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Learning lessons from tilting trains

01 Apr 2004

DB's failure to meet promised performance improvements where tilting trains were introduced led inevitably to strong media criticism. Murray Hughes finds that many of the difficulties can be blamed on too much innovation pushed through too quickly

PASSENGERS travelling on German Railway's important cross-country corridor between Nürnberg and Dresden are happily riding on tilting trains. Not the ICE-TD tilting diesel trains that DB had promised in 2001, but regional VT612 units painted in the ICE livery of white with a red stripe.

The VT605 tilting ICE-TD sets are mothballed in München, Nürnberg, Hof and Delitzsch while DB ponders their future - it decided at the end of 2003 that they were simply too unreliable to remain in commercial service. Use of the VT612 sets on the route is a compromise intended to recapture lost traffic.

This episode is the latest in a long-running series of unhappy incidents. Trains with active tilt were first considered in Germany in the 1960s, and this led to the purchase of a small fleet of DMUs for regional routes. These had a form of secondary suspension where air was pumped from the bellows on one side of the car to the other as the train passed through curves. The trains entered service in 1972 but technical problems led to work on tilt ceasing in 1975.

The concept was revived in 1987-88, when DB tested the Italian ETR401 Pendolino prototype between Hof, Nürnberg and München. Later that year an agreement was reached with the Land of Bayern to fund a small fleet of VT610 two-car DMUs with Fiat hydraulic tilt to accelerate services on the sinuous routes from Nürnberg to Hof and Bayreuth. At the same time DB was testing Talgo trainsets with passive tilt, which were later introduced successfully on long-distance overnight services.

The 20-strong VT610 fleet entered service in 1992, cutting timings on the 166 km between Nürnberg and Hof from 117min to 86min. The trains attracted much interest from other Länder, and negotiations began for tilt trains to operate several other regional routes.

The immediate success of the VT610s did not come without a price. Considerable work had been undertaken to upgrade the routes, paid for by the Land, allowing line speeds to be increased to a maximum of 160 km/h in favourable locations. It was the combination of faster running generally and tilting that helped the VT610s to generate a 23% increase in traffic in the first year.

Disastrous debut

For the next build of tilting DMUs, an alternative to the Italian tilting equipment was sought. German suppliers AEG and MAN offered an electrically-actuated option based on equipment used to keep the guns of tanks level while traversing uneven terrain. This was chosen for 50 VT611 tilting DMUs, which were ordered from Adtranz in August 1994 for use in Baden-Württemberg and Rheinland-Pfalz, which helped to pay for them. The order included an option for 50 more.

The first VT611 units entered service in September 1997, on routes from Frankfurt to Heilbronn and Saarbrücken. Disaster struck immediately, and by mid-October DB had withdrawn the entire fleet for modifications. Problems were reported with doors, air-conditioning, drive shafts, oil valves in the diesel engines and magnetic rail brakes. The electronic tilt controls also malfunctioned, particularly during multiple-unit operation.

Why the problems? According to Dipl-Ing Hans-Peter Lang of DB Systemtechnik in Minden, there were simply too many items of unproven equipment on a single train. Apart from the tilt equipment, the bogies featured radial steering, while the doors, air-conditioning, couplers and other items were all newly-developed. The tilting equipment functioned satisfactorily, he said, and it did not cause major problems. There were certainly no design problems in the tilting equipment, he affirmed, although there were 'issues with manufacturing quality' of some components.

The fundamental problem, he believes, was the extraordinarily tight timetable for designing, building and commissioning the VT611 fleet. Just two years was allowed between the placing of the order and the start of commercial service. 'The suppliers should have said "give us another six months", but they lacked the courage', remarks Lang. Ideally, there should have been a component test train, and a VT610 was in fact fitted with parts of a VT611 bogie, but by that time the first VT611s were already rolling off the production line. In the end, some units were put through just three or four days of trials before they were pressed into service.

DB was unable to maintain the faster timings with its replacement trains, and this upset many passengers, leading to more bad publicity. The Länder were particularly disappointed, and made no secret of their discontent. The upshot was withdrawal of the VT611s for a rolling programme of rebuilding at what Lang describes as a 'brutal' cost to the supplier.

DB was very concerned about the bad image its tilting trains were getting, but it remained convinced that its strategy for accelerating services on regional routes was correct. In August 1998 DB went ahead with an order from Adtranz for 154 VT612 units that were derivatives of the VT611. The first of these was demonstrated at the InnoTrans show in Berlin in November 1998. Later orders took the total of VT612 units to 192.

The VT612 fleet has also suffered problems, but DB is content that they now provide satisfactory standards of service and reliability on numerous routes. Thanks to tilt, DB has in many cases been able to cut journey times without resorting to expensive upgrading work.

Long-distance routes

DB now operates tilting trains over no less than 2200 route-km of regional lines. A further 1800 route-km are served by long-distance tilting trains, and DB plans to add another 500 route-km by 2008.

DB's fleet of electric tilting trains for long-distance routes consists of 32 seven-car ET411 and 11 five-car ET415 trainsets. Another 28 ET411 units, all formed of seven cars, are on order, and the first of these has been on trial at Siemens' Wegberg-Wildenrath test centre since early January. The first will be delivered in the middle of this year and should enter service in December. The trains are virtually identical to the earlier build, as DB wants to ensure that components will be interchangeable.

Dipl-Ing Klaus-Albert Bolten, responsible for long-distance tilting trains at DB Systemtechnik, notes that DB first considered tilting trains on its inter-city routes in the 1990s. With no prospect of building new lines outside the busiest corridors, the objective was to develop faster trains that offered the same level of comfort as the ICE fleet to replace loco-hauled stock.

The initial order for ICE-T trainsets able to run at 230 km/h was placed in 1994 with a consortium grouping Siemens, Fiat and DWA. The trains were to receive the second-generation Fiat hydraulic tilting system as fitted to Italian Railways' ETR460 Pendolino sets. Again, the timescale for design and production of the trains was ambitious, and it was not until May 30 1999 that the first ICE-T entered service between Stuttgart and Zürich in Switzerland.

The trains were also destined for the important 700 km route between München, Nürnberg, Leipzig and Berlin, where plans to build sections of new line were delayed by political issues and high costs. Several sections of this route were in need of upgrading, and temporary speed restrictions often prevented the ICE-T units from keeping to their published timings. There were also problems with the quality of various components, and all this served once again to upset customers and generate more negative publicity.

Meanwhile, DB was changing its business philosophy, and it sought increasingly to transfer responsibility for the performance of its trains to the suppliers. Trains were now purchased on the basis of a performance specification, and the requirement was for no more than 10 faults per million train-km, with a fault defined as a delay of more than 5min or a tilt failure. Typically, an ICE-T is diagrammed to run 400000 km a year, similar to other ICE trainsets. Once a programme of modifications has been completed, DB expects that by the end of 2004 the ICE-T fleet will be meeting its specified requirements.

More trouble arose when there were two low-speed derailments of ICE-T sets in Berlin. The problem was quickly traced to the failure of a valve mechanism in the hydraulic tilt apparatus. Bolten says this was a known fault identified by the supplier and that the trains were already undergoing a programme of modifications to rectify the problem. Unfortunately, the trains concerned had not been modified.

Despite all this, the second series of ICE-T trains now being delivered confirms DB's satisfaction with the design. Suppliers are Siemens, Bombardier and Alstom, which is providing the bogies and tilting equipment following its takeover of Fiat Ferroviaria.

Diesel tribulations

While preliminary options were being assessed for the ICE-T fleet, DB was working in parallel on its initial design for the ICE3. This represented a major design change, with a switch from separate power cars to distributed power using traction equipment in several cars along the train. The ICE-T development programme was in fact running a few months ahead of the ICE3, and the ICE-T was DB's first high speed train with distributed power since three ET403 prototypes were built in the 1970s.

A few important long-distance routes remain unelectrified, and for these DB decided to develop a diesel train meeting ICE standards. One option was a long-distance version of the diesel-hydraulic VT612. The alternative offer from Siemens and Bombardier was for a four-car diesel-electric trainset similar to the ICE3, with 8í tilt. Underfloor engines would drive traction motors mounted in the bogies. The electric tilting system was also to be mounted in the bogie, leaving space under the floor for the 1000 litre fuel tank required to give the trains an operating range of 2000 km. Lang points out that Siemens had had no previous experience with developing its own active tilt equipment.

Contrast this design proposal with the proven ICE-T units, where body-mounted traction motors drive the axles through cardan shafts. In favour of the Siemens design was the use of identical or near-identical mechanical parts, excluding the bogies, and the same fittings and interiors as the ICE-T and ICE3 trainsets. In the end DB picked the Siemens design for a fleet of 20 VT605s. Bolten acknowledges that the development and construction timescale was short, and admits that 'it was not an easy job'. With the trains designed to run at 200 km/h, the new bogie design was tested up to 275 km/h under a VT610 trainset.

The trains were intended to lift service standards on the Nürnberg - Dresden route. Serving the southern part of the former East Germany, this line was politically important, and DB promised ICE comfort and shorter journey times in a major publicity campaign. Expectations built up, and when the trains were launched in 2002 after a year's delay, passengers flocked to use them.

DB Netz, responsible for infrastructure, had been tardy in pushing through upgrading plans, and work was still going on when the trains finally entered service. Inevitably, this led to delays.

But worse was to come. The VT605s were attractive and passengers were thrilled to ride them. But the high expectations changed swiftly to anger and disappointment when the trains failed to meet DB's requirements for reliability and performance. According to Bolten, the underfloor engines were 'rougher' than anticipated. But the main issue was 'a fault diagnosis system that was too sensitive, often tripping out and causing the train to fail when there was no real problem'. The electric tilt actuation system was also felt to be 'very complicated'.

DB set up working groups with its suppliers to address the problems, but according to Bolten solving one difficulty would often trigger another. Numerous software changes were made, but the trains were still problematic. In an unrelated incident, one train was damaged beyond repair after falling off its lifting jacks in the workshop at Hof.

In December 2002 a VT605 unit derailed after breaking an axle at Gutenfürst, fortunately without casualties. This prompted an instruction from the Federal Railway Office (EBA) that the trains could only operate with the tilt switched out to reduce the forces exerted on the axles. However, Siemens was able to resolve the problem and instigated a modification programme that led to the EBA recertifying the trains for use with the tilt active.

Meanwhile 'the market had collapsed', with passengers deserting the trains after two years of unsatisfactory service. At the end of last year the DB board decided that enough was enough. The trains were withdrawn and replaced by a batch of 17 VT612 two-car units modified to accept seat reservations and provide a minimum level of catering. DB comments that 'we promised the customer to cut journey times, and that is now our highest priority'. Early indications are that this strategy is working, but Bolten is clear about one thing. 'We have learnt our lesson, and we will not allow this to happen again'.

 

  • CAPTION: DB uses this VT612 test train to check that infrastructure is suitable for tilting train operation, as shown here between Chemnitz and Klingenberg-Colmnitz Photo:DBAG/Busse
  • CAPTION: VT612 trainsets in the white and red long-distance livery have been pressed into service to replace the mothballed VT605 fleet between Nürnberg and Dresden Photo:DBAG/Busse
  • CAPTION: DB runs tilting trains on routes that total around 4000 km, and another 500 km is due to be added by 2008
  • CAPTION: An ET415 at München - DB expects these
  • ICE-T sets to meet specified performance criteria by the end of this year; a further 28 sets are on order Photo:Artemis Klonos
  • CAPTION: After extensive modifications, the VT611 fleet is back in service on regional routes such as Basel - Lindau Photo:DBAG/Klee
  • CAPTION: The future of the VT605 fleet remains unknown following their withdrawal at the end of 2003 Photo:Artemis Klonos

Fleet could be 'up and running'

On October 22 2003 Siemens issued a statement about the VT605 tilting diesel sets saying that 'the withdrawal of the ICE-TD from the ... line between Nürnberg and Dresden notified on Monday October 20 2003 is not the result of technical problems with the rolling stock. The Siemens-Bombardier consortium will, as agreed with DB, continue the ongoing work on the wheelset journals and make certain that the ICE-TD is ready for service when the new timetable comes into force on December 14 2003. So far 16 of the 19 trains have been re-equipped.'

It also said that the wheelset journals 'were manufactured according to the latest state of the art. All relevant standards and guidelines were complied with. The material was examined and found to be good. The manufacturing consortium can consequently not be accused of any errors in design.'

The statement also noted that 'the diesel-powered tilting ICE commenced scheduled service in June 2001. Certain technical problems arose in operation. Appropriate action was taken to stabilise fleet service; a technical availability level of more than 98% was attained over a period of months. Services have been subject to certain restrictions since December 2002 following a wheelset journal break, whereafter the trains ran initially without tilting (as a precautionary measure) and were even for a short time out of action.' On December 8 another statement from Siemens confirmed that all the fleet had been modified and that the planned journey time reductions on the Nürnberg - Dresden route 'would be possible with the ICE-TD'.

Siemens said last month that it 'respected DB's decision to withdraw the ICE-TD fleet', but added that the trains 'could be up and running'.

Apprendre les leçons du pendulaire

Le chemin de fer allemand a souffert d'une mauvaise publicité centrée sur les problèmes liés à son important parc de matériel pendulaire. Murray Hughes trouve que beaucoup de ces difficultés sont dues à une trop grande quantité d'innovations appliquées trop rapidement sur les parcs d'automotrices diesels VT611 et VT612 de la DB, construites pour les services régionaux, mais qui offrent désormais des niveaux acceptables de fiabilité. La DB prend maintenant livraison de sa deuxième série de rames ICE-T, mais les ICE pendulaires diesels VT605 restent dans leur cocon pour le moment

Was aus Neigezügen zu lernen ist

Viele Kunden der Deutsche Bahn waren durch die Probleme der Neigezug-Flotte enttäuscht, und die DB hat stark unter schlechter Publizität gelitten. Murray Hughes stellt fest, dass viele der Schwierigkeiten auf zuviel Innovation, während zu kurzer Zeit eingeführt, zurückzuführen sind, wobei die Dieseltriebzüge der Baureihen 611 und 612 für den Regionalverkehr nun akzeptable Zuverlässigkeit erreichen. Die DB übernimmt nun die zweite Serie an ICE-T-Zügen, aber die dieselgetriebenen ICE-Züge der Baureihe 605 werden wohl für immer eingemottet bleiben

Aprender la lección de los trenes pendulares

Los Ferrocarriles alemanes han sufrido una mala publicidad que gira en torno a los problemas sufridos con su amplio parque de trenes pendulares. Murray Hughes ha descubierto que muchas de las dificultades pueden achacarse a una excesiva innovación aprobada demasiado de prisa, con el parque de la DB de trenes diesel VT611 y VT612 fabricados para los servicios regionales ofreciendo en estos momentos unos niveles aceptables de fiabilidad. La DB est? recibiendo la segunda serie de trenes ICE-T pero por el momento las unidades ICE pendulares diesel VT605 permanecer? n fuera de servicio