Building airport of the future

9 Jul 2018

The new Terminal 4 at Singapore Changi Airport was opened to the public In October 2017. It was completed after three years of construction, comprising a two-storey terminal with a total floor area of 225,000 sq m. RSP Architects Planners & Engineers was appointed by Changi Airport Group (CAG) as Civil & Structural Consultant for the project. Here, RSP shares the challenges it faced and how the company overcame them through innovative methods.

The new Terminal 4 (T4) has a capacity of 16 million passengers per year, bringing the total annual handling capacity at Changi Airport to 82 million passengers. It is Singapore’s first airport terminal that introduces a fully automated departure process – known as FAST (Fast And Seamless Travel) – to enhance efficiency and convenience for passengers. The terminal also has a centralised departure, arrival and pre-board security screening area, which is located on the second storey.

The development of T4 was carried out in three phases, with a total construction cost of S$1.147 billion. Phase 1 took about 30 months, including the main terminal building and south finger pier; Phase 2 was completed within 34 months, comprising the north finger pier and a multi-storey car park; and Phase 3 lasted for 37 months, consisting of another multi-storey car park and the taxi holding area.

Working together with the design and build contractor - Takenaka Corporation - RSP faced several challenges throughout the project. Among them included the tight schedule of 30 months for the first phase, as well as complex roof designs to achieve a spatial and column-free environment such as the 60 m large-span roof at the departure check-in hall, 18.5 m large-span cantilever roof at the departure kerbside and massive transfer trusses at the arrival immigration hall.

Plus, there was a site constraint. The fixed gangway structures are located within airside with live aircraft parking stands, and they have to meet strict security requirements and airside operational needs.

To solve the problems, RSP adopted the DfMA (Design for Manufacture and Assembly) methodology to increase work productivity and safety on the project. BIM technology was used in the design stage to provide better-informed decisions and assess design solutions; identify construction risks before commencement of site works; and maximise site productivity and safety by minimising abortive works on site.

‘Hat-first’ method

To speed up the construction of Phase 1, the project team implemented an innovative ‘hat-first’ method for the main terminal building. The second storey and roof were completed first, then works continued on to the first storey and Mezzanine floors – starting at the centre of the building and moving outwards.

Combining the hat-first method with a middle-out approach allowed the internal finishing and M&E works to start quickly, and also enabled an early installation of the baggage handling system (BHS). This also meant that a temporary roof was not required and the works could be sheltered from the rain.

“Back in 2014 when we first started, the hat-first method was considered new in Singapore for such a massive scale project, and it required an early contractor involvement,” said Er. Lai Huen Poh, senior managing director at RSP who oversaw the T4 project. “The traditional way we build here has always been a bottom-up approach,” pointed out Er. Lai, “but it wouldn’t have helped us to finish this project on schedule.”

There were also other benefits gained from the hat-first method, added Er. Jessica Lim, director at RSP and also a key engineer in charge of the T4 project. “It allowed us to perform a multiple slab construction. Upon completion of the second storey and the roof, the team could proceed with the slab construction for the first storey, Mezzanine 1 and Mezzanine 2 at the same time.

Furthermore, precast columns could be installed directly on pile caps before the slab construction for the first storey began, continued Er. Lim. Also, because the slab concreting work for the first storey was carried out under the shade, it produced a good quality of concrete. What’s more, facade works could be completed earlier, even before the internal finishing and M&E works commenced.

 

Excerpt of article by Southeast Asia Construction. Read the full article in the Jul/Aug 2018 issue.