The Construction of Mega Tuas Port

We have written about Singapore Maritime Status and Why Mega Tuas Port is matters to Singapore in the previous article. You can read the article here.

By now the phase 1 Mega Tuas Port already completed installing a total of 221 caissons and set to complete the entire reclamation work by 2021  with about 2,000 workers and supervisors on site. Meanwhile, the second phase already commenced.

Mega Tuas Port is a mega port that built to receiving container vessels up to 24000 TEU with 24M water depth. It's meant by the time it starts operation, the port can receive any size of cargo vessel in the world. That is the reason why Mega Tuas Port will become the largest port in the world.

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Thus, how is Mega Tuas Port constructed?

Maritime and Port Authorities of Singapore or MPA is constructing the port by Caisson Technology. 

Caisson construction, also known as caisson foundation, is a water-retaining structure that is mainly used in construction projects that take place underwater. Caissons are prefabricated cylinders or hollow boxes that are sunk to the desired depths beneath oceans, rivers, and other water bodies. They are then filled with concrete to create a solid foundation for the project, serving as an anchor. Structures such as concrete dams and bridge piers generally require a caisson as a base. 

The technology is not new and already been used since ancient for port infrastructure construction.  For Mega Tuas Port, Caisson will be installed for the breakwater, to form the seawall for reclamation work. 

The use of caissons in Phase 1 is a safer and more efficient method of reclamation compared to traditional methods such as piling. In fact, the method will be used for the remaining 3 phases as well. The caissons used for Tuas Terminal’s construction are one of the largest in the world. Pre-fabricated onsite, the caissons each weigh 15,000 tonnes and measure 40m in length, 28m in width, and 28m in height – as tall as a 10-story building. Besides that, it is much faster than any other method to construct a port. 

Above graphic shown a methodology of how the seawall constructed to form the perimeter of the port. The perimeter watertight seawall will then break off the water from the sea and internal of the caisson wall. The reclamation of the land inside the wall will then carry out. 

To lay the caisson to form the seawall, a rock mound layer of foundation on the seabed need to be constructed. 

1. A mega dredger will dig the trench on the seabed along the caisson installation location to require the depth. The world's largest grab dredger, which has a bucket capacity of 200 cubic meters, has been deployed to help with this massive project.
2. The trench will be filled with sand by the Temarock vessel.
3. Then, the vessel will lay a layer of rock mound on the filling trench.
4. Tamarack vessel will compact the sand filled in trench with tamping arm.
5. Lastly, the trench will be filled with a smaller diameter rock mound layer, and it will be leveled up for accurate caisson installation.

“TEMAROCK is a next-generation all-in-one rock mound construction vessel. The conventional process of rock mound construction requires multiple vessels for rock laying and compaction, one survey vessel to facilitate operation, and is supported by divers. TEAM ROCK automates these tasks, eliminating the need for multiple vessels or divers’ assistance. This enhances efficiency and safety.”

On the other hand, the fabrication of the caisson will be carried out concurrently. 

For Mega Tuas Port, 2 caisson fabrication yard has been constructed side by side to fabricate 2 caisson at the same time to speed up the construction schedule. (Some other port projects do casting of the caisson on the floating dock.)

1. The caissons are cast on the yard layer by layer with each completed unit using around 1000 cubic meters of concrete. The caisson may be cast in different sizes and dimensions according to requirements. The structure averagely 28m-high concrete watertight structure. Each caisson weighs about 15,000 tons, equivalent to the weight of about 8,000 cars stacked together.
2. After the completed casting of the caisson, it will be pulled onto a caisson floating dock.
3. Then, the caissons will then be towed to the installation location with the floating dock. Caisson will then submerge so it can move freely from the dock and will be towed to the final location for installation.
4. Once the caisson on its final location, it will be ballasted with seawater to sink on the foundation.
5. The caisson will then filled in sand and concrete will be cast to form a deck solid ground layer on the caisson.

“The fabrication of caisson requires a large number of rebar sections, to coupe with the amount of volume, advance technology, Automatic Rebar Machine using Robotics System (ARMS) has been used. ARMS automates the bending and cutting of reinforcement steel bars (or rebars, which are used to strengthen concrete) to the desired design, and then transfers them onto the stacking area. The conventional practice requires workers to handle the rebar manually, which exposes them to mechanical hazards when they operate the rebar cutting and bar bending machines. “

After the caisson installed, the internal area of the caisson seawall will be reclaimed to form solid land. Subsequently, the terminal will be built with the installation of port equipment and facilities.

The project also illustrated the re-using of materials such as excavated earth from land construction projects as an eco-friendlier approach. This, MPA said, reduces the quantity of sand required for reclamation by around 70 percent for Phase 1 and 50 percent for Phase 2. MPA expects to achieve cost savings of around S$2 billion.

Here is our little sharing of how is the port will be constructed. You can see the interesting video of Phase 1 construction below.

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