Progress of the tunnelling market in South East Asia is solid, and creatively so. Though not able to command the vast resources of China, building beyond-grand underground solutions to its problems, seen particularly in the Yellow River diversion project, or the sheer scale of India’s infrastructure and hydropower ambitions, South East Asia is still rolling out a number of large-scale projects, with enough new records and ‘first uses of’ to steal the limelight away from the neighbouring behemoths.

Project and national trends

Large-scale projects are more limited in Malaysia. The recently completed 9.7km Kuala Lumpur Stormwater Management and Road Tunnel (SMART) and the major Pahang-Selangor Water Transfer Tunnel (see below) are two key projects. Both relate to water management. There has been ecological concern over the Pahang-Selangor tunnel in particular relating to deforestation.

Hong Kong
The Hong Kong Special Administrative Region boasts some of the most interesting and impressive projects in South East Asia, several of which are listed below. These range from grand flood-defence schemes to a record-breaking bridge-tunnel that dives to the ocean floor through an artificial island. Unfortunately one of these projects in particular, the express rail link (below), has resulted in anger from several groups in Hong Kong over environmental impact, as well as the accusation that it is the decision of a rich, elite minority. The dispute saw the Legislative Council Building of Hong Kong besieged by protestors in January 2010.

With the now completed Circle Line project and the ongoing Downtown Lines (DTL) of Singapore (see below), the zeitgeist is clearly in metro works. Indeed, the Land Transport Authority (LTA) of Singapore has set a 2020 target for doubling the nation’s metro network to 278km. Despite this, there is variety and scope in the Singaporean market to rival that in Hong Kong. Listed below are some ongoing key projects ranging from hydrocarbon bulk storage to water supply.

The local tunnelling society, the Tunnelling and Underground Construction Society of Singapore (TUCSS) has bid to be the host nation for the World Tunnel Congress (WTC) 2014, Leslie Pakianathan, chief resident engineer with Mott MacDonald as well as an ICE and TUCSS member, tells T&TI. With all of the work that is happening in this hub of South East Asia tunnelling activity, it is a strong bid and, if chosen, is likely to be well-attended.

Although there are a dizzying variety of projects underway in South East Asia, some trends have emerged. Vietnam, like India, is getting into hydropower in a big way. Vietnamese heavy construction contractor Cavico is scooping up the majority of hydroelectric tunnelling work in the country.

Pick of the projects

Pahang-Selangor water transfer tunnel
The Malaysian Ministry of Energy, Green Technology and Water is investing in underground solutions to provide drinking water to a growing population. This project, running for an exhaustive 44.6km at 5.2m in diameter will provide for the needs of 7.2M people by 2013 in Selangor, Kuala Lumpur and Putrajaya, where water shortage is expected after 2012. Dealing with the hard, abrasive granitic rock of the Titiwangsa mountain range, wireless cutter monitoring is of paramount importance to the SNUI JV of Shimizu, Nishimatsu, UEM Builders and IJM Construction. The three TBMs were assembled by their respective adits and then carefully brought down the six to 10 per cent grade slopes to the NAT-Mexcavated launch tunnels.

Excavation of the MYR 9bn (USD 2.98bn) project will complete in 2014.

Hong Kong-Zuhai-Macau bridge-tunnel
A 6.7km, 37.95m wide immersed tube tunnel, the world’s longest, will form part of the 29.6km link between the three Chinese islands. An immense engineering challenge, the China Communications Construction Company will connect the tunnel and elevated bridge through artificial islands.

“Since the artificial islands and tunnel will be constructed in sea environment, it is anticipated that the technical difficulties and challenges will be of world-class level,” says a spokesman for the Hong Kong Highways Department. “This takes into account the long distance ventilation and safety design, prefabrication and marine transportation of huge pipe segments, joining pipe segments under high water pressure as well as construction of the west and east artificial islands.”

Early estimates place the total construction cost at USD 9bn.

Guangzhou-Shenzhen-Hong Kong Express Rail Link (XRL) tunnel
The 142km XRL includes a total of around 26km of underground track through six sections of tunnels ranging from 2.0-7.6km along the route from the new West Kowloon terminus in Hong Kong to Huanggang. Designed by Arup and Atkins, much of the tunnelling work was awarded to Leighton Asia, local subsidiary of Leighton Holdings. Hong Kong MTR and the Hong Kong Institute of Environmental Impact Assessment (HKIEIA), aided by consultant AECOM, identified the technical necessity for the consideration of unknown ground conditions along the alignment, specifically the avoidance of soft ground and the associated safety and building settlement issues. The line will be opened in phases between 2011 and 2016.

Tsuen Wan Drainage Tunnel
The 5.1km, 6.5m id single drive tunnel and three intake structures were designed by Mott MacDonald and will intercept excess stormwater to protect Hong Kong from flooding. Running 100-200m below ground, it is designed to cope with a once-in-200-years storm. Ecological requirements presented a challenge and the drain was created to only intercept water flows caused by rainfall exceeding 30mm per hour. Spiral ramp structures are being built in the shafts.

“The Slope on the spirals is gentle so the water runs down into the tunnel in a smooth, controlled stream,” says Sidney Lui, Mott MacDonald project manager. “That prevents pockets of air from being forced into the tunnel, which could cause water back up, and overtop the channels.”

The tunnelling contract was valued at HKD 1.12bn (USD 144.17M).

Hong Kong West Drainage Tunnel
The ‘longest drain in Hong Kong’ achieved breakthrough in February. The 10.5-km, 6.25 to 7.25m-diameter tunnel project involved the first use, in Hong Kong, of raiseboring and reverse circulation to construct dropshafts, of which there are 32, as well as 34 intakes. The raiseboring method was employed to reduce disturbance at the surface. The main tunnel was excavated by two TBMs, with horizontal adits by drill and blast.

Like the Tsuen Wan Drainage Tunnel, it will protect Hong Kong from stormwater surges and flooding.

The project cost total is around HKD 3bn (USD 385.4M) and construction should finally complete in late 2011.

Downtown Line (DTL)
The driverless DTL metro of Singapore will serve half a million passengers daily and run for over 40km when completed in 2016. Broken up into three phases, tunnelling on the first has already been completed. The third stage alone requires 28 TBMs according to Ow Chun Nam, president of the TUCSS. “The entire DTL is expected to become operational in 2018,” says Chun Nam, president of TUCSS.

Herrenknecht, which is supplying 10 of the 19 TBMs for the DTL 2 project tells T&TI: “Mixed ground conditions pose different problems and challenges. To avoid clogging while still being able to break the hard Bukit Timah granite, we designed a cutting wheel equipped with heavy duty disc cutters and more gauge cutters in order to perform optimally in the variable ground conditions.”

In addition to this, eight of the machines are fitted with double-chamber airlocks in order to reduce downtime during the regular cutterhead intervention and cutter tool changes.

Jurong Cavern
The first underground hydrocarbon bulk storage facility in South East Asia is being constructed in Jurong Island, Singapore. The contract was awarded to Hyundai E&C in 2009 for 8km-long tunnels and five caverns from the two completed access shafts. Each cavern is made up of two storage galleries of 20m(W) x 27m(H) x 340m(L). The overall storage capacity is approximately 1.47M cubic metres. Phase one of this project should be completed by 2014.

Newater Infrastructure Plan Transmission Mains Extension
“The Public Utilities Board (PUB) is undertaking a water supply programme known as the Newater Infrastructure Plan Transmission Mains Extension,” Chun Nam tells T&TI. “This project is to extend the Newater transmission network to Jurong Island, to meet the increasing demand of industries on Jurong.

“It consists of the installation of approx 5.5km of 2.2m-diameter and 9km of 1.6m-diameter Newater pipelines on the mainland and Jurong Island by surface laying and pipe jacking methods.

“The construction of an approximately 3km long, 6-metre diameter undersea tunnel, with twin 2.2m-diameter pipelines from Jurong Island to mainland Singapore forms part of this project. The contracts were awarded in 2010.”

Marina Coastal Expressway
The dual five-lane, 5km long Marina Coastal Expressway (MCE) will be the tenth expressway in Singapore when completed in 2013. It will form a key element of the strategic island-wide road network to support the long-term growth of Singapore. In January 2009, the Land Transport Authority awarded the last of six major civil construction works contracts for the MCE. Works for the MCE commenced in April 2009 following the ground breaking ceremony at Marina South.

Mott MacDonald, in a design consultancy role with construction responsibilities, says that a particular challenge comes from the need to tunnel under the seabed from the Marina Barrage, a dam that at times needs to be opened to allow water to flow out.

Sentosa Gateway Tunnel
“LTA will be building a new 1.3km two-lane road tunnel to deal with expected growth in traffic from the continued development in the Sentosa Island and Harbour Front areas,” says Chun Nam.

“The Sentosa Gateway Tunnel will complement a suite of road improvement measures that LTA announced in February 2008 to cater for the increase in traffic demand from the Resorts World development at Sentosa. Construction of the tunnel is expected to complete by end of 2015.”

One of the Herrenknecht TBMs used on the Singapore DTL project Construction site for first TBM launch on the Singapore DTL phase two Map of Singapore showing main railway network and geology