Infrastructure compatibility

On some of the tracks presently not allowing wide-body stock, infrastructural compatibility could be reached by various technological measures concerning the stock rather than the track:

• by ensuring an increased stability of the coach body against lateral swaying in narrow parts of the track.
• by an active suspension reducing the lateral spring travel and thus allowing a further 50 - 70 mm of car-body width within the same car-body dynamic envelope.
• and by some further down the road concepts as e.g. by laterally displacing the coach body by 3 or 4 cm with respect to the running gear in order to avoid infrastructural obstacles or by tilting the coach body away from infrastructural obstacles. The implementation of such measures would require an advanced level of train control and seems unlikely in the foreseeable future.

Further, it is highly desirable to develop standardised advanced methods for vehicle gauging, based on simulations, thus making it possible to fully utilise the available structural gauge.

Comfort

More research and development is needed to better understand the relations between used space, experienced space, ergonomic factors and passenger’s positive / negative feelings, as well as their willingness-to-pay. It is also desirable to develop trains with even higher comfort in the long term. It is then favourable to increase interior width to at least 3.3 m. In such a case it is important to introduce new wall designs with reduced thickness (and maintained strength).

Capacity

Capacity considerations are the main motivation for using wide-body stock: Capacity expressed as number of seats per hour is essentially proportional to the number of seats per train metre. This means that wide-body stock increases capacity by around 20%.

Compared to normal trains:

• Capacity: Increased capacity of a line. Increased platform capacity.
• Night train comfort: The wide body is a prerequisite to design a comfortable night compartment with two beds along the side-wall.

Compared to double-decked trains:

• Equipment: In wide-bodies most of the equipment can be accommodated in the available underfloor space of the passenger car, typically 30 – 35 m³.
• Tilting: lower centre of gravity, possible car-body tilt and higher curving speeds,
• Catering: level floor within the train making it possible to arrange ambulant catering service
• Simplicity: simpler interior construction.

Infrastructure

The main obstacle for the introduction of wide-body stock lies in the infrastructure, which is not adapted to wide-body stock for historical reasons. For certain isolated networks (mainly suburban lines) and some regional and long distance lines wide-body stock could be introduced without major infrastructural changes. The demand for interoperability in intercity and high speed traffic limits the allowed stock width considerably. This can be exemplified by the ICE family: Whereas the ICE 1 and ICE 2 had a width slightly over 3000 mm, the ICE 3 facing greater requirements of interoperability has been constructed to 2900 mm only.

From the view of manufacturers a great obstacle is given by the paradigm of many operators to accept only stock that can in principle be used throughout the network. This impedes insular solutions for regional networks allowing wide-body stock.

Passenger acceptance of 2 3-arrangement

A 2 3 seating solution may result in a certain reduction of passenger comfort. Especially the middle seat of the 3-seat-arrangement may be considered uncomfortable and not be readily accepted by passengers. However this effect is over-estimated as various surveys in Sweden showed. The passengers were asked for their preferences expressed as willingness-to-pay for more comfort. Even the most negative result was only slightly negative corresponding to 2 % of ticket price for a 2 2- instead of a 2 3-arrangement.

Assessment of potential for insular solutions

An unbiased assessment of the operability of wide-body stock on parts of the infrastructure will mostly reveal major potential in local and regional operation. If a small number of obstacles has to be removed, a cost-benefit analysis has to evaluate the profitability of such a transition.

Critical revision of the paradigm of “regional interoperability”

Many railway operators only purchase stock with a high degree of applicability throughout their infrastructure. For example, DB AG wants a regional train used in Bavaria to be usable in other parts of the country as well. This obviously limits the potential for wide-body stock. A critical revision of this “regional interoperability” paradigm is needed to assess whether it is economically reasonable.

Only passenger trains.

High potential in isolated networks, such as suburban and some regional lines.

On main lines, potential may be much greater than commonly assumed:

In 1990 DB, DSB and NS concluded that stock of a max. width of 3200 mm at around 1600 mm above rail level and of normal width at platform and roof level could in principle be accomodated on these three systems.

A Swedish study concluded that it would be possible to accommodate a car-body width of 3.4 -3.5 m at “elbow height”, within the present structural gauges in Sweden and Norway, likely also in Denmark.

Studies by DB AG indicate that the main part of the ICE network with the exception of very few bottlenecks can be worked by trains 3.40 m wide. Concepts excluding narrow sections could be feasible in mid-term perspective on the major network axes.

Research by Swedish KTH showed that wide-body trains can be used on many markets, not only high-speed, InterRegio, local and regional trains but also for day-and-night trains. To make night-trains profitable in the future it is necessary to design trains that can be used both in night-service and in day-service.

Copenhagen urban trains

For the new S-trains needed for the Copenhagen suburban line, a Siemens / LHB consortium developed in close co-operation with DSB a train especially adapted to the local situation. The invitation to tender already contained a number of environmental requirements to be met by the manufacturer, among them a considerably reduced energy consumption.

In order to increase seats per train length and reduce energy consumption per seat, the car-body was extended to the outer limits allowed by track profile and station platforms. A car-body width of 3.60 m proved feasible (0.58 m more than the old stock). This allowed three seats on both sides of the aisle (old: 2 on one side, 3 on the other) and 336 seats per train set (old: 260 seats per train set) without changing train length. This along with a number of other measures (one-axle-bogies etc.) reduced weight per seat by 34 % to 357 kg. Compared to previously used stock, energy consumption was reduced by 60 % (!).

According to DSB, acceptance of the new trains is high both on the part of DSB personnel and of passengers.

Although a direct transferability of this particular train to other networks is doubtful, since the train was developed especially for the Copenhagen track profile and station platforms, the case can be seen as a positive example of how to implement a train solution in an isolated network that both optimally meets the requirements of the operator and energy efficiency.