ID 2

55

7

The greatest challenge faced was

that the segments were 20.34m

wide with rather thin concrete

sections. Vibrations during

transportation could cause

cracking and so most required

fitting with temporary props before

setting out on the journey.

Travel was at low speed to

minimise vibration. The segments

adjacent to the pier had to be

strengthened by temporary

strutting and increases to the

bottom slab thickness to allow

nailing of deck to pier during

cantilever construction.

components had been modified,

strengthened and upgraded to suit the

latest project.

VSL Malaysia in joint venture with

precaster Projalma was awarded a

contract for the casting and erection

of 747 precast segments, weighing

between 80t and 120t, and the supply

and installation of 1,100t of post-

tensioning. The segments were cast

in Ipoh – approximately 200km from

the Subang site - and delivered to a

point directly beneath the gantry. The

viaduct was built by the free-cantilever

method and segments were lifted up

in pairs using VSL’s strand lifting

units.

VSL JV’s scope of work included

provision of the casting yard at Jalan

Gopeng, Ipoh, including steel moulds,

the straddle carrier system,

reinforcement jigs and the bar

bending yard for the 747 segments.

The scope also covered provision of

the storage yard to store and cure the

segments, the supply of rebar,

concrete and prestressing

components, and the trailer to deliver

the segments to site.

Scope of works performed

• Design and supply of the launching

gantry

• Segment casting and erection

• Supply and installation of post-

tensioning

Subang Kelana Jaya Link is an

elevated highway in Subang Jaya,

Selangor, Malaysia. At the time of

construction it was the tallest

elevated highway in the region.

The project saw a return to action

for an overhead launching gantry

previously used on the Malaysia-

Singapore Second Crossing

Bridge, the Pakse Bridge in Laos

and the Bayan Baru Viaduct in

Penang. The gantry had first been

used in 1995, before being sent to

Laos in 1998 and returning to

Malaysia for the Bayan Baru

Viaduct in 2002. On the Subang

Kelana Link, it was used to build

the 34 spans of an elevated viaduct

consisting of precast segmental

twin-cell box girders. It was

assembled at the Subang site in

September 2006, after some

Subang Kelana Link – Malaysia

Reuse of a modular launching gantry for the free-cantilever erection

of the segments of a major viaduct

▲ VSL adapted its modular launching gantry to carry out the segment erection.

▲ Falsework was used in erecting the

end spans.

www.vsl.com

Edited

2012

ID 2

55

7

OWNER

Malaysia’s public works department

ENGINEER

Maunsell, Sharma & Zakaria (MSZ)

MAIN CONTRACTOR

Ahmed Zaki Sdn. Bhd (ASZSB)

VSL ENTITY

VSL Malaysia in JV with Projalma

DATE

2006

This ensured that the gantry loads

could be transferred to the

crosshead.

For the post-tensioning, VSL

supplied and installed approximately

1,100t of internal and external

tendons, as well as providing

specific cast-in components for

incorporation into the segments.

Segment erection works covered

the design and supply of the

launching girder, the falsework to

support out of balance part of side

spans and provision of all labour

and supervision for the launching

girder operation and the falsework

installation and dismantling.

VSL was also responsible for all

aspects of the construction

engineering, including the design

of temporary stressing for segment

erection, pre-camber and

alignment calculations, preparation

of the erection kinematics and

calculation of the stressing

elongation for the post-tensioning

tendons.

▲ Casting of segments in Projalma's casting yard approximately 200km from the site.

▲ The segments had to be carefully

prepared for transport.

▲ Deck access at pier locations

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