MTR’s project to build a high speed rail link to mainland China has had to overcome some tough challenges to remain on track for completion in 2015.
A year ago, MTR’s massive £5.47bn high speed rail project, known as XRL, was well into construction, but had run into problems.
The vast high speed terminus is still targeting a 2015 completion after hitting the doldrums in early 2013 as contractors on adjacent works packages struggled with interface issues, late running diaphragm walling, and a vast amount of excavation work, as well as shortage of labour.
Further north, a tunnel boring machine TBM heading towards the terminus hit an uncharted row of H-piles, slowing the tunnel construction programme while they were removed.
The 26km high speed link project comprises the vast West Kowloon Terminus site, connected to tunnels taking the link to the border with mainland China where it connects with China’s growing high speed rail system (see map p2).
The 11ha, 15 platform terminus is being constructed in a vast excavation within a huge 1.6km diaphragm wall. Tunnels immediately to the north are being driven through densely populated West Kowloon, with much of the alignment running through unpredictable reclaimed land, passing under high rise blocks of flats, live railway lines, motorway viaducts and drainage box culverts.
Bringing together teams across the site has helped everyone see the bigger picture and boosted morale
The terminus is being constructed in what is effectively a four storey basement, with four contractors working in adjoining areas.
They all have to share access points for bringing materials onto and off site, and must also coordinate construction of structures which will eventually join together, with floor slabs propping perimeter diaphragm walls now held in place by huge berms of unexcavated material.
By early 2013, the programme was flagging as contractors struggled to get to grips with the sheer scale of the project, interface issues and delays caused by unforeseen ground conditions and utility diversions. MTR Corporation projects director TC Chew decided that action was needed to give the project some added momentum, so he drafted in his chief civil construction engineer Alan Myers onto the terminus site to take charge.
“There had been some delays to all contractors that were not attributable to them,” says Myers.
“There was also an underlying feeling that the terminus was too difficult to build. There were also interface issues between the four major contracts which needed to be managed.”
Myers decided that to claw back the delays more had to be done to get the contractors to work together. He introduced bi-weekly meetings of the boards of the joint venture contractors, their project directors and the MTR project managers at which a holistic view of what was needed to get the terminus project finished was developed, so that everyone bought into ways to accelerate the programme.
At the same time, a logistics team made up of MTR staff and representatives of all contractors was established. This team constantly reviews site access logistics and runs an online booking system through which all deliveries must be booked. This ensures that materials arrive on site when needed, that cranes can be booked and holding areas designated for deliveries. It has been a vital asset considering that around 40 trucks enter or leave the site every hour.
The HK$3.5bn (£276M) XRL stabling sidings and an emergency rescue station at Shek Kong has reached the fit out and track laying phase.
Here tunnels from Kowloon move into a relatively shallow cut and cover section in a mountain valley from where trains emerge into an at grade sidings and a train maintenance area.
So far contractors have built a vast 500m long train maintenance shed - the length of two high speed trains - mainly from precast concrete elements to reduce the need for site labour.
This site also includes sidings and an almost 30m deep open cut box, within a 54m maximum depth diaphragm wall.
This three track section includes a central platform from which passengers can be evacuated in an emergency and two tracks for through trains.
Myers has also encouraged site teams to work on ways to hand over civil and structural work to follow on trades as soon as possible. In one area this meant inserting structural columns into large diameter boreholes before excavation was finished.
This enabled the contractor to use them to support top down floor slabs, cutting out the need to use temporary steelwork until the columns had been lowered into place through the structure. This resequencing saved time and opened up floor areas for the mechanical and electrical teams earlier.
Myers feels that bringing together teams across the site has helped everyone see the bigger picture and boosted morale.
“People started to see there were opportunities for them - not just for MTR - opportunities for them to make it easier for themselves, for example by sharing workplace security systems, construction equipment and the use of barging points,” he says.
And in the last 12 months, work has visibly progressed. Structures have emerged from the four storey basement excavation, and on the east side of the site a huge temporary steel structure is taking shape, to support the first of a series of tree-like tubular steel mega columns for the curved roof and glazed facade at the entrance.
Meanwhile, tunnelling work north of the West Kowloon Terminus has presented different challenges to contractors working to the north and south of an access shaft at Nam Cheong.
Last January the slurry TBM working on the first of two bores south of the launch shaft at Nam Cheong towards the terminus came across an obstruction, suddenly losing face pressure with the shield working at 3.5bar.
Contractor Dragages Bouygues discovered that the cutter head had started to chew into a row of uncharted, bored H-piles. Further investigations showed that there was a thicket of these piles in the path of the TBM.
Work on this part of the project had to drive slowly to allow tunnellers working in compressed air from the cutter head to painstakingly cut out the piles, removing them in pieces through the TBM.
The incident triggered an urgent review of the tunneling programme, and MTR has worked closely with the contractor to seek a way to reorganise work and claw back the delay.
An almost complete cut and cover section including stabling sidings will be ready by April 2014 to receive the first high speed train
It soon became clear that the main priority was for electrical and mechanical (E&M), trackwork and overhead civil teams to gain access to the down track tunnel where the TBM was stuck as soon as possible so that they could start track laying and installing track side related equipment linked to plant rooms at the terminus.
This meant that concreting for the invert slab and side walkway of the TBM tunnels had to be brought forward so that the down-track tunnel could be handed over to the E&M teams as soon as possible.
MTR decided to ask the contractor to stop concreting the invert slab and walkway in the completed northern section of the up track tunnel and shift its team to start work in the completed part of the stalled down track bore.
“We wanted to give this section to the E&M team to finish the down track, so that we could make this section available for tests,” says MTR XRL general manager Antonio Choi. This decision has helped claw back six months of the delay.
Further north, the adjoining drill and blast tunnel is progressing well. Contractors working from each end have overcome initial problems caused by faulted zones and now have only 700m of the 7.2km bore to go. “At one stage they were blasting 50m a week,” says MTR XRL tunnels project manager Bill Clowes.
Beyond that, an almost complete cut and cover section including stabling sidings (see sidings box, left) will be ready by April 2014 to receive the first high speed train.
This gives way to another 2.56km drill and blast tunnel which broke through at Kwai Chung last summer. This in turn joins onto the final TBM section which runs to the border with mainland China. This section is heading for a tricky cavitied marble section of ground.
“We will need to do some probing ahead of the TBM and will have to do some grouting,” says Choi.