Stevens - Excavation Completes

Excavation works for the station box are largely completed down to the paid linkway level, with the dismantling of the temporary earth retaining structural system commencing concurrently. Architectural works for certain portions of the concourse level have started ahead of the overall station BSC due to the delay in the project timeline.

The opening of TEL3 is currently being dragged by the progress of the station, which at present estimate is likely to be delayed by up to 6 months.

TEL3 Tunnel Progress, March 2019. The final TBM 4 is projected to breakthrough at Napier by the middle of Q2.

Stevens Station

Stevens Excavation

Excavation works for the station have reached the mezzanine level and are proceeding down to the platform level. The concourse slab has been fully cast, with RC works taking place at the mezzanine slab and mezzanine service slab. Preliminary works have started for entrance E at the Downtown Line structure which will form the basement 1 link to the TEL concourse.

Stevens Station

Stevens Diverts (IV)

The final and semi-permanent traffic diversion stage 5 has been implemented, which sees the worksite for the basement excavation and casting works situated in the center of both carriageway following the completion of the entire station roof slab. This layout is rarely preferred as it severely limits the working space and site movement of the construction activities, however necessary as the most optimal solution so as to not disrupt access from the residential apartments and side roads along both sides of the road.

Excavation works at the station to the concourse slab is in progress with the first section of the concourse slab cast. D-walling works are in progress at entrance B. The RTBM drive is almost completed and will reach the escalator shaft wall within the next few days.

Stevens station with TD5 implemented

Stevens - RTBM Assembly

Assembly works are in progress for the second launch of the compressed-air Rectangular TBM along Whitley Road. The TBM has been reused following the successful completion of the subway structure at T221 Havelock last November. The 37-segment drive is scheduled to start next month and be completed by the end of the year, following which the TBM will be dismantled and proceed for a third run at the TELC6 T311 Bedok South project.

Diaphragm wall works for the station structure have finally completed and casting of the roof slab is ongoing along the final zone. Traffic Diversion 4 will be implemented at the station next month in preparation of the commencement of excavation works at the station.

Assembly of 65 tonne CRTG gantry crane for the RTBM works at SCGS

Stevens D-walls (VI)

Construction of the diaphragm wall continues with around 45 more panels to be constructed for the station and Entrance B. Stevens is the sole station along the Thomson stretch with its earth retaining structure incomplete, and works are targeted to complete by the 4th quarter.

Preparations of the launch shaft structure for the arrival and assembly of the RTBM in Q3

Stevens D-walls (V)

The second portion of the stage 3 traffic diversion works had been implemented along Stevens Road last week, allowing for the construction of the remaining half of the station's diaphragm wall. Excavation works have commenced at Entrance C&D. 

The project's first tunnel completion for the 300m southbound tunnel between Dalvey LS and the station is due next week (TBM 4). Lack of soil profile understanding beneath private properties and portions of unfavorable geological conditions are hindering the tunnel progress towards Napier, as well as between Mount Pleasant and Stevens station.

Commencement of excavation works at Entrance C&D & Rectangular TBM launch shaft

Stevens Diverts (III)

The next phase of traffic diversion at the station will be implemented along the southbound carriageway by the end of the month for the next phase of the diaphragm wall construction. The diaphragm wall works for entrance C/D and the escalator shaft have completed and started respectively.

Roof slab completed over the center zone for the upcoming Stage 3A traffic diversion

Stevens D-walls (IV)

D-walling works progresses at the Stevens station. TBM 1 and TBM 2 have completed initial drive works and are transitioning to the main drive, while TBM 3 has just started tunnel excavation works.

T216 Stevens Station site

Stevens Diverts (II)

The stage 2 traffic diversion was successfully implemented along Stevens road at the beginning of June. The diverted northbound carriageway goes over the complete diaphragm wall panels and roof slab on the west side of the station. More than a third of the 155 diaphragm wall panels for the station perimeter have completed, and works on the diaphragm wall and utility diversions are now being carried out beneath the road.

D-walling works on the south end of the station box following the implementation of the stage 2 traffic diversion

Stevens - TBM Launch

The final 4 NFM slurry TBMs have been lowered for the T216 project. TBM 1 will commence excavation on the Changi bound tunnel from Mount Pleasant to Stevens by the end of the month, while TBM 2 drive the Woodlands bound tunnel from the Dalvey shaft to Napier from next month. Sewer diversion and JGP works are concurrently taking place with the continuation of the diaphragm wall works at the Stevens station.

Assembly of TBM 1 and TBM 3 at LS10 (Mount Pleasant)

Stevens D-walls (III)

D-walling works continue at the Stevens station, with a partial realignment of the northbound carriageway in November for the construction of the diaphragm wall in the center of the road. Piling works continue for the pipe jacking machine launching shaft at SCGS.

Over at the Mount Pleasant launch shaft, the Changi-bound TBM has completed assembly within the shaft and is likely in the midst of finalizing the electrical components - resulting in a delay faced by its sister machines at T208. The Woodlands-bound TBM is in the process of assembly at the completed Dalvey launch shaft.

Lowering of the NFM slurry TBM at the Dalvey Launch Shaft - December 21

Stevens D-walls (II)

Excavation of the Dalvey launch shaft is now midway completed. The slurry treatment plant is in the midst of installation beside the shaft. D-walling and piling works continues at the Stevens station. Updates for the launch shaft at Mount Pleasant can be found here.

Excavation and grouting at the Dalvey launch shaft

Stevens D-walls

Piling has commenced at the SCGS site for the rectangular TBM launch shaft. Hoardings have gone up beneath both flyovers for ground improvement works and the construction of the escalator shaft. Back at the station site, D-walling works are on going. The diaphragm wall panels of the Dalvey Launch Shaft have been completed and excavation works had just commenced on the dual circular-cell shaft.

T216 Stevens

Stevens - Deep Cement Mixing

Ground improvement works are taking place around the Stevens Station for the past couple of weeks. Due to space constraints, only a single auger has been utilized in boring around the station box for the DCM works. Across the road, hoardings have just been erected along a boundary within the SCGS campus which has been designated and temporarily acquired as part of the construction of the new underpass and entrances. This site is expected to house the launch shaft for the CREG rectangular TBM which will bore the underpass beneath the canal, and dock at the escalator shaft.

The entrances and underpass have been promised to be completed 2 years ahead of the TEL station completion, in a bid to provide better connectivity between SCGS and the then-operational Downtown Line, in addition to an earlier reinstatement to the acquired SCGS site.

D-walling works continue at the Dalvey Launch Shaft.

Update Preview - Dalvey LS

T216 Stevens Station

Stevens Diverts

One of our biggest highlights of this quarter's updates lies at the T216 project. An initial diversion has been implemented along the arterial Stevens Road last month, realigning both carriageways to the east. Utility diversions seem to be underway along the west side beneath the former road. With the complete demolishment of 2 Robin Close, piling works have commenced at Entrance B. Acoustic barriers have also been erected around the site area and with the innovativeness from the Korean contractor, the barriers exhibits a unique design replicating flora that were felled to blend in with the surroundings.

Kori have been subcontracted for the supply, fabrication, installation and dismantling of strutting and decking works for this contract. In addition, NFM Technologies will manufacture the 4 slurry Tunnel Boring Machines (TBM) to be utilized in this contract. This would the first time NFM's machines are being used to bore Singapore's metro tunnels. D-walling works are also underway at the Dalvey Launch Shaft.

T216 Stevens Station

12m high acoustic barriers

D-walling works at the Dalvey LS. The double cell circular outline of the shaft's ERSS will be identical to T206's Launch Shaft 2

Stevens Clears

Contract T216 is for the construction of Stevens station and 3 sections of twin tunnels. There will be 4 new entrances. Entrances D and C will be located along Whitley Road/Dunearn Road. Entrances A and B will be on either sides of Stevens Road. There were indicative plans to construct a crossover tunnel beside Malcolm Park where the Package C boundaries start, however the A/E consultant did not found it feasible to go with.

Stevens Station. Felled tree stumps can be seen along the road median.

Station

The main site will be under Stevens Road where the station box is located. A second site will be located under the northbound Wayang Satu Flyover for the construction of an escalator shaft. A third site will be located along Dunearn Road, along the walls of the existing SCGS. The underpass beneath the canal linking SCGS to the escalator shaft will be constructed by mining. The station layout has been explained here.

The station will be constructed top-down. In an effort to maximize space. the contractor will immediately backfill and reinstate the road once the roof slab is completed.

Tunnelling

A total of 4 slurry TBMs will be procured under this contract. For the tunnels between Mount Pleasant and Stevens, Contract T215 will build a launch shaft south of their site before handing it over to T216. 2 TBMs will launch out of Mount Pleasant and dock at Stevens station.

4 cross passages will be constructed between these 2 stations.

T216 Tunnel Chart

For the tunnels between Stevens and Napier, an independent launch shaft will be build off Dalvey Road. Spectacular, the Dalvey launch shaft will be double cell circular, or better interpreted as a peanut shape - the first of such design ever built here. 2 TBMs will first drive towards Napier, before relaunching back at Dalvey for the second drive to Stevens station.

A cross passage will be integrated into the launch shaft before it is backfilled. The tunnels will go into a stacked configuration upon leaving the launch shaft towards Napier. There will be 1 escape shaft located at the junction of Fernhill Close and Nassim Road. To respect the privacy of residents in the neighbouring homes, we will not be doing updates here.

T216 Site Office located off White House Road. Earthworks for Dalvey Launch Shaft in the foreground.

Progress Update

The site office has been completed and is located along White House road, in front of the Dalvey launch shaft. The felling of several trees along Stevens Road had also recently be carried out. Earthworks are underway to flatten the site where the launch shaft is situated. SI works are being carried out at Entrance C. The SCGS wall has yet to be relocated. 2 houses will be acquired for the Stevens Road entrances. 2 Robin Close has been acquired and is currently in the process of being demolished. 133 Stevens Road has no signs of work.

Package C Renders

 A/E Consultancy services for package C of the Thomson Line were awarded to Aecom and SAA back in 2010. Effectively known as Civil Team 3 as construction works gear up, the design boundaries span from Whitley Road to Havelock. Stations included in this section are Stevens, Orchard Boulevard, Orchard, Great World and Havelock. Napier station is not included inside the design package as it is separately designed by the client.

Photos courtesy of SAA

Contract Awards - T215, T216 & T223

Contracts T215, T216 and T223 were awarded today. T215 is for the construction of Mount Pleasant station and associated tunnels. This contract has gone to RSEA - Eng Lee - Wai Fong Construction Joint Venture.

T216 will see the construction of Stevens interchange station and associated tunnels. This station will allow commuters to transfer between the Downtown Line and Thomson Line. This contract has been awarded to Daewoo Engineering.

T223 is for the construction of Maxwell station only. This stacked station will be built by home-grown company, Hock Lian Seng (HLS). Previously, HLS has completed the Marina Bay Circle Line station and are currently finishing the Downtown Line Gali Batu Depot.

Photo credits - LTA