Super Voyager completes tilt trials in France
A Virgin Trains Class 221 tilting trainset was put through a stiff programme of trials on SNCF's corkscrew line between Brive and Cahors. Murray Hughes reports from the test site
STAFF and passengers on French National Railways' line between Brive and Cahors in the Lot département grew accustomed to the strange sound and sight of a British visitor during January. Staff at Souillac, for example, quickly learned that le klaxon anglais heralded the appearance of the striking red and yellow nose of a Virgin Trains Super Voyager trainset. The Class 221 unit had been sent to this sinuous section of the Paris - Toulouse main line for body tilting trials, not least because it boasts 130 curves in just 101 km. The sharpest of these has a radius of just 370m.
The numerous curves limit line speed between Brive and Cahors to 110 km/h, which is one reason why the Paris - Toulouse route has been selected as the first in France to be worked by TGVs converted for tilt operation, probably from 2005. SNCF faces tough competition from a new motorway that has recently opened to a point near Cahors, as well as from internal air services.
The Class 221's final tilting test run was made on February 1, when Virgin Trains and builder Bombardier Transportation staged a demonstration trip before the train moved north for a series of high speed trials between Le Mans and Nantes. The occasion was also used to familiarise a party of Virgin CrossCountry drivers with the train's tilting ability, and Secretary of the CrossCountry Drivers' Company Council Jeff Towner named the test unit Louis Bleriot in a ceremony at Cahors.
The four-car trainset was the first of 44 units off the Bombardier production line at Brugge, and during October last year it underwent running trials in Belgium with the tilt system inoperative. An initial series of high speed tests was then staged between Le Mans and Nantes in December before the train moved to the Brive - Cahors route, where it was authorised to run at 130 km/h during a programme of trials starting on January 7.
'A calm train'
Commenting at the end of the demonstration run on February 1, Virgin Trains' Chief Executive Chris Green described the Class 221 as 'a calm train', in which you only notice the tilt 'when you are with the driver and see how much faster you are going than other trains'. For passengers, he said, 'it's a non-event', with the tilt system 'exceeding expectations'. He said that SNCF had provided 'the ultimate test track for tilting train', suggesting that the Paris - Toulouse line's 'corkscrew route' made Britain's West Coast 'look like a straight line'.
The test programme had been arranged by Eurailtest, a joint venture set up three years ago by SNCF and Paris transport operator RATP; SNCF has a 90% stake. Eurailtest works mainly on French projects but has been involved with testing of the Korean TGV trainsets and Amtrak's Acela Express units in the USA. For Class 221, the firm is working in partnership with Serco of the UK.
Eurailtest is handling the organisation of trials in France, where it has been contracted to carry out a range of measurements that include lateral and vertical forces exerted on the track during tilting. The company is also involved with dynamic measurements in Britain, where Railtrack is making available an instrumented test section. Serco arranged the British trials and has had some involvement with braking trials in France.
The hydraulic tilting system originates from that used on Canada's LRC train in the 1970s. The design was developed further for Amtrak's Acela Express, and this in turn was chosen as the basis for the Super Voyager's tilting mechanism. To allow development work locally, Bombardier acquired two former gas turbine RTG power cars from SNCF to form its Axis test train and fitted them with tilting equipment.
Several improvements have been made compared with Acela Express, according to Mark Breemersch, Head of the Eurotilt department at Bombardier Transportation's Crespin plant, where bogies for all the Super Voyagers are being built.
The biggest advance, said Breemersch, is to reduce the time lag between detection of a curve and activation of the tilt mechanism, particularly on the leading car. This has been achieved by incorporating a processor with the gyroscopes and sensors on the leading bogie, to calculate the required angle of tilt.
This saves the time needed to send the sensors' measurements to a processor elsewhere on the car, and the message instructing the tilt actuators is sent directly from the lead bogie to calculate the required angle of tilt. This means that tilting on the leading car 'is practically in real time', said Breemersch.
The tilt actuation module on the Super Voyager is more compact than on the Acela Express, with the oil pump and reservoir located in a single unit mounted below the floor.
Should the tilt equipment fail on one or more cars, the bodies are automatically returned to the centre line with zero tilt on the whole unit. Cars on a second trainset running in multiple are also centred if there is a tilt failure. The train may then remain in service with the tilt locked out of use. Bombardier has subcontracted maintenance of the tilting equipment to the Canadian company Hydrofab.
The train is due to arrive in the UK in time for tilt tests on the Carlisle - Carnforth section of the West Coast Main Line in April, by when Tilt Activation & Speed Supervision equipment should be installed on the route (RG 5.00 p313). Trials will also be carried out to check the operation of the tilting system between Banbury and Oxford in July, and this route should be cleared for commercial operation with tilt activated by October. Non-tilting trials with a Class 221 have already been made on the East Coast Main Line at up to 200 km/h.
Virgin expected to obtain a safety case for non-tilting commercial operation last month, with a full safety case for running with tilt activated due in June. The trains will operate initially with the tilt inoperative, and then in tilting mode at existing line speeds. Only in May 2003 will the tilt be used to take advantage of higher curving speeds than other trains.
Class 221 will be used primarily on VCC services that run over the West Coast Main Line north of Birmingham. These include Plymouth to Blackpool and Glasgow, Poole and Portsmouth to Edinburgh, and Brighton to Liverpool and Manchester.
A four-car Super Voyager is 40 tonnes heavier than its 34 non-tilting Voyager sisters, much of the additional weight being in the bogie which is of a different design to accommodate the tilt equipment. The two builds are otherwise identical, with components from the same suppliers (Table I).
Table I. Main suppliers for Virgin Class 221 Super Voyager DEMUs
|Main contractor||Bombardier Transportation|
|Training simulators||Oktal Technirail|
|Passenger information and entertainment||Televid|
Drivers trained on simulators
Drivers are being trained to operate the Voyager and Super Voyager DEMUs at Virgin's Crewe training centre, which opened in October 2000 (RG 5.01 p353). Two full-motion simulators with widescreen graphic displays were supplied by Oktal Technirail of France to replicate the cabs of the two classes. The principal difference on the Class 221 is the TASS module that controls the tilt. The Train Management System is fully functional, with extra facilities to teach drivers to cope with faults which would require them to leave the cab.
- CAPTION: Class 221 tilts at up to 6°. During trials the specification of 225mm of cant deficiency was exceeded up to a maximum of 270mm
- CAPTION: Instrumented wheelsets (above) were used to measure dynamic forces
- CAPTION: Virgin Trains' Chief Executive Chris Green described the Class 221 as 'a calm train'