East Coast Line Construction: Constructing Katong Park

Along with the formal announcement of Founders' Memorial station, the Land Transport Authority yesterday also provided an update on the construction of the Thomson-East Coast Line (TEL). In particular, a more in-depth look at the construction of Katong Park station was provided.

We understand that the Katong Park station will be of a stacked configuration whereby the upper platform level is shared with the concourse, similar to Stevens station on the Downtown Line. However, unlike Stevens station, passengers will be able to switch between platform levels without the need for tapping out of the system.

A 3-dimensional model of the Katong Park station showing the upper platform & concourse level.
Faregates are visible at both ends of the station.

According to LTA, excavation of the station could not progress until the tunnels for the station had been bored through. Tunneling from contract T305 involves launching the tunnel boring machines (TBMs) from a launch shaft abutting contract T303 near the Singapore Swimming Club, in the vicinity of the Kallang-Paya Lebar Expressway crossing. The TBMs will make their way from the launch shaft, through Katong Park station and emerge at Tanjong Katong (formerly named Amber) station where they will be dismantled.

Typically, when boring stacked tunnels, the lower tunnel is mined first followed by the upper tunnel. When approaching a station, the tunnel breaks through a portion of the retaining wall. If the station is at a sufficiently advanced stage of construction, the TBM can be pulled or pushed across the track bed at platform level to commence tunneling from the other end of the station.

Occasionally, station construction is not this advanced, particularly in tight sites where the top-down construction method is used. This would require the TBM to continue tunneling through the station box even after breaking through the retaining wall. The tunnel rings used during this portion of the drive may be concrete rings that are demolished subsequently or steel rings that are used to retain the shape of the tunnel. Such a technique was formerly used on the Circle Line during the construction of Buona Vista station, where the TBM tunneled through the station box and the temporary rings were later removed as station excavation progressed down.

The below video shows the launching of the TBM from the launch shaft along Tanjong Rhu Road in September 2017.

As both the upper TBM boring the Changi-bound tunnel and the lower TBM boring the Woodlands-bound tunnel have passed through the station box, they should be well on their way to Tanjong Katong station for their final breakthrough. As the distance for this portion of the drive is about twice a long, it can be expected that the duration of tunneling would take twice as long as well.

Below are some renders of the Katong Park station, showing the entrances and platform levels with natural sunlight filtering in.