INTRO: Alstom Transport’s Citadis low-floor tram family was unveiled at La Rochelle on September 2. Chris Jackson took a ride

ON A WARM sunny afternoon, a dark blue low-floor tram decorated with seagulls is being put through its paces on the Alstom test track in the French port of La Rochelle. Around 500 km to the southeast, an identical car undergoing commissioning trials is tantalising the citizens of Montpellier awaiting the opening of their city’s first light rail line.

The two cars are the first examples of Citadis 300, the light rail representative in Alstom’s Optionic Design range. Five cities have already signed up for Citadis, bringing the order total to 121 with further options for 47. Close behind the third Montpellier car on the Aytré production line are the first vehicles for Orléans and Lyon, while cars for Dublin and Valenciennes are on the drawing board. Montpellier placed its order on July 27 1997, and the first car was delivered two years and three days later.

Marketed as ’the spirit of your city’, Citadis is intended to offer unique designer-styled vehicles for each customer, with totally different cab ends, whilst minimising production costs through the incorporation of standard components and equipment modules. These draw heavily on the best existing designs within the group, such as the motored bogies from the Alstom-LHB cars for Magdeburg, the Onix IGBT-based traction drives and the Agate microprocessor control system.

The Montpellier cars have 70% low floors, with a complex mix of slopes and steps to carry the gangway over the power bogies to reach low-floor entrances behind the cab at each end. Wheel wells and equipment are located in boxes under the seats, leaving the interior clear to give a feeling of spaciousness.

The main low-floor area at the centre of the car includes space for wheelchairs, prams, and bicycles. This includes a low-floor gangway through the articulated centre section, which is carried on an unpowered Arpège truck with four independent wheels; controversially this has no primary suspension, which poses questions about ride quality. The 100% low-floor version selected by Lyon will use an Arpège truck with individual hub motors (Metro Report 99 p21) .

Citadis 300 cars are available in various lengths from 22 to 43 m. Emphasising the designer-led nature of Optionic Design, the Montpellier, Orléans and Lyon cars are all of different widths (Table I), though destined for new light rail lines which could easily have been constructed to common specifications. Alstom says this reflects the flexibility of the concept to suit existing cities with differing standards, but in future the company may try to influence buyers towards standardisation using price.

To suit the high level of flexibility in the concept, Alstom has developed a complex body structure formed of pre-assembled modules. These can be built and tested ’off-line’ and are then bolted and riveted together at a late stage in the production process.

Critical to the structure are a linear underframe and roof welded from alumnium extrusions. The high-floor areas over the powered bogies are steel to provide additional strength. Vertical frames can be located at any point along the sides to carry the door modules, which come complete with leaves, mechanism and controls. Aluminium end rings complete the structure, onto which can be bolted a complete cab assembly or articulation.

Driver protection in the event of a collision is provided by a circular bar at knee height designed to withstand a 200 kN compression load. A reinforced side wall structure with horizontal members at seat level provides additional side impact protection. To prove the concept, a Citadis bodyshell has been fatigue tested to 10 million cycles. Despite the restricted space under the floors, Alstom has found space for 100mm thickness of sound insulation above the motor bogies, bringing the predicted interior noise level down to 65 dB(A) at 50 km/h.

The bolted body structure allows for rapid repair by replacement; Alstom expects to be able to change a window in 10min and a complete side panel in just 20min. Within the structure, most equipment is arranged as plug-in pull-out modules with standard interfaces, allowing inverter controls, traction modules and other elements to be replaced in minutes. The company is also offering a centralised parts service with guaranteed delivery times, which would enable cities to minimise the cost of holding spares.

A growing family

Under the Optionic Design programme, the Citadis family is being expanded to encompass other low-floor LRV designs. Thus the all-steel cars being built by Konstal in Katowice for Warszawa will form the basis of the Citadis 100 being offered to Gdansk and Katowice. The stainless-steel Magdeburg design from Alstom-LHB in Salzgitter will be transformed into Citadis 200, whilst the Aytré family are all grouped under the Citadis 300 brand. Finally, Alstom is planning a Citadis 500 for dual-mode operation on tram and heavy rail corridors.

Alstom is currently bidding to supply Citadis in Istanbul, Melbourne, Bern, Rotterdam, Amsterdam and Bordeaux. Once the production lines are rolling at Aytré, plants at Barcelona, Salzgitter and Katowice and perhaps in Brazil will be equipped for local assembly.

TABLE: Table I. Citadis 300 variants

Montpellier Orléans Lyon Dublin

Layout Bidirectional Bidirectional Bidirectional Bidirectional

Gauge mm 1435 1435 1435 1435

Power supply V DC 750 750 750 750

Length mm 29826 29866 32326 32326

Width mm 2650 2320 2400 2400

Height mm 3270 3270 3270 3270

Low floor 70% 70% 100% 70%

Floor heights mm 350/600 350/600 350 350/600

Seats 58 40 57 58

Crush load 205 176 200 188

Top speed km/h 70 80 70 70

Designer Garouste et IDPO Renault not yet

Bonetti Design appointed

CAPTION: VIP guests and industry experts were invited to sample Alstom’s Citadis 300 at the Aytré plant in La Rochelle on September 2

CAPTION: Below: the centre section of Montpellier’s third Citadis car takes shape on the Aytré production line. Side panels and door modules are bolted to the welded floor (inset)