Issue 4, May 2006Contract 421 - ECP to Nicoll Highway

The Kallang/ Paya Lebar Expressway (KPE) project is

Singapore’s most complex expressway project to date.

With 9 kilometres of underground tunnels to construct,

engineers have had to face challenges ranging from

deep marine clay valleys, a network of underground

utilities, tunnel construction under the operational

east-west MRT line, and tunnel construction under the

Geylang River. For Contract 421, the tunnel works at the

Geylang River has offered the greatest challenge to the

project team.

As part of the preparation work for the river diversion,

a cofferdam was constructed on the north bank of the

Geylang River (see figure 1). The tunnel structure was

then built within the cofferdam. Temporary works for

the future main river diversion were then installed and

Geylang River was diverted to the north side and on top

of the completed KPE tunnel structure. This phase of

work was completed in June 2004.

After the successful diversion of the Geylang River over

the completed tunnel on the north bank, double sheet

pile cofferdams were installed across the old river course

and filled with sand (see figure 2). Another sheet pile wall

was then installed within which excavation for the KPE

tunnel can be carried out. Water was then pumped out

from the area within the cofferdam to allow excavation

of the tunnel to begin (see figure 3).

The Story of Geylang River diversion

We have adopted a Top-Down Construction method for the Geylang

River section due to the deep soft ground. The sequence of works

involves excavation and installation of steel struts to the level of the

tunnel roof slab, followed by the construction and casting of the

tunnel roof slab. The 3m thick tunnel roof slab provides a massive and

rigid support across the excavation site. Excavation below the roof

slab is then carried out through access openings left in the tunnel

roof slab. The excavation is taken down layer by layer to the tunnel

base slab. The base slab will then be concreted. The side walls of the

tunnels are then constructed between the roof and the base. Once

the full tunnel structure is completed, the access openings on the roof

slabs are sealed (see figure 4). The river is then diverted back to its

original alignment and the river walls reconstructed (see figures 5 &

6).

Progress UpdateAbout 85% of the tunnel roof at the Geylang River section has been

completed. To ensure the stability of the works, a jet grout block is

being installed in front of the PUB substation. Jet grout piling is

expected to be completed in April 2006. Following this, the remaining

section of the roof will be completed and the next stage of excavation

below the tunnel roof progressed across the entire area. The project

team is planning to complete the tunnel across the Geylang River

within the next 10 months.

Excavation under the tunnel roof slab at the Geylang River

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

As Good As NewWorks in other areas have progressed well.

We reinstated Stadium Walk / Stadium

Crescent on 15 February 2006. We are in the

process of handing back the reconstructed

Kallang Practice Track and football

field to the Singapore Sports Council.

Reinstatement works at the Stadium

Boulevard / Stadium Drive junction are in

progress and will be completed by June

2006. The reinstatement of the stadium

area between Jalan Benaan Kapal and

Nicoll Highway is almost complete. Our

engineers are working hard to ensure

that the area near car park ‘F’ and Stadium

Drive would be ready for the National Day

event.

The winding temporary Stadium Drive will

be realigned to its final location sometime

in June 2006 after the backfilling of the KPE

and CCL tunnels below the road junction.

Motorists will soon have a smoother ride in

and out of the stadium area.

South of the ECPAnother completed section is the KPE

tunnel below the Ventilation Building ‘A’.

The remaining works to the building are

erection of the perimeter fencing and

landscaping for the area. This is being done

by the National Parks Board.

Works at North of ECP

Kallang Practice Track & football field have been reinstated

North of the ECPJust north of the ECP, the construction of Slip Road ‘A’ tunnel structure

connecting the ECP to the north bound KPE tunnel is in progress.

Construction of Slip Road ‘B’, the exit slip road from KPE south

bound tunnel joining ECP (Changi direction) is going at full pace

and sheet-piling works are nearly completed. Excavation works

and structural works are progressing well. Jet grout piles for soil

improvement are being installed in the pump sump and shallow end of

the slip road due to presence of soft material below the tunnel structure.

Construction of the main tunnel between the ECP and Tanjong Rhu

is also in full swing. Excavation and strutting works have reached the

tunnel formation level. The casting of the first base slab at one of the

widest excavation in the KPE road interchange has been completed.

On 18 January 2006, KPE project team

conducted a series of hot smoke tests in

the KPE tunnel at KPE slip road “D” under

the East Coast Parkway (ECP).

The tests allowed our engineers to

verify the effectiveness of the tunnel fire

protection and ventilation systems in the

event of a fire within the KPE tunnel.

For the first test, six numbers of A1 size steel trays

containing 9 litres of kerosene were ignited to

simulate a 5 MW fire. Two minutes from the onset

of the fire, two tunnel ventilation fans located in

the ventilation building were activated to extract

the smoke generated from the fire. Smoke from

the fire was effectively channelled away from

the escape path and was extracted and removed

through the KPE ventilation building “A” located

South of the ECP.

6 nos. of A1 size steel trays & 9 litres of

kerosene were used to produce a

5 MW fireA steel enclosure was built to protectthe tunnel interior during the test

Smoke bellowed out from the tunnel portal after the six trays of kerosene

were ignited within the tunnel

Ventilation Building ‘A’ is one of the six ventilation buildings along the KPE alignment

Smoke bellowed out from the tunnel portal after the six trays of kerosene

were ignited within the tunnel

Ventilation Building ‘A’ is one of the six ventilation buildings along the KPE alignment

Smoke from the fire was successfully extracted out through the exhaust stacks of the ventilation building within minutes of the fire being detected in the tunnel by the Linear Heat Detectors

For the second test, the same procedures

were repeated except that the speed of

the tunnel ventilation fans was varied to

operate together with the jet fans in the

tunnel.

For both tests, the Fibre Optic Linear

Heat Detector proved to be effective in

detecting the rise in tunnel temperature

and activating the alarm. The Linear Heat

Detectors were able to detect heat from the

hot smoke within 45 seconds.

The tunnel ventilation fans and tunnel jet

fans were successful in extracting the smoke

away from the escape path within minutes

during a fire. All in all, the tests were a great

success!

If you have feedback or suggestions, please contact:

Mr Michael Yap, Deputy Manager, Community Relations, Land Transport Authority mobile: 9831 4546 tel: 6396 1600 email: michael_yap@lta.gov.sg

Mr Arran Tan Public Relations Officer of SembCorp Engineers and Constructorsmobile: 9857 8777

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Land Transport AuthorityNo. 1 Hampshire Road, Singapore 219428

Customer Service Line: 1800 225 5582 Fax: 6396 1148 Website: www.lta.gov.sg

A group photograph with our guests taken inside the KPE Contract 422 completed tunnel

On Saturday, 7 January 2006, 25 guests comprising members of the Tanjong Rhu Neighbourhood Committee (NC), condominium managers and residents in the Tanjong Rhu area and representatives of Mountbatten Constituency Office visited the KPE tunnel. The visit was jointly organised by the Mountbatten Constituency Office and the Land Transport Authority.

Mr Lee Chian Heng, Senior Project Manager for KPE Contract 421 conducted a short briefing before leading the visitors for a site tour at the Geylang River site and a short tour of the KPE Contract 422 completed tunnel. Our guests were shown some of the key Electrical & Mechanical installations and safety features at the completed Contract 422 tunnel. With this close encounter and guided tour of KPE site, our guests gained a better appreciation

of the scale and complexity of the construction work at the Geylang River, as well as received an update of the construction progress directly from the KPE team.

Mr Ronnie Lim, Chairman of the Tanjong Rhu NC, thanked the KPE team for organising the site visit. He expressed the members’ appreciation of the opportunity to visit the KPE site.

Mr Chuah Han Leong, Deputy Director, KPE pointing out to the visitors, some

of the unique E&M features inthe KPE tunnel

Senior Project Manager, Mr Lee Chian Heng (second from left) leading our guests for the visit to the Geylang River site