The $850M Changi station line project comprises a spur running for just over 6km from the existing East-West line at Tanah Merah station. The first section is elevated and involves difficult work building over an existing side spur to the East-West maintenance depot.
The elevated section ends at a station within Singapore's business park area and an international exposition ground.
Expo station has been designed by Sir Norman Foster with a complex toroidal curved titanium roof and a separate 'flying saucer' dish roof over the ticket office.
The remaining 4.3km of line is underground, using cut and cover and then a 3.5km long bored tunnel to swing the line into the airport station. This is Singapore's longest bore ever, and is very sensitive because its twin bores pass directly under one of the two main international runways.
Mindful of potential problems, the Land Transport Authority pre-ordered two high grade tunnel boring machines: Lovat earth pressure balance machines with extras such as spare seals, chilled water cooling and chromium carbide facing panels to resist wear.
The £7.7M worth of machines were assigned to the winning contractor, Nishimatsu of Japan, and the first of two drives has just passed successfully under the runway.
A Hong Kong/British joint venture of Gammon and Balfour Beatty is gearing up for further trackwork on the extension tunnels, having completed much of the elevated section.