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A 400t floating gantry similar to those used on four previous LAMA projects was designed to handle and place the precast units.

12.4.1. Hull

Two identical barges measuring 120’ x 40’ x 8’ overall were hired from Lee Trading at a monthly cost of MYR 12 000 each and prepared to be configured in a catamaran arrangement with 14.2m clearance between them. The hulls were inspected and surveyed by an independent party. Bollards and bitts were repaired and fendering was supplied and fitted.

12.4.2. Superstructure

After an exhaustive tender adjudication process a tubular steel structure of overall dimensions 21.9 x 16.5 x 16.5m was fabricated locally over a two month period and launched and secured onto the barges via the fabricator’s loadout facility. The superstructure was designed to support the load of a suspended culvert unit as well as withstand the forces generated as the two hulls moved under load in a swell in any combination of six differential actions.

Leighton-LAMA Joint Venture Section 12: Page 5 of 8 A separate walkway added to the stern sections provided no additional stiffness to the craft. A removable tie beam connected by 50mm diameter Macalloy post tensioning bars was incorporated on the forward section of the superstructure allowing the craft to approach and straddle a unit on the loadout jetty in all tide conditions.

Final superstructure steel tonnages and costs were agreed with Torsco as follows:

Main structural steel: 70.613t @ MYR 5 000 MYR 353 065 Walkways and ladders: 3.840t @ MYR 3 840 MYR 26 496 Pad eyes and gussets: 3.980t @ MYR 9 900 MYR 39 402 Erection of total steel: 78.433t @ MYR 1 250 MYR 98 041 Extras (walkway beams, additional padeyes etc) MYR 19 758 Total cost to supply, fabricate and erect MYR 536 762

The detailing particularly of the ladders and walkways was not accepted by the fabricators as being included in their works so an external consultant was commissioned to assist with the workload.

Most items were fitted during the construction phase at Lumut Port where it is eventually inspected and certified sea worthy. The barge was towed to the Manjung Power Station construction site upon completion and the balance of the installations finalized.

Stringent material and weld testing was carried out in compliance with the fabricator’s quality assurance procedures. Another consultant was commissioned to follow up all aspects of the Department of Safety and Health (DOSH) involvement leading to the issuance of a certificate of compliance. This certification aspect originally overlooked almost led to major delays.

At the end of the project it was agreed with the owner of the two pontoons to take over the entire gantry structure for his disposal or use.

12.4.3. Mooring equipment

Four 10t mooring winches with manual band brakes (two with warping drums) were fabricated by Plimsoll of Singapore at approximately SGD 17 000 each and fitted to the gantry barges. Central hydraulic controls were installed and plumbing connected to the main hydraulic power unit (HPU.)

Four roller fairleads were fabricated and installed by Lee Trading who also manufactured four new 2t delta flipper anchors. 300m of 24mm diameter IWRC mooring wire rope was fitted to each of the mooring winches.

12.4.4. Lifting equipment

Two 25t hoist winches with spooling gears and failsafe brakes were built by Plimsoll and purchased with central controls at approximately SGD 79 000 each and installed, one on each hull. Winch plinths were fabricated and welded to the deck and a non-shrink grout was cast under the foundation beams to spread the load evenly into the barge deck. Initial problems with the spooling gear developed but were remedied by replacing the drive chain sprockets.

Two 350m lengths of 36mm diameter SWR were fitted to the hoist winches and fed through single sheave deflector blocks anchored at deck level before going up into

Leighton-LAMA Joint Venture Section 12: Page 6 of 8 the hoist rigging. Two pairs of 200t SWL 5-shea ve hoist blocks supplied by Plimsoll at approximately SGD 20 000 per pair were fitted to the superstructure and each reeved into 10:1 arrangements. Theoretical lifting capacity was therefore 2 x 10 x 25 = 500t.

Two lifting spreader beams fabricated by Besteel Berhad in KL for a total of MYR 64 000 were suspended via four doubled 64mm SWR slings to the lower hoist blocks. Each beam housed two lengths of 75mm diameter Macalloy post tensioning bar from McCalls Special Products in Dubai, which connected the lifting equipment to the corbels of the precast culvert units through bearing plates, spherical nuts and washers. The lifting beams had to undergo similar DOSH inspection and certification processes as for the superstructure.

Two 8” bore diameter hydrau lic cylinder delivering 50t tension load over a stroke of 1.8m were purchased at MYR 8 000 each and supported below each of the two lifting beams. 32mm Herc Alloy reeving chain connected to either end of the cylinders ran through horizontal holes in the p recast units’ corbels and was used to pulled the units together by bearing against large locking plates.

Rope brakes were installed to ensure that sufficient tension was applied to the slack hoist wire when spooling back onto the winch drums after placing a unit. The brakes comprised lengths of hardwood timber held in steel channel frames sandwiching the rope by adjustable pressure delivered by 2½” bore hydraulic cylinders.

A number of load sensing devices were considered but they were all a bit expensive. DOSH conceded that load sensing or limiting devices would not be essential as long as the floating gantry was physically unable to lift more than the rated load.

A load test to 125% of the working load was done and attended by the relevant authorities. The 500t test weight was made up of a 400t precast unit loaded above with 100t of additional block kentledge.

12.4.5. Hydraulic Circuitry

A 180 kW (2 x 90 kW) HPU was built and supplied by Plimsoll at SGD 55 000. This provided all the hydraulic power for the two hoist winches, four mooring winches, two unit installation cylinders and the two hoist rope brakes.

Mannesmann Rexroth did hydraulic plumbing, pre-pickling, flushing, testing and commissioning of both the floating gantry and crane barge at a total cost of MYR 127 000. Some minor problems occurred after initial usage and were remedied fairly quickly. As production improved and utilization of the hydraulic equipment intensified, a hydraulic cooling system was deemed necessary and installed.

12.4.6. Other De ck Equipment and Hydraulic Circuitry

A 200 kVA generator was hired and fitted to the floating gantry mainly to provide electrical power to the 180 kW HPU. A distribution board was provided and electrical circuitry provided for deck lighting as well as domestic lighting and power.

An air-conditioned container was provided for the control cabin and another container supplied for the store.

Leighton-LAMA Joint Venture Section 12: Page 7 of 8 12.5. STONE SPREADER SUPPORT / CRANE BARGE

12.5.1. Barge hull

A 180’ barge was hired from Lee trading for the crane barge. A minimal amount of refurbishment was required prior to the hire and a third party inspection company conducted an on hire survey to assess the condition.

12.5.2. On board equipment

The barge was fitted with six new 10 ton mooring winches purchased from Plimsoll at SGD17 000 each; four of which provided the four-point mooring and the other two were for lifting the stone spreader when it was moved from bed to bed. Four 2 ton delta flipper anchors were made by Lee trading and fitted to the ends of the 300m 24mm diameter IWRC anchor wires. Fairleads and bitts were manufactured and fitted to the barge.

A 150t crawler crane was hired from Tat Hong at MYR 40 000 mob/demob and MYR 45 000 per month. The crane had a 1m² grab for feeding the stone to the stone spreader.

A 45 kW HPU was purchased from Plimsoll for SGD 17 000 and fitted and plumbed to provide hydraulic power for the four mooring winches, two lifting winches as well as the stone spreader. Mannesmann Rexroth did hydraulic plumbing, pre-pickling, flushing, testing and commissioning of both the floating gantry and crane barge at a total cost of MYR 127 000. Heat generation problems later resulted in the need to install a heat exchanger to reduce the hydraulic oil temperature.

12.5.3. Other facilities

Side boards were erected and braced in the centre of the barge to provide a stone bin to keep a supply of spare stone on board. Containers were fitted for a control room, divers change room and a store. Lean-to shaded areas and a water tank were erected.

At a later stage when the barge was used for placing pile caps it wat fitted with a RTK DGPS positioning system.