High-speed rail vehicles: State of the art and further developments

Kurzfassung

Worldwide a lot of high speed railways are successfully operating. Until the 1970s, the market share of the European railways in passenger transport decreased strongly due to the fierce competition of individual motor car traffic and of civil aeronautics. The development of high-speed trains and the construction of new high-speed lines, which started in Europe at the end of the 1960s, helped the railway companies a lot to regain lost market shares based on the developments in Japan, France, Italy and Germany. Currently, high-speed trains provide a short and comfortable travelling at maximum operating speeds up to 380 km/h: New lines are planned or built in many countries. Major developing goals for future high speed trains are focused on higher acceptance by offering higher travelling speeds, improved passenger comfort and a high level of safety as well as on better economic efficiency by a reduced energy consumption per seat and lower life cycle costs. The challenge is especially the goal conflict between the increasing of the speed and the reduction of the energy consumption, because the air resistance is proportional to the square of the speed. For instance, the German ICE 3 high-speed train needs a traction power of 7500 kW for travelling with constant speed of 330 km/h on an even and straight track. More than 90% of this power is needed for negotiation of the air resistance. Therefore the optimisation of the aerodynamic design is one of the key issues for an environment friendly train. The internal DLR research project “Next Generation Train“ (NGT) represents a lot of innovative developments. Nine DLR institutes are engaged in different rail specific topics such as aerodynamics, structural design, energy systems, new materials, passenger comfort, running dynamics and vehicle concepts. The most important target of this project is an energy reduction per seat of 50 % compared to the ICE 3. However, the potential of energy reduction by aerodynamic optimisation is not sufficient for this target. Therefore, the concept of the NGT consists of a high speed double-deck trainset in order to obtain a higher increasing of the capacity (i.e. number of seats) than of the air resistance. The passenger comfort of a double-deck train can be significantly increased by continuous floors on both levels. However, the arrangement of two decks for passengers above a conventional running gear would exceed the admissible height given by the European loading gauge. Therefore, the operation of such a train is impossible in Europe. This requires a novel concept for the running gears to avoid this problem. The axle shaft connecting both wheels of a conventional wheelset is an essential element which enables a passive control system for the running dynamics. Since the wheels need a certain minimum diameter of about 1 m, the space for the axle is no longer available in a double-deck train with continuous floors. Therefore, the mechanical component of the axle is replaced by a mechatronic system. In addition, this mechatronic system offers further benefits by improving the running dynamics and the wear behaviour of the running gears. This example demonstrates how an innovative running gear concept can contribute to an integrated and environment friendly train concept.