May 2006 issue of a newsletter I wrote for the KPE project

1. 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

2. 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 Update
About 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

3. As Good As New
Works in other areas have progressed well.
We reinstated Stadium Walk / Stadium
Crescenton15February2006.Weareinthe
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 ECP
Another 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 ECP
Just 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.

4. 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 fire
A steel enclosure was built to protectthe tunnel interior during the test
Smoke b
portal a
w
Ventilation Building ‘A’ is one of the six ventilation buildings along the KPE alignment

5. bellowed out from the tunnel
after the six trays of kerosene
were ignited within the tunnel
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 Constructors
mobile: 9857 8777
FEEDBACK
Land Transport Authority
No. 1 Hampshire Road, Singapore 219428
Customer Service Line: 1800 225 5582 Fax: 6396 1148 Website: www.lta.gov.sg

6. 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
422tunnel.Withthiscloseencounter
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 in
the KPE tunnel
Senior Project Manager,
Mr Lee Chian Heng (second from left)
leading our guests for the visit to the
Geylang River site