MALAYSIA

Kuala Lumpur's Light Rapid Transit System is an elevated oasis above the carbon monoxide-belching traffic. The beautifully clean air-conditioned air in the trains contrast with the hot humid air outside. Phase 1 costing US$120 million began in late 1993 and was finished in December 1996. This section runs eastwards from the downtown area of Sultan Ismail to the Ampang depot.

For anyone who has ridden on the London Underground or the Tokyo subway this must sound like a dream. But for concession company Sistem Transit Aliran Ringan (STAR), the low passenger numbers recorded during the first 17 months of operation have been disappointing.

The Main Contractor admits that the figures are worse than expected: "Patronage hasn't yet met the forecasts. There's been a huge increase in car ownership, and just like in any city people need to be converted," says the project director. But he is optimistic that once the other components of the integrated rail system are in place the situation will improve dramatically. "Each system will cross-feed passengers to the others. In two or three years' time when the other lines and major office developments are finished we win see a big increase in popularity," he says.

This should be helped by an integrated ticketing initiative currently being negotiated. Passengers will then be able to use a single electronic smart card to ride on all of the city's mass transit lines. The technology is already available, but the commercial controls win take longer to establish. "There will have to be a central collector and distributor of revenue and that won't happen overnight," he says.

Construction of the RM2.3bn (US$ 765 M) Phase Two extension of the STAR LRT is well under way and at 15km long it win more than double the range of the existing system. An added T branch from the south will allow twice the current number of trains to pass through central Kuala Lumpur. An extra third carriage will bump capacity up from 16,000 to 33,000 passengers an hour.

As in Phase One, the city centre sections of Phase Two are elevated above street level. However cement shortages prompted the Contractor to switch from prestressed concrete to steel composite designs for three of the five main structures in the southern section.

This in itself caused problems: The plate thickness of the steel was higher than anything produced in Malaysia so we had to get special permission to import," explains the Contractor. But he reckons the change was still far better than risking long delays from unpredictable concrete supplies. And it seems that the Malaysian government agreed. Not only did it give permission to import the steel, but it also allowed workers to be brought in from Indonesia and India to get around local labour shortages.

Despite the shift to steel for some of file structures, prestressed concrete viaducts are still a major feature. Phase Two will use 1,730 precast units manufactured at a yard 25km outside the city almost twice as many as in Phase One. Thanks to specialist software, each of the 2.7m long units should fit to the next as precisely as the pieces of a jigsaw puzzle.

The correct vertical and horizontal alignment is built into the segments by controlling the angle of the stop end during casting. The viaduct segments are erected using two 102m long launching gantries (see picture on left) tied to the deck with Macalloy bolts. Although originally built for a highway project in Melbourne, the gantries are the ideal machines for the snaking LRT alignment. The main truss of each is suspended through an "A" frame which allows it to pivot by a few degrees - enough to cope with the tightest 130m radius bends. Technical support for the launching manoeuvres is provided by French contractor PSC Freyssinet. "Freyssinet designs each complex move and then produces a series of cinematics. This allows the precasting yard to cast the gantry anchor points in precisely the right place, avoiding time consuming and inaccurate driving on site. During launching, the truss is pushed out through the A-frame to typically complete a 38m span in three hours. At the next pier head the end of the gantry is supported on friction clamped falsework. 'This means we don't have to do any unsightly through-bolts or box-outs," says the Contractor. This attention to detail and desire for a clean structure has been carried through the whole project. Although the fit of the viaduct segments is excellent, a precast concrete edging was added to enhance the smooth flowing lines.

In busy downtown Kuala Lumpur, the same aesthetic standards was applied to the new station structures. Pressure of space has meant opting for cantilevered platform slabs hung from tension piles or creating new footprint areas wherever possible.

This is perhaps best seen at the Putra World Trade Centre station which is being built above the River Klang. The structure will sit on two heavily reinforced 50m span transverse beams which are 7m deep at their midpoint. The centre of these will include a boxed-out area designed to increase longitudinal stiffness. "They have to be able to resist torsional forces as the trains roll over them," says the Contractor.

The fast track nature of the project and the immovable Commonwealth Games deadline of September 1998 has meant turning design work around extremely quickly. "On occasions we've had to change what we thought we were building at the last minute," says the Contractor. The day before concreting was due to start on the PWTC station, the planning department raised the flood design standard to a 1 in 100 year level - a move which meant raising the whole station by 2m.

The southern section of Phase Two will serve the new national stadium and Commonwealth village. To leave enough time for full testing of the system, a completion date of June 1998 has been set - six months ahead of the less critical northern section. Two of the southern stations are already virtually complete, allowing German MAE contractor Adtranz to get on with track testing.

Komanwel station at the Games complex is also taking shape. To fit in with the architecture of the new sports facilities it will have a Teflon-coated fabric roof suspended from curved tubular steel sections imported from the UK.

As well as looking the part, the roof could act as an interesting comparison. "Fabrics from the three main manufacturers are being used between our station, the stadium and the swimming complex," explains the Contractor.