HSST and Transrapid

Different types of maglev systems have been developed in Japan and Germany. Whereas Japan has developed the High Speed Surface Transport (HSST) system, Germany has developed the Transrapid technology. Both systems coincide by using linear motors for propulsion and electromagnets for levitation. However, the two systems use different types of linear motor. The HSST is driven by linear induction motors with primary coils attached to the train body and the guideway consisting of steel rails and aluminium reaction plates. In contrast, the propulsion of Transrapid trains is realised by a linear synchronous motor. These differences may be explained historically: the Japanese and German systems were planned for different speeds. While the HSST was initially planned for speeds of 300 km/h and present development efforts focus on intra-urban trains running at about 100 km/h, the transrapid developers have been aiming at speeds of 450 to 500 km/h from the beginning.

This evaluation puts a clear focus on transrapid technology, but in great part applies to maglev systems in general.

Technical details of Transrapid

The Transrapid is both propelled and braked by means of a synchronous long-stator linear motor. Ferromagnetic stator packs and three phase stator windings are mounted on both sides along the underside of the guideway. The operation principle can be visualised best by a conventional (rotating) electric motor whose stator is cut open and unwound along the underside of the guideway. Its rotor (excitation) function is taken by the on-board levitation magnets. The vehicle is propelled by an electromagnetic travelling field produced by the longstator linear motor.

The thrust is controlled by means of power electronics on substations along the track. By varying the amplitude and frequency of the AC supply, the vehicle may be accelerated smoothly from standstill to full speed. During deceleration the linear motor becomes a generator (regenerative braking) just as in the case of conventional AC motors.

The vehicles

The planned Transrapid trains are composed of a minimum of two sections, each with about 90 seats. Depending on application and traffic volume, trains may comprise up to ten sections (two end and eight middle sections).

Freight operation

The Transrapid is also discussed as a means for transporting goods. For high-speed freight transport, special cargo cars could be combined with passenger cars or operated as dedicated cargo trains (payload up to 18 tons per section). The propulsion system being integrated in the guideway, the length of the vehicle and the payload do not affect the acceleration power.

Transportation service

• Short travelling time
• High riding comfort

Infrastructure

The track for a maglev system can be constructed more flexibly in topographically difficult areas, since much smaller curve radii (2250 m) are permissible than for conventional railways (3250 m). The reason is that maglev is independent from wheel-rail adhesion and the vehicle encloses the driveway so that there is no danger of derailment.

Incompatibility of infrastructure

The Transrapid being a system technologically incompatible with conventional railway systems, it would need a completely new infrastructure and a step-by-step transition from one system to the other is impossible.

Costs

The high investment costs of infrastructure represent the main obstacle for the implementation of maglev systems.

Lack of in-service experience

The introduction of a new technology is always associated with a number of risks for the operator, especially high uncertainties about the downtime of the system and the maintenance costs.

Acceptance

The controversial discussion in Germany on the (finally abandoned) plan for a Transrapid route from Hamburg to Berlin showed that there is a high level of scepticism about the benefits and worries about the risks of Transrapid systems.

Comparison Transrapid – conventional high-speed trains

A comparison of energy consumption between the ICE and the Transrapid has been the subject of several publications (Mnich et al. (no year), Breimeier 2000, Leitgeb 1998).

There are results from simulation and measurements of power demand for Transrapid. For an unbiased comparison between Transrapid and ICE it is preferable to take energy demand per square meter (of usable interior space) and km rather than energy demand per seat km as a point of reference. The latter perspective would depend on the specific space utilisation of a particular vehicle design and not on the system characteristics. The following figures are therefore based on energy consumption per usable interior area.

Breimeier 2000 gives the following values for ICE and Transrapid for different speeds:

* extrapolated value

Source: Breimeier 2000

The above table shows that above 330 km/h, the Transrapid has an energy advantage over conventional high-speed trains (based on extrapolation).

Due to better acceleration rates, the Transrapid needs less maximum speed in order to achieve the same running time on a given line. As a consequence, comparing running times rather than speeds, the energy comparison will be even more favourable for the Transrapid (at high speeds).

Comparison Transrapid – short-distance air travel and cars

At speeds above 350 km/h that will in the foreseeable future not be reached by conventional high-speed trains, energy efficiency of maglev technology should be compared to airplanes. This comparison yields very strong energy advantages of maglev.

Especially in business travel on medium distances (>300 km), the Transrapid technology could be a serious alternative to cars. It is obviously not possible to make the comparison at equal speeds but even given the speed difference between the two means of transportation, the Transrapid will win over the car (with its low average occupancy) in energy efficiency. This can be demonstrated by the following rough estimate. Assuming a consumption 5-10 liters of fuel per 100 km and an occupancy of 1 person (which is realistic for business travels), one gets a specific consumption of end energy of about 500-1000 Wh/passenger km. At 400 km/h the Transrapid consumes about 60 Wh/ seat – km. If an occupancy of 75% is assumed and an efficiency of the prechain of 25%, this corresponds to about 320 Wh/ passenger km.

It is difficult to compare the running costs of a typical conventional rail system with those of the transrapid mainly because of lacking in-service experience with the latter.

There are some indications that the operation costs (not including the wirte-off of infrastructure and vehicle investment) will be lower:

• The levitation technology reduces material wear and thus reduces maintenance of track and vehicles
• For equal (high) speeds, the energy consumption of the transrapid will be lower than that of conventional high speed systems. For different speeds (e.g. 400 km/h for the Transrapid and 330 km/h for a high-speed rail system), the energy consumption of the transrapid will “only” be about 20% higher.
• The Transrapid is well fitted for an automatic operation which would reduce personnel costs

According to the feasibility study commissioned by the German Federal Government on the “Metrorapid” project for a transrapid from Düsseldorf to Dortmund (79 km), the annual operation costs of the system will amount to about 51 million EUR. This includes costs for energy, personnel, maintenance, insurance, administration etc.