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Third-rail trams across the Garonne

01 Feb 2004

France's ninth modern tram network began carrying passengers in December, and work is getting underway on the first of seven extensions. Chris Jackson looks at Bordeaux's innovative surface-contact power supply

TRAMS RETURNED to Bordeaux with a bang on December 21, when a firework display marked the inauguration of Line A by President Jacques Chirac and Mayor Alain Juppé. But despite the celebrations of 'T-Day', completion of the first phase of the network has been postponed once more in the light of technical problems.

Plans for a six-car convoy conveying the VIPs and over 1000 guests along the route were scaled back after fireworks of another kind shortly before the opening ceremony. Thousands of residents had turned out to ride the free services which started at 05.00 on the launch day. But at 09.00 a metal noise shield fell off a tram, short circuiting the ground-level power supply. Services resumed, but a similar flashover occurred an hour later, leading to the decision to cut back the opening ceremony. After visiting several of the city centre stops to meet local residents, Chicac and Juppé were only able to ride the inaugural tram for a few hundred metres from Place du Stalingrad to initiate the firework display on the historic Pont de Pierre over the Garonne.

Despite the problems, revenue services on Line A began as planned on December 22. Head of the tramway project team François Saiglier insisted that the flashovers were caused by a vehicle problem rather than a generic fault with the power supply. But Juppé revealed on January 5 that the opening of Lines B and C scheduled for February 28 would be postponed, so that the contractors could concentrate on resolving 'ongoing technical issues' on Line A. He hoped to announce a new date before the end of the month, but this was subject to further consultation.

When the other two lines are ready, operating concessionaire Connex plans to restructure the local bus network to feed the three tram routes. According to Connex spokesman Xavier Tersen, the light rail network has provided the opportunity to revitalise the whole image of Bordeaux's public transport. 'Even those communities which will not be served directly by the trams will get something for their financial contribution in the form of an enhanced and refreshed bus service', he explained.

Three-line network

Promoted by the Communauté Urbaine de Bordeaux, the light rail network has been built and equipped by a seven-company consortium led by Alstom Transport (MR 02 p29). Total cost of the 43·7 km due to be completed by 2007 is put at €1·05bn at current prices, of which the 24·5 km initial phase accounts for €646m. CUB has provided 65% of the funding for Phase 1, with 15% coming from central government and the remainder from loans. There is still some uncertainty over central funding for the second phase, but Juppé pledged in January that the extensions would go ahead using locally-raised finance.

As with other French cities, Bordeaux has used the light rail project to spur a facelift to much of the city centre. Five eminent designers and architects were employed by CUB to develop different aspects of the project, including the urban remodelling, rolling stock and depot.

Buildings are being cleaned, and traffic re-routed to allow the pedestrianisation of several streets. Grassed reservations and avenues of new trees flank parts of the line, and elegant new street furniture abounds. The tram routes are edged throughout with rows of carved stones, with stainless steel logos embedded into each block. The stylish modern tram stops feature etched glass name panels which suggest that expense has not been a prime concern.

Line A starts outside the CUB offices at Mériadeck and runs east through the city to cross the Garonne via the Pont de Pierre. It then runs on grassed central reservation along Avenue de Thiers, splitting into two branches serving Lormont and Cenon. Line B runs from Place des Quinconces on the west bank of the Garonne southwest to Talence, interchanging with Line A by the cathedral at Place Pey-Berland. The short 2·8 km Line C follows the west bank south from Quinconces to the main SNCF station at Saint-Jean.

Innorail innovation

A distinguishing feature of the Bordeaux network is the absence of overhead wires in the central area. When the original tram network was built, the city authorities adopted a conduit power supply for the tram network, to protect the visual image of the city centre as laid out by Baron Haussmann at the end of the 19th century, and this lasted until closure in the 1950s. When CUB decided in 1996 to reintroduce light rail, bidders were again invited to put forward proposals for propulsion systems which would avoid the need for wires.

Options considered included battery, flywheel or diesel powerpacks, but all of these would have posed operating restrictions due to the limited power availability. Eventually the choice fell on the Innorail APS (Alimentation par Sol) ground-level power supply system. Innorail was originally formed as a wholly-owned subsidiary of electrification specialist Spie Enertrans, but when that firm was acquired by Amec it sold its shares in Innorail to Alstom.

Getting approval of the APS equipment under new French safety-case regulations proved one of the time-critical factors in commissioning the network, according to Alstom Project Director Hubert Peugeot and Innorail Managing Director Antoine Picard. Test running was undertaken on an isolated 500m section in Lormont, which could be physically sealed off from other road users. After formal tests and an independent audit, the safety case was finally signed off on October 21, allowing commissioning trials on the remainder of the network to start barely two months before 'T-Day'.

Peugeot attributed the year's delay in opening the network to civil engineering problems in the early stage. Under the original contract, he said, the civil works were due to be handed over to the systems consortium by mid-2002, but by that date barely two-thirds had been completed. CUB approved a 12-month extension until July 2003.

Even before APS received its safety approval, it had already become clear that all three routes would not be ready in time. The CUB tramway project team decided to concentrate all efforts on completing Line A, and postponed the opening of Lines B and C to February. However, in early October one car was towed through the uncompleted junctions, across the city centre and out to Pessac. This enabled the start of gauging runs and commissioning on the overhead-equipped section of Line B from the outer terminus inwards.

Digital radio switching

APS relies on digital radio signals to energise short sections of a central third rail under the vehicles, providing a full 750V DC supply to each car as it passes. The first phase of the Bordeaux network has been fitted with around 10·5 km of APS, split into five sections over all three routes. As well as the city centre tracks, short lengths of APS have been installed on both eastern branches of Line A at the wish of the local communities. It is also being used on part of Line B, where the fire brigade wanted unfettered access to buildings along a narrow street.

The centre rail has two raised contact strips on the head, about 20mm wide, separated by a 10mm recess. The rail is laid slightly higher than the running rails, so that the pick-up shoes pass above the running rails at pointwork. The contact rail is split into 8m sections, separated by 3m glass fibre inserts to form an isolation gap. The power is fed via 980 switching boxes set into the track, each of which powers two adjacent 8m lengths.

The two sets of pick-up shoes on each car are carried at opposite ends of the single unpowered bogie, immediately beneath the pantograph. The shoes are spaced 3·2m apart to bridge the insulated gaps and ensure continuity of supply. The cars were initially fitted with cast iron pick-up shoes to help polish the contact surface of the newly-laid rails. After a few months the shoes will be replaced by softer carbon pick-ups to avoid excessive wear.

Changeover between overhead catenary and APS modes takes place while the vehicle is stationary at a stop. The driver presses a button to initiate an automated sequence which lowers the pantograph and extends the parallelogram-mounted shoes to engage the contact rail. Each car is also fitted with emergency batteries which will allow it to run for up to 1000m should it become isolated from the third rail or overhead supply.

To energise the ground-level supply, each LRV operating in APS mode repeatedly broadcasts an 8-bit digital message to an antenna under the contact rail. The radio message is broadcast as a conical signal no more than 100mm in diameter at ground level, to avoid any risk of cross-energising the adjacent track. Only when a switching box has received and identified the 8-bit message four times in quick succession will the relays energise the appropriate section of rail.

The positioning of the shoes and radio antennae is designed to ensure that the rail is only live underneath a vehicle. Changeover contacts on the track-mounted switchgear earth the centre rail to the running rails at all other times, to avoid any risk of a residual potential.

In the event of any fault, each switchbox is designed to fail safe and isolate both rail sections. An alarm will be triggered at the control centre, but the service should be able to continue with the cars coasting across the gap. The faulty switchbox will be replaced during the night, with quick-release connections for a rapid change-over. Defective boxes will be returned to the supplier's workshop for servicing.

Articulated cars

All three routes are intended to run at 8min headways off peak, with trams every 4min at peak times. This gives a nominal capacity of 4500 passengers/h in each direction on the two main routes and 3000 passengers/h on Line C. Services operate from 05.00 to 01.00 each day, and the commercial speed including stops is 21 km/h.

The initial network is worked by a fleet of 44 Citadis LRVs supplied by Alstom. Six of these are 32·8m five-section Series 302 cars for Line C, able to carry 66 seated and 134 standing passengers. The remainder are seven-section Series 402 cars 43·9m long, with 90 seats and space for 210 standees.

Due to delivery constraints, all the cars were built by Alstom's La Rochelle plant as five-section vehicles. The extra motorised articulation modules and saloon sections were fabricated in Barcelona and fitted to the cars following delivery to Bordeaux. All the vehicles are being named after towns and cities which have civic links with the communities in the Bordeaux conurbation.

Alstom's contract includes options for a further 12 Citadis 402 cars and eight more 302s. These would bring the fleet to 70 vehicles when the second phase of the network is completed around 2007.

At present all cars are stabled, serviced and maintained in a single 7000m2 depot at La Bastide, reached by a short branch from Line A in Avenue de Thiers. Although this includes provision for four more stabling roads, CUB plans to develop a second servicing depot on the northern extension of Line B.

Connex employs around 2000 staff on its Bordeaux operations, including 1250 bus drivers. Of these, around 170 have been trained to drive the trams, and will work a three-week shift pattern covering two weeks of tram driving and one of buses. At present the company only has 14 staff based at the maintenance depot and operations control centre, as the suppliers are responsible for maintaining the network and cars for the first year of operations. Innorail has a separate 10-year contract to maintain the APS equipment on Phase I.

Phase 2 gets underway

Even before the inauguration of Line A, work had started on the first of seven extensions forming the second phase. These are due to be ready by 2007, despite the uncertainty over the funding arrangements. According to CUB's Thierry Ficat, priorities have yet to be agreed for the various extensions. Initial project studies have been completed for each section, and more detailed design is now underway with the aim of starting work around 2006.

The first section to be authorised is a 1 km western extension of Line A from Mériadeck to the CHR hospital complex, which is costed at around €80m. Utilities diversion has started and trackbed construction is beginning on this section, which forms the first half of the Line A extension to Mérignac, just short of the city's airport.

At the eastern end of Line A, phase 2 includes short extensions to both the Lormont and Cenon branches, bringing the total length (with Mérignac) to 19·9 km and 27 stations. Line B will be extended northeast from Quinconces to Claveau and north from Pessac to another interchange with SNCF, bringing it to 15·4 km and 20 stations. Line C will run north from Quinconces to Aubiers and south from Saint-Jean to Boulevard Jean-Jacques Bosc in Bègles, serving seven stations in its 8 km length. The completed network will serve nine park-and-ride interchanges offering more than 5000 parking spaces.

APS will be used on 3·5 km of the Phase 2 extensions, including the bulk of the Mériadeck - CHR section where the fire brigade have again requested clear access to the hospital buildings.

The contract price for the APS equipment on Phase 1 was €1·5m per track-km, which is around three times the price of the conventional overhead sections. For the CHR extension the price has increased to €2m, although some observers suggest that the true cost may be nearer €3m. Picard says the price is likely to come down in the longer term as the technology is used more widely, and notes that Nice and Paris are among several cities that have already expressed interest in using a third-rail supply.

 

  • CAPTION: After participating in the formal opening ceremony at La Bastide depot, President Jacques Chirac (centre) and Mayor Alain Juppé (speaking) rode the inaugural tram to trigger the firework display at Pont de Pierre (top)
  • CAPTION: Lines A and B cross at right angles outside the cathedral in Place Pey-Berland; the centre rails on all four tracks are isolated
  • CAPTION: Two 8 m sections of live rail are energised from each feeder box; when not in use the contact rail is earthed to the running rails by changeover switches (inset)
  • CAPTION: Operation of the three-line network will be managed from a single control centre (below) located next to the workshops at La Bastide depot (right)
  • CAPTION: The inaugural Citadis 402 leaves the depot at La Bastide with the VIP guests on 'T-Day', when thousands of Bordeaux residents flocked to ride free on their new trams
  • CAPTION: Two sets of pick-up shoes are mounted under the pantograph section of each car, spaced 3·2 m apart on each side of the bogie
  • CAPTION: As prime contractor,Alstom was even responsible for providing and planting the architect-specified trees that flank the grassed Line A reservation along Avenue de Thiers east of the river bridge

Principal suppliers

Maîtrise d'Oeuvre Groupement des Etudes du Tramway (Systra, Ingerop and Thales)

Urban planning Brochet-Lajus-Pueyo

Workshop design Jacques Ferrier

Turnkey contractor Alstom-led consortium: Alstom, CMR, Sogefi, Moter, Spie Trindel, Fayat, Amec Spie Rail, Vossloh Cogifer

Operator Connex Bordeaux

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