Members of the Marina Bay project team. (Photo: Justin Ong, The Institution of Engineers, Singapore)
Marina Bay has enshrined Singapore as a global city. While its spanking new buildings are what come to mind at the mention of its name, much work took place behind the scenes during the development of the premier district.
The Urban Redevelopment Authority played a key role in transforming Marina Bay from a vacant piece of land into the world-class destination it is today. Not only did it plan and guide how land should be used, the agency also implemented and coordinated the essential infrastructure needed to support developments there.
URA worked closely with public and private sector partners and engineers over a span of 20 years to build them. Several projects were new to Singapore, such as the 5.7km Common Services Tunnel (CST) linked to electrical substation which provides key underground utility connections to properties within the area. The CST houses telecom cables, power lines, and chilled water, potable water and pneumatic refuse collection pipes.
The CST, which is as big as two MRT tunnels, houses telecom cables, power lines, and water and pneumatic refuse collection pipes.
Other “firsts" include the iconic Helix and Jubilee bridges, and the barrier-free waterfront promenade around Marina Bay. These projects and the CST were integral in the vision to transform Marina Bay into a financial centre, civic space, and community playground.
In 2004, work went full steam ahead on several major developments that were on a tight deadline to realise that vision. “At the height of the building schedule, there were many public and private developments competing for construction access at the same time,” recalls Ler Seng Ann, URA’s group director of development services. “The effort to coordinate and ensure that work on all projects went ahead smoothly was a great challenge."
But over and above the din of new residential and office towers rising in the skyline, Ler and colleague Loo Pak Chai, the director of project management and specialist head of the project, were busy putting together the city centre’s infrastructure backbone. Loo calls the CST the Marina Bay’s engine, a sophisticated piece of engineering that is efficient in delivering utility services to buildings in the precinct.
But constructing the CST as big as two MRT tunnels below ground had immense engineering challenges. There were pier and wharf structures buried under reclaimed land, and some parts of the tunnel had to cut below existing MRT lines.
The trickiest was a buried 1.7km-long, up to 25m deep, 50m-wide, rock-solid breakwater from colonial times that was in its way. “This was the most difficult of the many challenges we faced,” says Ler. “We could not remove it like other seawalls which were easily broken. Some of the stones weighed as much as 20 tonnes each. So we built structures called cofferdams around parts of the breakwater to take them out.”
Walls dating back to colonial times and buried up to 20m deep had to be removed for the development of the CST.
The engineering team constructed a cofferdam filled with seawater, which was the best and cost-effective way to carry out the “underwater excavation” work. A global positioning system then guided a crane operator who used a clam-shell attachment to remove the rocks.
The first phase of the CST network was completed within five years. Digging up roads – a common method to repair and maintain utility cables and pipes – is now a thing of the past at Marina Bay. Such work is instead carried out inside tunnels, without any disruption to traffic. And as utility cables and pipes are housed in the CST’s concrete structure, they are also protected from accidental damage should any excavation work take place on the roads above.
URA’s other vision was to give pedestrians a safe and obstacle-free stroll along the waterfront promenade and bridges around the Marina Bay. The objective was to provide a necklace of attractions around the bay district with pedestrian-friendly bridges and a promenade. In linking Marina South and Marina Centre, engineers built the Helix Bridge in the shape of a DNA that symbolises life and continuity, renewal and growth.
State-of-the-art utility infrastructure in place at Marina Bay.
“It was a unique and complex design, and there was no reference point for us on how to make it simple enough to construct and install,” says Loo. “It was built offsite, segment by segment, and the spiral tubes were bent manually until we reached a level of accuracy that each connecting piece achieved the right 3D coordinates. It was then dismantled and reassembled onsite.
The Jubilee Bridge was also planned as a barrier-free link between two important landmarks, the Esplanade Theatre and the Merlion. At 220m long and 6m wide, it can hold up to 2,000 people, but building it brought about its own set of challenges. URA engineers wanted minimum disruption to public access between the two points, and to businesses and water taxis plying the river during construction.
Cofferdams were used to create a dry area in the middle of the river to lay the foundation for the bridge and erect a central column on pile caps. Segments of the bridge, fabricated offsite and brought in on barges, were then installed on the column, one at a time in each direction, in the cantilever method to maintain it in a balance state until each one was in place.
“In this project, we decided to put the pile caps underneath the riverbed to allow a wider channel flow and to achieve a better slender column appearance, although it made the construction process difficult,” explains Loo. “The final product is a simple and elegant bridge.”
In transforming Marina Bay from a vacant piece of land into a world-class destination, URA worked closely with public and private sector partners.
While there were many challenges in building Marina Bay’s backbone, putting it in place has set Singapore apart from other cities, and delivered big gains for the developments it serves. The Marina Bay has often been cited as having one of the most eye-catching skylines in the world. It would have remained just a vision had it not been for engineers who turned it into reality and made it functional for everyone to experience it fully.
This article first appeared in the book "Engineering a First World – 50 Feats That Transformed Singapore", by the Institution of Engineers, Singapore (IES). The book, priced at $48, can be purchased from IES via email or phone at 6461 1246.