Thomson Line Construction: Orchard - Before the Trees Fell

Monday, 29 September 2014

Orchard - Before the Trees Fell

Contract T219 is for the construction of Orchard Station, cripple sidings and twin bored tunnels towards Orchard Boulevard. Similar to T218, the site of the contract sits on a land currently occupied by the Overseas Family School (OFS). A new campus is currently being built at Pasir Ris, and OFS is expected to move out of the Paterson campus by the middle of next year.

Orchard Station

The new station will see 4 new entry points. This includes Wheelock Place, Paterson Road and Orchard Boulevard. A new Pedestrian Overhead Bridge will connect across the Paterson Road entrance as an additional entry point too. The existing entrance B along the North South Line station will be altered and integrated into a primary entrance for the Thomson Line. The station will have 3 main basements - A concourse (same level as B1 in Ion), platform (Ion B2) and transfer level (Ion B4), and will be constructed top-down using the diaphragm wall method.

Location of 3 of the new entrances to be built around the Paterson junction

Transfer to North South Line
A simplified layout of the interchange:

B1 - TSL Concourse/ ION B1
B2 - TSL Platform/NSL Concourse/ ION B2
B3 - NSL Platform
B4 - Transfer level

As the ground level at Orchard Boulevard is higher, the AMSL level for the Thomson Line Concourse and Platform will be higher than that of the NSL. From the Thomson Line, 2 pairs of escalators on each ends of the platform will bring you down to the transfer level. (B2 to B4) From the North South Line, 2 new pairs of escalators at Doors 3 and 10 of the southbound platform will be constructed to bring you to to the transfer level (B3 to B4). For barrier free linkage, the existing NSL concourse-platform lift will be extended one level down to the transfer level (B2 to B4). A pair of travellators will be installed across the span of the transfer.

The NSL station will undergo intensive A&A works and underpinning, which will prove to be challenging without disrupting the operational status of the existing busy station.

Future subway and paid link to go beneath the existing Orchard Boulevard

Bored Tunnelling
A launch shaft will be built north of the station (near the Paterson junction) for the drive of an EPB TBM to Orchard Boulevard. The existing POB along Orchard Boulevard near Wheelock will be demolished so as to extract the piles in the way of the tunnelling route. A new POB will be constructed to replace the existing bridge. There will be 1 cross passage between ORC-OBV.

C&C Tunnels and TSA
A cripple siding will extend the cut and cover portion of the site south of the station all the way to Grange Road. This will be an extensive site being one of the temporary staging areas (TSA) for trackwork. The overall site will also be shared with various system wide contractors (SWCs).