OPERATIONAL SEQUENCEDESIGN

We provided the detailed design of a Cantilever Bridge (CLB) that

was designed for the construction of a 2450 meter long LNG jetty.

The CLB consists of two 1.8 meter high box beams that form the

backbone, on top of the box beams crane tracks are provided for

two gantry cranes and a crawler crane with a custom carriage.

Furthermore, piling templates, work platforms, storage platforms,

and all other required equipment is attached to the backbone.

The jetty consists of steel support piles, concrete headstocks sup-

porting roadway elements and LNG-pipe racks which were posi-

tioned next to the roadway. All these elements were placed by the

Cantilever Bridge.

After successful completion of the first CLB, TWD modified the

exsiting design and developed a second CLB for the Ichthys and

Wheatstone LNG jetties in Australia. To improve performance and

to adhere to the strict Australian safety requirements, the focus

of these design projects was on optimizing the operational work-

ing sequences, remote operability of platforms, and safe access

design.

The whole structure was launched forwards after which the canti-

levered part was supported by temporary spud units. New foun-

dation piles for the next head stock were driven using its front pil-

ing template, and with a second template suspended on its side,

the foundations for the headstock extensions were driven. After

completion of the new head stock, the spud units were retracted,

roller supports were placed, and the CLB was shifted forward to

the next headstock location.

CANTILEVER AND FINISHING BRIDGE WWW.TWD.NL

CANTILEVER AND FINISHING BRIDGE

PROJECT HIGHLIGHTS

ONE SOLUTION TO BUILD A JETTY STARTING ON LAND,

CONTINUING THROUGH A MANGROVE, ENDING IN WA-

TER DEEP ENOUGH TO MOOR LNG TANKERS

JETTY BUILDING MACHINE FULLY EQUIPED WITH ALL

REQUIRED TOOLS AND ACCESS PLATFORMS

ACCOMODATING NUMEROUS BUILDING PROCESSES

WITHIN A LIMITED AMOUNT OF SPACE

2450m LONG JETTY WAS BUILT WITH AN AVERAGE

SPEED OF THREE SPANS PER WEEK

CANTILEVER SPAN OF 24m

Launching girder

DESIGN CHALLENGES

TWD designed one solution to build a jetty starting on land, con-

tinuing through a mangrove, and ending in shallow to deep water.

All construction works were performed by the CLB, ranging from

pile driving with two sets of templates, providing access for weld-

ing of headstocks, and placing the pre-cast roadway elements

with the gantry cranes. All works could be carried out from the

CLB, fitting in a limited available space. Different structures were

designed to provide access to difficult to reach welding areas.

CANTILEVER AND FINISHING BRIDGE WWW.TWD.NL

TEMPORARY WORKS DESIGN

T

W

E

+31 10 294 03 74

www.twd.nl

info@twd.nl

Rotterdam Science Tower - Marconistraat 16

3029 AK Rotterdam

The Netherlands

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LAUNCHING GIRDERThe launching girder was designed to install pipe racks on the

headstock extensions. The girder was pulled forward using a sep-

arate winch system, which was hooked on a headstock. Hydraulic

skidding systems were designed to be able to accurately position

the piperacks.

Platform suspended on headstock extension

FINISHING BRIDGEThe CLB was followed directly by the Finishing Bridge, a second

skidding system that took care of all jobs that were not time criti-

cal. The finishing bridge could move back and forth using an inter-

nal capstan winch and a hook-on system to pull on the installed

headstocks, and thereby launching itself forwards.

ACCESS PLATFORMSSeveral types of access platforms were designed to reach the pile

below the headstock. At the front the platforms were clamped

around the pile using friction. The platforms on headstock exten-

sions were suspended from the headstock itself.