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 - TBM 2 Completes

Excavation works for the Woodlands bound tunnel from Mount Pleasant to Stevens completed today with the docking of TBM 2 outside the d-wall of the station. The NFM slurry machine was launched in September 2016, having spent the last 2 years completing the 1.44km tunnel drive. The final month of tunnelling works proceeded cautiously between the stacked DTL tunnels, as well as beneath the Wayang Satu Flyover and Bukit Timah Canal.

Its sister machine is approximately 100m behind and is similarly scheduled to dock at the station next month.

TEL3 Tunnel Chart - September 2018

Docking of TBM 2 (left) at the D-wall of Stevens Station (Photo: Oop Pocca)

Final TBM Assembly

Assembly works for the final TBM for the Thomson Line (C1-C4) are in progress at the Dalvey Launch Shaft for the 300m Woodlands bound tunnel towards Stevens Station. The said TBM is a refurbished STEC Earth Pressure Balance machine previously used on the line which had been additionally procured by the project team in an effort to achieve the crucial basic structural completion for TEL3 by the end of the year. The 5th machine supersedes the intended second drive of the NFM TBM 3, which is currently still excavating the Woodlands Bound tunnel towards Napier.

The choice of using an EPBM as opposed to the existing Slurry TBMs is likely due to the constraints for the Slurry Treatment Plant, which was designed to only accommodate concurrent tunnelling works for TBM 3 and 4. Favorable geological data obtained from the previous excavation of the parallel Changi bound tunnel likely bolstered the decision of using an EPB shield.

The TBM was lowered down in the second week of May and is scheduled to commence mining next month.

Internal assembly of TBM 5 being executed at Dalvey LS

TEL3 Tunnel Progress, June 2018

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

July Tunnel Progress

Tunnelling works are underway along all the projects along stages 1 and 2 of the line, with the first slurry TBM for the T211 project launched at Bright Hill this week. 5 bored tunnels have been completed by the first half of the year and a further 5-8 tunnels are envisaged to complete by year end.

TEL1/2 Tunnel Chart, July 2016

T206 - Launch preparations for the second drive of TBM 4 for reception tunnel 1 at Sembawang Airbase C&C (Photo credits: LTA)

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)

January Tunnel Progress

TEL1/2 Tunnel Chart, January 2016
(T206 - Reception tunnels emerge between the mainline tunnels in actuality, however shown otherwise on the chart for simple illustration)

Contract T202

Excavation of the Changi-bound tunnel is advancing at a slow pace and 2 cutterhead interventions have been performed since the launch of the TBM back in December. It's sister TBM is slated to commence mining on the Woodlands-bound tunnel by the end of this month.

Changi Bound Tunnel, T202 WDN-WDL (Dec 28)

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

October Tunnel Progress

TEL1/2 Tunnel Chart, October 2015

Contract T206

Excavation of the Changi Bound tunnel by S-893 commenced at the LS2 last month. 15 rings have been erected as of October 12, and 54 rings built as of October 25 (9% completed, ~ 3 rings/day). At the present advance rate, the estimated breakthrough for S-893 is slated around June 2016.

S-894 will commence excavation on the Woodlands Bound tunnel soon.

The T206 project utilizes the steel fibre reinforced concrete (SFRC) segments, a special type of tunnel lining which uses less steel, however is more durable and crack resistant. The segments were previously trialed on the C933 Downtown Line project and the LTA has extended the use of these segments along a 10km stretch of tunnels under the T206 & T207 projects of the Thomson-East Coast Line. The SFRC lining consists of 7+1 segments instead of the usual 5+1. The tunnel lining segments for T206 are currently being supplied by Kimlun in Malaysia.

Progress of S-893 on the Changi Bound tunnel between LS2 to Woodlands (October 24)

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

NFM TBM - Factory Acceptance (III)

Another slurry machine has been completed at NFM's Shenyang factory for Daewoo's T216 project.

NFM Slurry TBM for T216

NFM TBM - Factory Acceptance (II)

The first slurry TBM for T216, and the fourth overall produced by NFM for the Thomson Line project has passed its factory acceptance test last week. The machine should be delivered to the site by the Q4 of this year. Tunnelling works for the project should commence around the first or second quarter following the assembly of the STP and ancillary equipments.

FAT signed by representatives from NFM, NHI, LTA and Daewoo

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