Downtown Line 3 May/Jun 2016 Update: Part 2

As promised, here is part 2 of the DTL3 construction update featuring DT28 to DT35. Stay tuned for our next update!

DT28 - Kaki Bukit
Kaki Bukit Ave 1 was reinstated on 24th Apr 2016. Surface structures are at the final stage of completion.

Downtown Line 3 May/Jun 2016 Update: Part 1

Following the completion of DTL2 and the commencement of above ground works on the DTL3, we bring you a special update before DTL3 fully completes by 2017. Here is part 1 featuring DT20 to DT27, we will bring you DT28 to DT35 within the coming week.

DT20 - Fort Canning
Entrance and surface structures are almost completed, pending cladding and architectural finishes work. It looks like the ITS Centre entrance has been structurally designed to allow future developments above.

Tunnelling Completes for Downtown Line

The final Tunnel Boring Machine under C926 docked into Tampines West station from the Prison Shaft yesterday, completing the 42km long Bukit Panjang bound tunnel for the Downtown Line.

Completion of all bored tunnels under DTL3 on June 8, 2015

Expo Bound Tunnel Completes

The last frontier of the 42km long Expo Bound tunnel for the entire Downtown Line have just been successfully broken through at Tampines West station. The TBM went through an arduous journey during its first drive towards Bedok Reservoir. 3 months of reassembly works were done at the Prison Shaft prior to the commencement of the second drive towards Tampines West. The breakthrough marks the retirement of the machine on the MRT project, as well as a complete linkage to the network of underground tunnels within the Downtown Line.

Tunnel Chart for DTL3, Apr 2015

Final TBM Launch

The last Tunnel Boring Machine (TBM) for the 42km Downtown Line has launched from the Prison Shaft today. The ∅6670mm STEC EPBM will spend the next 2.5 months boring the 350m Bukit Panjang bound tunnel towards Tampines West Station, with the final breakthrough scheduled in June.

It's sister Expo bound machine is currently about 75% through the tunnel excavation and should arrive at Tampines West in 2 weeks time.

2 Tunnels To Go

The Expo Bound TBM has completed mining from the Stadium shaft and docked into the tail wall of Tampines Central station last night, concluding tunnelling works within the Stadium Shaft. The final BP and Expo bound tunnel remains uncompleted between the Prison Shaft and Tampines West Station. Site pictures of the Stadium Shaft were taken by Mith252 earlier this month.

February 1 - Remaining few precast ring segments on the shaft surface prior to the breakthrough 10 days later

TBM Tunnel Chart for DTL3, February 2015

Prison Shaft

3 tunnels remain under C926, which ought to had completed prior to the end of 2014. There have been several complications within the project, with poor project management as one of the contributing factors to the lagging progress. We have a final look at the Prison Shaft where the shield segments of the Bukit Panjang bound TBM has yet to be lowered down. This very machine will be at the face of the breakthrough ceremony at Tampines West to mark the completion of tunnelling works for the Downtown Line in about 4 to 5 months time. 

As of now, only its sister Expo machine has been lowered and in the process of assembling, with the main drive commencing next month. The BP machine should follow suit in March.

Close look of the shield of the BP TBM sitting beneath the gantry crane

Route of the 4 tunnel drives from the Prison Shaft. The highlighted section leftwards to Bedok Reservoir represents the completed bored tunnels, which ends abruptly in the middle after the team stopped updating sometime back in October

3 Tunnels To Go

The 4th final TBM for the Downtown Line broke through the walls of the Tampines Central Station this afternoon. The completed Bukit Panjang Bound tunnel was among two drives executed by GS under C925, which faced numerous setbacks during the early phase of the tunnelling works along the Expo Bound tunnel due to the discrepancy between the excavation progress of the launch shaft and adjacent cut and cover tunnels which were meant to house the backup gantries. Due to the lack of space during the circumstance back then, a muck pump system was proposed by GS with an aim to reduce time loss to the project, however at the expense of a slight increment in cost - which was ultimately approved by the LTA.

The technology brought about great success for GS nonetheless, and today's significant breakthrough marks the end of excavation works for the 10 tunnels they've bored along the Downtown Line projects. 3 tunnels remain within C926 along the Tampines West sector.

DTL3 January Tunnel Chart

Breakthrough of BP bound tunnel at Tampines Central 

Geylang Bahru Cast

Phase 3 of the Downtown Line is beginning to surface upwards with casting works on the substructure the main scope of works at present. We should see the first few superstructures rising by the end of the year. DTL3 is about a year's progress behind stage 2 for a rough comparison. The completed concourse and platform slab at Geylang Bahru is viewed in this update.

Photos courtesy of Hor Kin

Retrieval of S693

Following its breakthrough 2 weeks ago, the cutterhead of the final Herrenknecht TBM was lifted out of the retrieval shaft at Tai Seng Facility Building (junction of Airport Road & Bartley Road East) a day before New Year's Eve. This is the last TBM for the Downtown Line to be retrieved, with the shields of the remaining 4 machines to be abandoned in-situ upon docking.

Cutterhead being lifted up - viewed from the Bartley Viaduct

December Tunnel Progress

Nov 29

S761 has just completed excavation of the Expo Bound tunnel between UPC and XPO, marking the end of its second and final drive.

Dec 5
After a long and arduous drive, the BP bound machine from the prison shaft has docked at Bedok Reservoir at last. The machine will begin to dismantle while the cutterhead and essential electrical components within the backup gantry be brought back to the surface to be reused for the second drive to Tampines West. It will join its sister machine to be the final TBM launch of the entire Downtown Line, estimated in February 2015. 6 tunnels remaining.

We thank Karthik & Sankar from KTC & Tritech for the consistent updates.

DTL3 Tunnel Progress as of 13 December. 4 tunnels remaining.

Dec 12
The final Herrenknecht TBM along the entire Downtown Line has just docked at the completed Tai Seng Facility Building this morning. S693 (TBM2) completed a 1445-ring drive (2.0km) from the Ubi launch shaft to TSFB for the Reception Track 6, tunnelling one of the longest drives along the DTL. This is Nishimatsu's final breakthrough within C929A as the tunnel contract wraps up.

This is also the DTL's final breakthrough for a single-driven TBM, with the remaining 5 TBMs along DTL3 executing or preparing their second drive.

With great thanks to the tunnelling team from Nishimatsu for the frequent progress updates.

Dec 13
The Expo Bound TBM from the Stadium Shaft has docked into Tampines Central Station. 4 tunnels to go.

Herrenknecht, Nishimatsu and LTA C929A team gracing the breakthrough of S693 at Tai Seng Facility Building

November Tunnel Progress

November 13

TBM2 docked into the Upper Cross Street retrieval shaft earlier today. The completion of this Expo bound tunnel structurally links the network of DTL tunnels from Gali Batu to Bedok Reservoir on both bounds.

November 23

The BP Bound TBM has just launched at the Stadium Shaft towards Tampines Central. This is also the final TBM launch out of the Stadium Shaft. Breakthrough is estimated around Chinese New Year 2015.

For the month of December, we can look forward to the
- Breakthrough of Expo Bound TBM between Stadium Shaft and TPC (926)
- Breakthrough of BP Bound TBM between Prison Shaft and BDR (926)
- Breakthrough of Expo Bound TBM between UPC and XPO (923)

DTL3 tunnel progress as of Nov 23

C929A UBI Launch Shaft

Nov 13 - Breakthrough of C937 TBM2 at Upper Cross Street

C929A Bracing for CP Excavation

CD Drill - Tampines East

A safety drill organized by the Civil Defence and GS E&C was held at the Tampines East site today.

October Tunnel Progress

Tunnelling milestones achieved towards the end of October:

- Launch of S761 from UPC to XPO EP bound

- Breakthrough of Expo bound TBM from Prison Shaft to BDR

October Tunnel Progress

FSC completed in BP bound tunnel between JLB and BCL this month

Geylang Bahru progress

Over at Geylang Bahru station, progress has been quick with the station reaching the mezzanine level. Following the casting of this level, the station roof slab will be cast. Like Expo and Tampines East stations, concrete pumping was on going during the Deepavali public holiday.

September 2014 - Casting of the mezzanine slab.
Photo credit - Wong Hor Kin.

September 2014 - Casting of the mezzanine slab.
Photo credit - Wong Hor Kin.

Tampines West progress

Tampines West station has only begun excavation work recently, unlike its counterpart and twin station Tampines East, which has already begun casting the station structure. The ground on which the station is sited is made of sand though, which can explain the slower progress to ensure minimal movement of the neighbouring HDB block. However, the saving grace is that sand is easier to excavate than harder granite so excavation can be done pretty quickly. Like its sister station, Tampines West was also planned with 4 exits although only 2 have been approved for construction.

Ground level plan of Tampines West station.

Concourse level plan of Tampines West station showing all 4 exit connections.

Upper Changi & Tampines East progress

Following the line down from Expo station, we passed by Upper Changi station. As there aren't many viewing points for this station, not much is known about the progress.

Having passed through Upper Changi, the line cuts through Tampines East. From the nearby HDB blocks, one can look deep into the excavation trench. Part of the tunnel walls are up at the cripple siding cut-and-cover section just to the west of the station. Concrete pumping was still going on despite the fact that it was a public holiday. Additionally, work for entrances C and D have commenced with the clearing of land. These additional entrances were designed as part of the station though they were only approved for construction at a later stage after the main station had commenced construction. As such, these entrances will open later than the station itself, some time in 2018.

Tampines East station seen from Avenue 7. The area in front of the HDB block is being cleared for Exit C.

Expo's roof slab

On Deepavali 2014, the team was busy running around gathering some updates and information to bring to you. We start at the eastern end with Expo station where works, as rightfully should be, were fully underway. The Samsung team here has made decent progress and the roof slab for some parts of the station is being done. It seems that original plans for the station have been modified and it would now include a paid linkway to the Changi Airport Line station. Most part of this station is built via the top-down method which means that casting of the station structure starts at the bottom. To have the structure near the top being built, it means that the basic structure is at a fairly advanced stage of construction.

Expo station site looking towards the over run tunnel and Expo facility building.

C935 and C936

Recently, the LTA released a set of photos on Facebook showing the under-construction Bencoolen station. You can view the post here.

TBM cutterhead with cutter discs being removed. The TBM shield skin will be abandoned here and tunnel ring cast within.
This is what the TBM looked like before.

C910A by CTCI

As mentioned in the previous post on Bedok North, CTCI is the trackworks contractor for stage 3 of the Downtown Line. Works have already begun on site for the laying of tracks along stage 3, beginning with the immediate vicinity of Bedok North. This will be a hub from which all tracks along stage 3 are laid. The other Temporary Staging Area (TSA) will be located at Bendemeer station where the former tunnel works staging area has been cleared (more later on).