Technologies        
  Hauptmenu
 
    Introduction
    Database
    -  Technologies
  -  Projects
    Calendar
    Discussions
    Contact & Links
    Imprint & Disclaimer
    Sitemap
 
 


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

   Double-decked stock  evaluated  
Double-decked trains have 20-40% more seating capacity per train length leading to positive impacts on energy efficiency and cost effectiveness.
Technology field: Space utilisation
close main section General information
  close sub-section Description
   

Principle

Double-decked stock can accomodate 20-40% more seats per train length than single-decked stock. Double-decked train design is today a standard solution for many operation types including regional and suburban trains and more recently high-speed trains. Today, mature and well-experienced concepts for double-decked vehicles exist for all classes of passenger operation.

The height over rail is increased to 4600-4700 mm as opposed to less than 4000 mm for conventional stock. The weight increase has to be minimised in order to limit axle load. Therefore double-decked train design is usually combined with strong efforts to reduce weight. For instance, the TGV Duplex has aluminium bodies in contrast to steel construction in single-decked TGVs.

Examples

In suburban and regional transport, double-decked trains have become a standard option in today's railways. The examples for double-decked main line or high-speed stock are more limited:

  • TGV Duplex
  • Shinkansen E1.
  • IC 2000

Infrastructural compatibility

The infrastructure compatibility of double-decked stock is limited but generally higher than for wide-body stock. However, many tunnels pose serious problems.

close main section General criteria
  close sub-section Status of development: in use
   

 

  Time horizon for broad application: now
   

 

  Expected technological development: basically exploited
    Double-decked stock is a mature vehicle concept. Some remaining minor challenges such as pressure tightness on high-speed lines with tunnels, can be solved in short or mid term.
    Motivation:
    Capacity
  Benefits (other than environmental): medium
   

Compared to normal trains:

Since platform lengths in stations are limited (300 m in regional and 400 m in main-line stations), double-decked stock is a means to increase the capacity of a line without increasing train frequency or investing into the construction of longer platforms.

Compared to wide-body trains:

  • Better compatibility with infrastructure
  Barriers: high
   

Passenger comfort

Seating comfort on the seats adjacent to the walls is slightly reduced due to restricted space for legs on the lower deck. This is not problematic in regional or suburban transport where average trips are short. In high-speed trains comfort issues are more relevant and could be an obstacle for double-decked stock. However, existing double-decked high-speed trains in France, Japan and elsewhere are widely accepted by passengers.

Ambulant catering

The staircases pose a problem for a mobile bistro service and for the mobility of passengers in general. In the Swiss IC 2000, a stair-free upper deck has been realized for these reasons.

Boarding times

Due to the stairs the boarding times at stations are increased with double-decked stock. This should be taken into account by operators in the timetable design. For the same reason, mixed operation of double-decked and single-decked stock should be avoided as far as possible.

Technological

  • Pressure-tightness: Double-decked high-speed trains must show a high degree of pressure-tightness. Especially when entering tunnels, pressure waves must not enter the passenger coaches to avoid danger of burst ear-drums. Pressure-tight high-speed stock is still a challenge for manufacturers. Therefore, DB double-deckers may not exceed 160 km/h. TGVs are not confronted with this problem since there are no tunnels in the TGV infrastructure.
  • Tilting is not possible for current double-decked stock

Infrastructure

One of the main obstacles for the introduction of double-decked stock is its incompatibility with parts of the infrastructure, especially tunnels. However, in many regional networks or in flat topography, double-decked stock can be used without any limitations.

    Success factors:
   

 

  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
   

Double-decked solutions exist for all types of passenger trains. Main limitations to its applicability are:

  • incompatibility with infrastructure (tunnels etc.)
  • lines requiring tilting cannot be operated with double-deckers
    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: 5 - 20%
  Share of newly purchased stock: < 20%
   

 

  Market potential (railways): high
   

 

    Example:
   
  • TGV Duplex
  • Shinkansen E1.
  • IC 2000
close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: > 10%
  Energy efficiency potential throughout fleet: > 5%
   

In order to estimate the reduction of seat-specific energy consumption, single-decked and double-decked versions of an otherwise identical train (e.g. equal length etc) are compared.

Aerodynamic effect of higher car body

The cross-section of the train is increased by ~20%. Since air resistance grows with cross-sectional area in a less than proportional way, it is safe to assume that air resistance grows in the order of 10% or less.

Mass effect of higher car body

Double-decked trains are heavier than single-decked trains. The mass increment per train length is of about 10% (e.g. 11% according to a design study by Reemtsema et al. 1997).

Comfort functions

No data are available on the effect on the energy consumption of comfort functions in a double-decked train. For obvious reasons (less wall surface per seat, less interior space to be heated per seat etc), it is increased by less than the relative increase in seating capacity. 10% will be a safe upper limit here as well.

Energy consumption of the entire train

Since all components of energy consumption of a passenger train (mass, air drag and comfort energy) are increased by about 10% or less, the energy consumption will also increase by 10% or less.

Seat-specific energy demand

Since seating capacity is increased by about 20-45%, the 110% energy consumption have to be divided by 1.2 and 1.45 to get the range of seat-specific energy demand relative to a conventional car design. The result is a reduction of seat-specific energy consumption by 8% - 24%.

TGV Duplex

French TGV Duplex can be seen as a benchmark: seating capacity has been increased by 45% as compared to a single-decked train of the same length (e.g. the TVG "Réseau"). SNCF claims that this comes at virtually no increase in energy demand which means that seat-specific energy consumption is reduced by over 30%.

Fleet-wide potential

Assuming that a more than half of the regional and local lines and some of the main lines could be operated with double-decked stock in long term, there is a fleet-wide saving potential of over 5 %.

  Other environmental impacts: neutral
    (no details available)
close main section Economic criteria
  close sub-section Vehicle - fix costs: low
   

The seat-specific investment costs of double-decked stock are highly dependent on the individual features and design of the train. A 100% "ceteris paribus" comparison to single-decked stock is not possible. However, usually seat-specific costs will be lower than for conventional vehicles. In some cases this will not be true, e.g. Reemtsema, Kurz 1997 made the cost estimates on a future double-decked ICE 4 shown in the following table.

Table 1: Initial investment figures for different versions of ICE

 

ICE 4

ICE 4
wide-body

ICE 4
2-decked

Investment 

19.2 million EURO
(100%)

22.0 million EURO
(115%)

25.9 million EURO
(135%)

Seats 

419
(100%)

513
(122%)

506
(121%)

Specific investment per seat

45.900 EURO
(100%)

42.900 EURO
(93%)

51.100 EURO
(111%)

 

Source: Reemtsema, Kurz 1997

Estimates by European Transport Consult confirm that costs are usually in favour of wide-body stock as opposed to double-decked stock.

  Vehicle - running costs: significant reduction
    The seat-specific operation costs are significantly reduced.
  Infrastructure - fix costs: strongly dependent on specific application
    If bottlenecks in the infrastructure have to be removed, costs can be high but heavily depend on the individual case.
  Infrastructure - running costs: unchanged
    (no details available)
  Scale effects: low
    (no details available)
  Amortisation: strongly dependent on specific application
   

 

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
    Double-decked train design is a very attractive option for a variety of application contexts. While double-decked trains have a higher compatibility with infrastructure than wide-body trains, life cycle costs per seta are often in favour of the latter option. Even so, LCC per seat of double-deckers are usually better than in single-decked trains. Energy efficiency effects are very promising. Technological barriers are low and infrastructure problems are usually limited to isolated points of the network. Especially in local and suburban operation, double-decked stock should be used wherever a wide-body design is not feasible. Those operators not using double-decked high-speed trains yet should develop design solutions meeting all comfort and operation requirements together with manufacturers.
References / Links:  Euro Transport Consult 1997;  Reemtsema, Kurz 1997;  Andersson, Berg 1999;  Moreau 1998
Attachments:
Related projects:  New double-decked Regiorunners
Contact persons:
 date created: 2002-10-09
 
 
© UIC - International Union of Railways 2003
 
Aktionmenu
 
 Your contribution
   add technology
 Views of this page
   show overview
   show evaluation
   show details
 Print options
   print data sheet
   print screen
 Help
   Evaluation briefing
   Technology list
    French - German