodies, no other technology is expected to conquer the market in the near future. In long-term fibre-reinforced polymers may become a serious competition for aluminium construction.
    Example:
   

 

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 - 2%
   

Compared to steel car bodies, aluminium coaches are substantially lighter. Some experts stress that part of the corresponding energy gain is lost by increased energy demand for comfort functions due to less efficient heat insulation properties of aluminium walls. Although no figures are available, it can be assumed that there is still a considerable energetic net advantage of aluminium over steel.

The mass reduction effect of using aluminium instead of steel for car body construction can be estimated as follows:

The car body accounts for about 20% of the total mass of a conventional MU. It is assumed that replacing steel by aluminium yields a maximum mass reduction potential of about 20-30% of the car body weight. The overall effect on vehicle mass is therefore around 5%. The corresponding overall effect on energy consumption is of about 1 % in main line and about 3 % in local and regional operation (cf. the following elasticity table).

 

Traction

Brake energy recovery

Effect on train mass

Elasticity with regard to train mass

Effect on
total energy consumption for traction

High speed train

electric

no

5 %

0,17

1 %

 

 

yes

0,12

1 %

Intercity train

electric

no

0,19

1 %

 

 

yes

0,14

1 %

 

diesel

-

0,19

1 %

Regional train

electric

no

0,52

3 %

 

 

yes

0,44

2 %

 

diesel

-

0,52

3 %

Suburban train

electric

no

0,64

3 %

 

 

yes

0,57

3 %

 

diesel

-

0,64

3 %

Range:

1 – 3 %

  Other environmental impacts: ambivalent
    An LCA comparison of steel and aluminium cannot be given in a general manner. The overall impact of aluminium depends strongly on recycling rates and production processes. The production of aluminium from bauxite consumes large amounts of electricity and produces the so-called red mud composed of a solution of sodium aluminate and undissolved bauxite residues containing iron, silicon and titanium. The corresponding environmental impact can obviously be reduced by the use of electricity from renewable energy sources (which is the case for some of the aluminium produced in Scandinavia or by high recycling rates. It has to be stressed that given the long life and high utilisation rates of rail vehicles, the positive environmental impact during the use phase plays a much bigger role in the environmental assessment than in the automotive sector.
close main section Economic criteria
  close sub-section Vehicle - fix costs: low
    (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: low
    Due to high costs for manufacturing machinery, scale effects in aluminium technology have been high in the past but are essentially exploited today.
  Amortisation: < 1 year
    (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: very promising
  Time horizon: short-term
    Aluminium offers some substantial advantages over steel in car body technology due to lightweight properties. Today aluminium car bodies are state-of-the-art technology and will probably continue to be in mid-term since manufacturers are interested in amortisation of expensive production facilities. Aluminium technology is very promising for energy efficiency. However, no additional effort is required to facilitate technology diffusion. In long term perspective, aluminium car-bodies will face a growing competition from fibre-reinforced polymers.
References / Links:
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 date created: 2002-10-09
 
 
© UIC - International Union of Railways 2003
 
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