Central Expressway

Central Expressway (CTE) connects the Seletar Expressway (SLE) at its junction with the Tampines Expressway (TPE) in the north to the Ayer Rajah Expressway (AYE) in the south near its junction with the East Coast Parkway (ECP). It links the north and the south of Singapore through the Central Business District (CBD). Constructed in two phases, the CTE opened in 1991. Portions of the road are laid underground and these parts of the CTE form the first underground highways of Singapore.

History
The CTE, a 16 km expressway, was constructed at a total cost of S$500 million. It was built in two phases with different stages that involved a total of eleven parts or sections of construction. The laying of the 12.5 km stretch of road from Yio Chu Kang to Bukit Timah Road formed phase one of the construction, which was completed in the 1980s. The portion of expressway between Yio Chu Kang and Ang Mo Kio Avenue 5 was officially opened on 17 June 1989 by the Member of Parliament for Cheng San GRC, Heng Chiang Meng. The construction of this 1.7 km three-lane carriageway stretch of the expressway was delayed by almost two years due to resettlement problems when residents in the area had to be moved. The first phase of the expressway construction also included the building of the Whampoa flyover connecting the Pan-Island Expressway (PIE) and CTE.

The Public Works Department began accepting tenders for the construction of the 3.7 km phase two of the CTE in April 1986. Dubbed the city portion project of CTE, PWD engineers took more than two years in finalising the plan for this phase before requesting for tenders. It was not only touted as the single most expensive road project of Singapore at that time because of the construction of two underground tunnel ways, but was also considered a complicated and difficult road to lay because of its design. From more than ten civil engineering firms that pre-qualified for the job and eight short-listed candidates, contracts for the construction of various jobs in this phase were awarded to a group comprising of the firms, Bocotra Construction, Lee Kim Tah, Metrobilt and Wang Coo Kien. Construction of the road commenced on 25 January 1988 and excavation work for the underground tunnels began in June 1988. The government acquired nearly 54,000 sq m of land around the areas of Orchard Road, Cavenagh Road and Clemenceau Avenue for the project, after first earmarking the areas in 1986. The total cost of the phase two of the construction was S$350 million.

As a part of the 1990's PIE widening project, the Whampoa flyover was improved to become the only four-way junction for intersecting expressways in Singapore. On completion of the improvement work, this flyover was officially opened by Acting National Development Minister Lim Hng Kiang on 29 October 1994.

Underground tunnels
Of the total 3.7 km of CTE from Bukit Timah Road to Chin Swee Road, only about 1.3 km of the expressway form the surface roads, including parts of which were constructed below existing road levels. The rest of the expressway is laid underground. There are two tunnels: north and south. The north tunnel is a 41 m wide, 700 m stretch of road from the junction of Bukit Timah and Cavenagh Road to the junction of Clemenceau Avenue and Cairnhill Circle. This portion of the expressway is divided into northern and southern carriageways with four lanes each. An interchange was built at Clemenceau avenue to allow motorists to have access to Orchard Road by driving off the CTE up Cairnhill Circle and into Orchard Road. Due to the existence of the interchange, both Cairnhill Circle and Bideford Road were converted into one-way lanes on completion of the construction of the CTE.

The south tunnel extends from under the Meridien Orchard Hotel in Orchard Road to Chin Swee Road. Measuring a total of 1.7 km, it passes below Penang Road, Singapore River and Havelock Road. It has three lanes on its either side. The portion of the tunnel under water is near the Clemenceau Bridge over the Singapore River. At this point the expressway lies two metres under the Singapore River. Stones were laid over the river bed to prevent the river from eroding to the tunnel level. This section of the expressway took almost two years to build as the river had to be dammed in stages during the construction. The south tunnel was considered the toughest part of the entire CTE to build because of its tricky layout. A portion of the expressway even cuts across an MRT tunnel between Somerset and Dhoby Ghaut MRT stations. It also cuts across the Stamford Canal near the Kramat Lane. A three storey interchange, with five slip tunnels, links the expressway with some of the surface roads here such as the Merchant Road, Havelock Road and Upper Cross Street.

Construction work
Because of a variety of soils along the route, more than six different types of temporary retaining walls were put up during the excavation and tunnel building work. As the diameter of the tunnels are around three to four times of MRT tunnels, their large size made it necessary to use the cut-and-cover method for most part of their construction, instead of the boring method used in the building of the MRT tunnels. Traffic was diverted along the excavation sites resulting in the loss of two to three lanes along major traffic routes. Instruments were attached to around 40 buildings that came within 50 m of the excavation sites to monitor noise and vibration levels. Some of the buildings in this category include Meridien Orchard Hotel, Landmark Tower, Thong Chai Building, Central Building, Liang Court, Singapore Shopping Centre, Glass Tower and some HDB housing units. Around 440,000 cu m or 70,300 truckloads of concrete was used for the entire second phase of the construction.

The construction of the last section of the CTE was completed in April 1991. A mass walk-and-jog event was held on 15 September 1991 for people to familiarise themselves with the tunnels a week before the official opening of the CTE. More than 10,000 turned up for the event, which was a seven km route covering both tunnels and their surface connections. The event was flagged off by the Senior Parliamentary Secretary for National Development Lee Yiok Seng. The official opening ceremony of the CTE's second phase took place on 21 September 1991. The tunnels were opened to traffic at 6 pm and about 50 vintage cars, led the procession with the Senior Minister of State Tay Eng Soon at its head in a 1935 BMW. They became the first motorists to use this portion of the CTE.

Description
The concrete roof of the tunnels are 1.5 m thick. The shallowest part of the tunnel is 1.5 m below the ground while the deepest part of the tunnel is five to six metres below the ground. Fire protection, emergency power supply systems, hi-tech gadgetry to ensure safety and sophisticated traffic surveillance and control, all add up to the maintenance cost of four to five million dollars for the tunnels annually. Detectors have also been installed to warn of congestion should lanes close for reasons such as a traffic accident. Ventilation is automatically adjusted according to the volume of the traffic. Lighting in the tunnels is automatically adjusted too. Staircases leading to the ground level are located at every 200 m interval. Closed-circuit television cameras are installed every 100 m while hydrants, hose reels and fire extinguishers are located at every 50 m interval. Everything in the tunnel is monitored from the computerised 24 hours tunnel control centre.

Significant construction along the CTE include private and HDB housing units, the Ang Mo Kio ITE, Da Qiao Primary School, Singapore Cheshire Home and Serangoon Garden Estate. The Chong Li Primary School and Chong Boon Secondary School are located in a common compound near the Ang Mo Kio Central Flyover Park at the junction of Ang Mo Kio Avenue 3 and the CTE. Significant construction along the expressway also includes the Ang Mo Kio Industrial Park, Construction Industry Training Institute, Toh Payoh Industrial Park, Volkswagen Golf Centre, St. Andrew's Secondary School with the Chapel of the Holy Spirit next to it, St. Wilfred Field, Bendemeer Secondary School, ITE Balestier and the Seventh Day Adventist Church with the Eye Hospital next to it. The CTE runs below a number of popular landmarks in the CBD, such as the Istana Park. Vehicular bridges have been constructed over the Kallang River and Sungei Whampoa.



Author
Naidu Ratnala Thulaja



References 
Bidding date for Central Expressway extended. (1987, May 20). The Straits Times.

Central expressway project progressing well despite problems. (1989, June 2). The Business Times, p. 1.

CTE project completed. (1991, May 11). The Straits Times, p. 22.

CTE project uses 5,000 truckloads of concrete each month (1989, December 16). The Straits Times, p. 24.

CTE stretch at Ang Mo Kio now open. (1989, June 18). The Straits Times, p. 16.

Dhaliwal. R. (1988, September 28). Work starts on Central Expressway tunnels. The Straits Times. p. 18.

Dhaliwal, R. (1989, February 25). Move to speed up work on the CTE . The Straits Times, p. 24.

Inside Singapore's massive road project. (1988, March 04). New Straits Times, p. 14.

Lee, H. S. (1988, March 02). Work starts soon on underground highway. The Business Times, p. 18.

Kumar, S. (1991, January 04). CTE tunnels ready before year's end. The Business Times, p. 24.

10,000 throng CTE tunnel for jog and walk. (1991, September 16). The Straits Times, p. 1.

Pereira, M. (1989, January 09). CTE at 'critical stage' as excavation work starts. The Straits Times. p. 13.

Underground CTE to open on Sept 21. (1991, August 8). The Straits Times, p. 1.

Vintage cars in drive for funds to be first to use tunnels. (1991, September 20). The Straits Times, p. 26.

Work begins to put finishing touches to some parts of CTE. (1990, June 2). The Straits Times, p. 22. 

Work on CTE tunnel roads begins. (1988, July 18). The Business Times, p. 20.

Work on the Central Expressway Phase 2. (1989, September 1). The Business Times, p. 2.

Yap, M. (1986, April 18). Tenders open for phase two of CTE. The Straits Times.

Bachy Soletanche Singapore Pte Ltd. (n.d.). 2000 - CTE/Braddell Road Interchange diaphragm wall. Retrieved December 16, 2003, from www.bachy-soletanche.com.sg/bss-thumbs/055-braddell/BSS-055-BraddellRd.htm



The information in this article is valid as at 2003 and correct as far as we can ascertain from our sources. It is not intended to be an exhaustive or complete history of the subject. Please contact the Library for further reading materials on the topic.

Subject
Commerce and Industry>>Transportation
Express highways--Singapore
Science and technology>>Engineering>>Transportation engineering



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