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Cross country race

South East Asia -Taiwan high speed rail: One of the world's largest construction projects is being pushed through in record time. Adrian Greeman reports on Taiwan's high speed rail link

Expatriate engineers in Taiwan are bemused.

Though they are currently designing, inspecting, building, checking and controlling the country's new high speed rail project, one of the world's biggest construction projects, and certainly its biggest single railway scheme, no-one seems to have noticed.

'And we are doing it very fast, ' says KH Lee, senior vice president for the construction management division of the Taiwan High Speed Rail Corporation (THSRC), the private sector concessionaire for the scheme.

'How many single city metro lines would be done in five and half years? We are building an entire 345km of high speed railway to be operational by the end of 2005.'

Civils work began in March 2000 when the first of a dozen huge design and build contracts were let, ranging in size from $300M to $600M.

A total cost of NT$446.4bn for the railway and its systems, translates as US$15bn, around the price of the UK's Channel Tunnel. The figure excludes costs for land which is being supplied by the government for a 35 year build, operate, transfer concession period.

The new railway line is no metro, but a twin track, super speed line running from one end of the country to the other.

Japanese Shinkansen bullet trains, exported for the first time, will initially run at 300km/h, rising later to 350km/h, to connect the capital Taipei with Kaohsiung, the world's third largest port in the south. A five hour journey will be cut to a little over 90 minutes.

Initially five new stations will be included on the route, plus the terminals. Among them will be the world's first underground high speed station at Taiyuan, with through trains passing at full speed along a central cut and cover tunnel space.

Building the line is no easy matter. It must thread its way through the densely populated coastal plain on the west of the island and through hilly ground in the north. Like Japan, much of Taiwan is mountainous and 95% of its 24M population lives on the coastal strip on the west side of the island, which is rapidly becoming a linear city as major conurbations join up.

As a result, land prices are exceptionally high and road and rail corridors tend to be placed on viaduct to minimise land take. Some 242km of the new line will be raised between 5m and 25m above ground while another 48km will disappear into tunnels, some of them very difficult to build, in the higher ground close to the capital. Cuttings and embankments make up the remainder.

The viaducts will also help the line cope with the extraordinary climate in Taiwan where summer typhoons can bring staggering volumes of water, perhaps 800mm in a day. These downpours sluice off mountainsides up to 4,000m high and across the western plain, turning quiet streams into lakes. It helps to be above the flood line.

But building on viaduct is not without problems. Taiwan is one of the world's most active seismic zones, the result of a three way collision between tectonic plates. Along the north-south line of the island, where the mountains are being thrust upward almost daily, the Eurasian plate is dipping beneath the Philippine Sea Plate, though just north of the island the situation is reversed as the Philippine plate is forced beneath the Eurasian Plant.

The geological battle means earthquakes like the 7.8 Richter scale event of September 1999, nicknamed the '9/21' are not infrequent. Only last month a Richter 6.8 shaking caused damage throughout the island.

Structures, particularly for rail, have to be heavy, solid and well founded. Design codes tend to follow Californian practice with for example, heavy spiral reinforcement wrapping for containment in columns.

Unfortunately along most of the southern section of the rail, route firm ground is hard to find.

According to John Ager, a geotechnical specialist with THSRC, the coastal plain is made up of a combination of alluvial wash from the mountains and seabed deposits. In the north this is often gravels, sands, cobbles and conglomerates, particularly in foothill areas, but further south this becomes mainly recent alluvium of soft clays and silts.

Or to put it another way the project is being built on 'slop' up to 200m deep, says Jim Gainsford THSRC resident engineer on Contract 280, well towards the southern end of the route.

Typical of most of the southern sector contracts - the line is divided into two regions - this required huge amounts of piling, and since there is no chance of reaching a firm layer, friction piling is called for.

'The top 20m of the ground can liquefy in an earthquake so they must go pretty deep, ' adds Gainsford. 'Ours are up to 75m long and usually 1.5m in diameter.

Numerous subcontractors are still busy with a variety of old and new piling rigs along the 34km of route being built by the main contractor, a joint venture of Korea's Samsung, and Hanjung with local firm IE&C. With piers at 35m intervals in the north of the contract and 30m intervals south, there are plenty to install; some 3,000 of a total 5,200 piles were completed by March this year.

With thousands of piles also needed on the other contracts it might be thought demand had exceeded supply. But according to Jeff Hewitt, chief director for the southern regional office, the rail work has coincided with a downturn in government projects.

The Samsung contract illustrates the sheer scale of the project. The design calls for hundreds of beams to span the viaducts and the 800t, 3.5m deep and 35m long prestressed box sections are delivered as single units. Italian company Paola de Nicola has supplied launching equipment to this and many of the other contracts.

Like many contracts, 280 made a slow start, says Hewitt, not least he thinks because most contractors on the project underestimated the time it would take to get design work under way and checked, particularly in the light of stringent seismic requirements.

Contractors appoint their own consultants and must also appoint their own quality and checking engineers who in turn are monitored by the THSRC.

Designs are further independently audited by a government appointed engineer, the International Railway Engineering Group, led by UK firm Mott MacDonald.

The Korean group is now beginning to catch up, helped particularly by using cast insitu formwork.

'This gives more flexibility, ' says Gainsborough, allowing work to leapfrog longer bridge spans and crossings. As yet the first precast units are only just beginning to go into place.

Elsewhere on the project viaduct work is further ahead. On Contract 260, for example, Bilfinger & Berger is already several kilometres along using a similar Paola de Nicola launching system. A Kirow transporter takes the 35m long span units up to the launching beam, which carries the units on a travelling crab.

Units are formed in two casting beds alongside the viaduct and lifted on to it with two large gantry cranes. Bilfinger & Berger has a total 24km of viaduct to construct, including some shorter sections between cuttings, plus several tunnels, the only ones in the southern sector.

Further north still, eyes are on the Japanese-led Obayashi/ Futsu joint venture which has 41km long contract close to Taipei. Here the contractor has nearly 31km of viaducts and has subcontracted a major section to VSL which has set up a precast yard with three casting beds to service a special combined transporter and launching girder.

The VSL transporter has a long central beam and high wheeled tractors at each end.

These turn at right angles allowing the transporter to crab. Once it has picked up a beam the unit switches into forward drive mode to move the whole beam along the viaduct to a placing position. A support beam over the next piers allows the transporter to wheel out over the span and drop the beam into place.

Ground tends to be better in the northern half of the project;

just as well since it is here most of the tunnels are to be driven.

Both Bilfinger and Obayashi projects include major tunnels.

Bilfinger's is the Pakuashan, at 7,360m the project's longest, but located in relatively good ground. Obayashi has the Hukou, a 'mere' 4.3km but in saturated soft ground which at times is very hard going.

NATM methods are used on all the tunnels, which are twin track and typically about 12m high and 14m across at the widest point.

At Pakuashan a very clean and orderly atmosphere prevails, helped by the tunnel being completely dry and the ground firm, with generally compacted sands, gravels and cobbles.

Even so, Bilfinger works with just a 0.8m round before installing lattice arches and shotcrete support; monitoring is carried out at 10m intervals, with instruments reading back to its office.

According to Bilfinger engineer Martin Wagner, the contractor made sure it imported precisely the equipment it wanted including a purpose built Liebherr tunnel excavator; the 360infinity rotating arm means the bucket can be angled to get a clean tunnel profile. Wagner uses Caterpillar equipment - the best, he says - to load spoil and haul it away.

Work on five faces has been making a good 150m a week.

Further north on Contract 215, Obayshi has to cope with much softer, wetter ground with a water table sitting just 1.5m below the surface in overburden that rises to around 100m. Dewatering 25m ahead of the face to a level 20m below the invert helps initially but the loose sand and silt still needs shotcrete support on the face. Shotcrete, mesh and lattice arches provide basic support supplemented as needed with extra shotcrete, and ground anchors.

'The contractor stabilises the face 18m ahead by grouting and also uses forepoling in 12m lengths says RE Garry Page.

Making sure all these disparate elements stay on course is the major task facing the regional offices, says northern chief director Peter Humphries.

'Each of these contracts would be a good size project itself elsewhere, ' he adds.

Where there are delays, they can be recovered, he thinks, and the self-monitoring system of the contracts is 'going better than I thought it would, given that it is new to Taiwan'.

There is a long way to go, but for the moment the planned 2005 opening date is being held to.

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