|Light Rail Transit Association
Light Rail for better public transport
Michael Taplin discusses the merits of the guided bus. Despite many years of debate, they have so far made little impact on the street scene.
We all know the guided bus has been around a long time. Geoffrey Skelsey and Roger Jones first wrote about them in Modern Tramway in September 1986 (almost coinciding with British bus deregulation, which saw off the only example then in use in the UK). At that time Essen (Germany) with 9 km, Adelaide (Australia) with 12 km and Birmingham (UK) with 0.5 km were using the O-Bahn system developed by Daimler Benz, and later christened by James Freeman of Badgerline KGB, or kerb-guided bus. This made the ‘control mechanism’ easier to visualise in an era when a lot of other initials started to be bandied about to label innovative transit systems. Essentially horizontal guide wheels fitted to the front axle of a bus guide it between vertical kerbs.
The KGB subsequently disappeared in Birmingham, but a short section (0.4 km) was laid in the German city of Mannheim to bring buses along a tramway reservation in order to provide priority at traffic lights. In the UK Leeds took up the idea and after trials using ex-Birmingham parts, succeeded in attracting Government funding for installations in two corridors. A short section (0.2 km) was also installed in Ipswich as part of what today would be called a Bus Quality Partnership.
An obvious disadvantage of the KGB is that it creates a physical barrier along the route, and cannot be used therefore for street running. It also involved diesel buses, which rather spoilt its environmental credentials (at least until EURO2 engines and low-sulphur diesel came along), though Essen did put trolley poles on theirs for a while to create a guided trolleybus. Two poles were needed because there could be no current return via wheels and rails as with a tramway. Anyway, after 15 years the only place in the world still building KGB is Leeds.
Meanwhile a stranger device emerged from the factory of La Brugeoise (BN) in Brugge, Belgium, to be demonstrated initially on a short track in the shadow of the Atomium in Brussel. This was labeled GLT (Guided Light Transit) and was a rubber-tyred vehicle but with a pantograph on its roof, feeding power to electric motors to provide the drive. As well as a steering wheel, at the centre point of the underside of the vehicle a pair of in-line small double-flanged wheels were held down onto a centre slot rail by hydraulic force. When running under electric power from a single overhead wire these wheels also acted as the current return. An auxiliary diesel motor was fitted to provide power to the electric motors when running away from the guideway and overhead. A longer section of test track was built along some 4 km of disused railway between Jemelle and Rochefort in the Ardennes, and two quite smart prototypes carried out extensive trials, including public operation, in the early 1990s. A third prototype was given bogies and ran trials as a tram in Bruxelles, but these high-floor vehicles were soon rendered obsolete by the arrival of low-floor trams (and later buses). Another significant problem was excessive noise caused by the oscillation of the wheel in the guideway.
BN was by now part of Bombardier and quite an aggressive campaign was waged to sell the system as an intermediate mode between tram and bus, with all the kudos of the former at only half the cost. The aforementioned James Freeman was responsible for bringing one of the prototypes to Bristol under Badgerline auspices, seeing an opportunity to take advantage of the political and financial woes then affecting the ATA light rail scheme. Nothing happened in the UK, but in France the Bombardier salesmen were able to tap into the desire of any French city worth its salt (with Government encouragement) to have its TCSP (Transport en Commune en Site Propre) or segregated surface transit system. Most went for trams of course, but it was inevitable that some politicians were going to jump at the opportunity to have a ‘half-price tramway’. And it was in the city of Caen that this happened.
The Bombardier vehicle for Nancy at the Crespin factory away from its guidance rail, and before mounting of the trolley poles. The 24.5-m long, 2.5-m wide vehicle weighs 25.5 t, about 20% more than an equivalent bus. (Bombardier)
It was in 1994 that Caen decided to nominate Bombardier to build a GLT line, a decision no doubt helped by the company’s decision to manufacture the vehicles at the French factory of ANF Industrie at Crespin, now part of the group. Suddenly the GLT was a French product (and redesignated TVR Transport sur Voie Reservé). The intention to have the system built in 1996-8 was thwarted by local politics and legal challenges following a referendum which seemed to show the majority of local people were against the idea. Construction of the 15.7-km wholly-guided line finally started in March 2000, with public service scheduled for September 2002. The cost, including 24 Bombardier vehicles, is predicted to be FRF 1300 million.
Translohr is a very stylish vehicle that matches the low-floor tram in ambience. It is seen here on a 10.5-m radius curve at the Lohr test track. (F. Muth)
This delay in gaining approval for the Caen line permitted Nancy to come up on the ‘inside rail’ and achieve the first TVR in revenue service. Nancy, a city of 255 000 in the eastern Lorraine region of France built a completely new three-route 30-km trolleybus system in 1982/3, using 50 Renault articulated trolleybuses with diesel generators which permitted operation ‘beyond the wires’. By 1998 the vehicles were becoming unreliable, with spares hard to obtain, and when the Bombardier salesmen came calling the opportunity was seen to preserve the investment in the system infrastructure while upgrading to tram-like performance by choosing a guided trolleybus system, using TVR guidance for the central portion. An 11-km line (8.6-km guided) has been built at a cost of FRF 978 million, including 25 Bombardier vehicles for FRF 274 million. As is often the case in France the target was set to have the line running before the next municipal elections on 11 March 2001.
Lyon managed to build its 18.3-km tramway to a similar timescale, but Nancy had to cope with unfamiliar infrastructure and the first production batch of a unique type of vehicle. The planned dates in December 2000 and January 2001 passed in a flurry of teething troubles and it was not until 11 February 2001 that squadron revenue service started. The ‘tram on tyres’ became an election issue, with allegations that the vehicles did not meet safety criteria, and complaints about the noise generated by their operation. Worse was to come, for on 6 March at the point where the route transforms from guided to unguided mode (Essey) a vehicle lost stability with the rear end striking a traction pole, and three passengers injured by flying glass. The drivers then went on a one-day strike on the grounds that the new system was unsafe. Persuaded back to work, exactly the same thing happened at the same point on 10 March, fortunately at 05.50 in the morning, so there were no injuries. The line was shut down immediately and indefinitely pending the inquiry to be held by a technical commission.
At least one of our members had in fact witnessed a similar incident on the TVR test running in Paris (a guide rail was installed on 1.5 km of the 12-km Trans Val-du-Marne busway) in spring 2000, describing the rear end as behaving like a scorpion’s tail, with only good luck preventing contact with anything solid. That incident never hit the headlines (and may have been hushed up), but it now seems clear that there is an inherent instability to the rear section of a TVR vehicle, which is triggered by a particular set of circumstances. The Bombardier engineers must be worried people.
Which brings us to the title of this article, for no sooner does one type of guided bus leave the stop, than another one seems to appear, chasing the holy grail of the ‘tramway effect’ for the cost of a bus. Readers of our news columns will have already noticed the decision of Rouen and Clermont Ferrand to chose the Civis system developed by Renault-Matra. Rouen wanted something to scale its eastern heights (where gradients were too steep for an extension of its new tramway system), while Clermont Ferrand was the home of Michelin tyres, and anxious to have a rubber-tyred vehicle on its TCSP. Civis is an optical guidance system with a dashboard-mounted camera tracking a double dotted white line on the road surface through the windscreen, and passing electronic guidance commands to the steering. The vehicle (Renault has become part of Irisbus) is an articulated bus or trolleybus, featuring a diesel generator electric hub motors.
It all sounds rather unlikely, but trials started only in February 2001, so it is too early to comment. However Irisbus-Matra must be pleased with an early success in the US market, having been selected by Las Vegas for a US DoT-sponsored trial. At least they have got the system working, unlike the AEG buried-cable bus guidance system installed between Greenwich and the Dome, which never managed to get commissioned during the year that the Dome was open (despite working perfectly well in the Channel Tunnel emergency tunnels, and undergoing trials on Newcastle Riverside).
Which brings us to the latest contender, Translohr, on offer from the Lohr Industrie, a specialist vehicle manufacturer based near Strasbourg in the Alsace region of France. Lohr have reverted to mechanical guidance, seeking to address what they see as the drawbacks of the TVR. There is still a centre rail, but to a profile with sloping railhead sides. Each vehicle wheelset is guided by two modules at the outer ends of a box frame (substituting for the axle), and each module has two wheels fixed at 45° to the rail and 90° to each other which effectively grip the rail, thus preventing a module from jumping out of the guidance system. This is important, for unlike the TVR the guidance wheels exert no downward force on the rail, which thus requires a much less substantial substructure and reduces installation costs. The vehicle weight is transmitted through the rubber tyres (eight on the three-section prototype). Running vibration is almost eliminated, making the system smoother and quieter.
Two graphics from Lohr showing the wheelset design with triangular guidance supports, and the wheel/rail/road surface interface.
The prototype unveiled in July 2000 is equipped with a pantograph current collection system, with current return through the centre rail. As built, batteries provided limited off-track capability (there is a manual steering wheel system), but after a brief appearance in Paris on the relaid section of the Trans Val-du-Marne busway, the vehicle has returned to the manufacturer to have a roof-mounted gas turbine generator installed to permit more extensive off-track running, so that it can be used in public service over the whole busway.
The Translohr SE-3 prototype has been the subject of a great deal of design effort to produce what looks like a modern, well-designed low-floor tram, with the rubber tyres hidden under skirts. Three doors give access to a spacious passenger area with a floor height of just 250 mm. Much use of aluminium keeps the weight of the 25-m long, 2.2-m wide vehicle down to 19.5 t unladen. 116 passengers can be accommodated (32 seated) in an attractive environment created by the Italian coachbuilder Parizzi. Electrical equipment comes from Fiat (now owned by Alstom, which also supplies electrical equipment to Civis and TVR).
Those who have seen Translohr in action have come away impressed with its performance and build quality. The company has invested over FRF 100 million in the project and will need to achieve some sales within two or three years to start generating a return on that investment. Their salesmen are in particular targeting smaller French cities which would like a tramway, but doubt that they can afford it, plus some of the smaller German tramway towns which are finding life heavy-going financially. They have already persuaded Ulm to rewrite their tender for new trams to permit Lohr to bid the Translohr system, and this should be the first indication of the comparative costs.
All these systems are of course proprietary products, and once purchased the operator is locked in to the manufacturer, unlike the tramway product which is available from a wide range of competitive sources. Tram builders have been under pressure to reduce the cost of vehicles for some time, hence the appearance of modular ‘catalogue’ trams such as Combino, Citadis, Cityrunner, Cityway and Incentro. Other elements of the infrastructure, track and overhead, also need cost reductions if the conventional tramway is going to compete against the ‘tramway on tyres’. The forthcoming Alstom low-cost tramway demonstration in La Rochelle should be particularly significant in demonstrating how this can be achieved. The company is building a 1.5-km tramway close to its Aytré factory and test a ‘cut-price’ Citadis variant and associated infrastructure that should get the cost/km below that of the Nancy TVR.
There’s another one behind!: top