As one of the longest road bridges in the world, the Hong Kong Zhuhai bridge (HKZMB) represented one of civil engineering’s most challenging construction projects.

The multi-million-pound project, first suggested in 1983, spans 29 km – making it one of the world’s longest bridges. The ease of movement provided by the bridge is expected to encourage a deeper economic integration between Hong Kong and China. It will also improve access to global markets, enhance the flow of labour and goods, and strengthen the area’s growing tourist industry. RMD Kwikform was involved in this complex but inspiring road and bridge construction project.

Our involvement began in 2014, having previously supported major works for the land phase of the bridge which connects Hong Kong to China across the Pearl River.

The HKZMB will establish a new transport link between Hong Kong, Macao and Zhuhai, towards the Western Pearl River Delta, becoming one of the world’s longest bridges.

For this phase of the project, RMD Kwikform supplied a range of formwork and shoring solutions, including its heavy-duty Megashor shoring to support the construction of the turnaround facilities in the water, over the marine viaducts.

Composed of different concrete elements, the formwork and shoring solutions required to support the construction of the whole turnaround structure were both complex and varied. The first main challenge was to design support structures for the placement of two precast segments on pier (SOP) base slabs. This was followed by formwork and shoring for two sets of in-situ cast side and end walls, and top and wing slabs, completed using shoring mounted on steel beams to cast the final in-situ decks.

To form an elevated road across the existing new bridges, further support was required to place four precast girders, four precast I-beams and four precast corner beams. Once these main precast sections were installed, shoring solutions were designed to cast the elevated bridge decks and key connection segments to the main precast slabs.

With two sets of SOPs required in total, each set needed to be complete simultaneously in just four months for this section of the project to stay on programme. To achieve this we worked with the DCV JV team to plan the construction sequence of the project, in line with the lift capacity of the barge crane.

Commenting on the construction sequence and the design of the formwork solution, RMD Kwikform Deputy Sales manager, Martin Chan, said: “The turnaround facility is located in the Western Waters of Hong Kong and spans over the top of the main dual three-lane bridge. This meant the overall structure had to be built using both deck-mounted and barge-mounted cranes.

“In order to cope with the loads from the precast sections and the additional Hong Kong typhoon wind loads, we designed solutions based on our modular Megashor heavy-duty shoring system. With a requirement to support the turnaround facility from the top of the cast-in-situ pier, we designed two identical Megashor tower arrangements, each side of the main bridge, reaching a height of just over 19 metres.

“Positioned on top of cast-in-situ pile caps, each matching tower arrangement was pre-assembled in two blocks on a large barge and lifted into place, using its deck-mounted crane. To complete the 19-metre height, two types of steel spreader beams were connected to the tower, which in turn supported the main primary beams.

“The bottom half of the tower, measuring 6.7 metres long by 6.3 metres wide by 7.7 metres high, was made up of four sets of nine Megashor legs, connected together with steel SuperSlim soldiers and bar bracing. This base section was a pretty standard heavy-duty tower setup, supporting what was a much more complex second section comprised of a main tower and Megashor raker frame arrangement.

“This upper section was designed to have a total span of 16.9 metres to support the spreader beam and in-turn the SOP precast base slab. In order to achieve this, the block was made up of a 6.7 metre-long by 6.3 metre-wide six-leg inner tower, together with outer raker frames.

Martin continues: Once the main support structure was in place, the precast SOP base slab was lowered onto the primary beams and stitched into the pier. The site team then used standard formwork, including Aluminium Alform beams, Superslim Soldiers and GTX beams to cast-in-situ the SOP sidewall, end wall, top slab and wing slab. At the same time as these sections were being cast, the site team was erecting two Megashor support towers on the deck of the main bridge structure used to support the other end of the main precast girder.

“The frames themselves were made up of three Megashor legs connected together with steel SuperSlim soldiers, combined with Slimshor jacks to create the braces between the raker frames and main towers, in order to form the angle required to achieve the large span off each side of the tower.