Sunday, September 21, 2014

Mount Pleasant Earthworks

At Mount Pleasant, KTC has been subcontracted to facilitate the demolishment of the old police academy blocks. Works started since our previous update in June and the site had just recently been fully cleared. Earthworks are now underway to flatten the land before works on the retaining wall fully begin. 2 piling rigs and silos have been set up west of the site.

Overview of Mount Pleasant

The station would mainly serve CJC and the neighbouring residents within Chancery Hill, across the PIE

Friday, September 19, 2014

Caldecott Piles

Piling works continue at the Caldecott site. The station's ERSS will be constructed using secant bored piles. Multiple cases are currently being driven into the boundaries of the station box and cripple siding tunnel. Toa Payoh Rise has completed its temporary road diversion, for the construction of the two entrances on both sides of the road. The diversion will remain till Q3 2018. Vibration meters have also been installed within the Circle Line station by Ryobi, the monitoring contractor for T212 & T213.

Prior to the commencement of tunnelling from ULS, Samsung would temporary handover site possession (where the original road aligned) to Sato Kogyo to facilitate ground improvement works for TBM docking. This is expected to take place around the middle of 2015 and last a couple of months.

Toa Payoh Rise coming down from Lorong 1
Diverted Toa Payoh Rise
Aerial view of Caldecott
North face

Wednesday, September 17, 2014

Bright Hill - Once Stacked

Bright Hill station, more commonly known as Sin Ming or 'T7' station during the planning stage of the line, was originally designed to be a stacked interchange with the future Cross Island Line. Along the tunnel alignment to Upper Thomson, 2 escape shafts had been planned to be constructed within Flame Tree Park and Windsor Park due to the semi-stacked configuration of the tunnels.

The original plans were scrapped at the last minute, and the architect rushed out a new set of drawings in May 2013. The twin bored tunnels are now level with each other, omitting the need for the 2 escape shafts as the cross passages can be conventionally constructed by mining. The new design incorporates two provisioned box tunnels at the roof of Bright Hill station for the future Cross Island Line (CRL). The box tunnels are orientated parallel with Sin Ming Walk/Avenue, giving a strong indication that the CRL will head straight into the Central Catchment towards Eng Neo. There will also be a stub tunnel abutting from the Woodlands bound tunnel, believed to be for the sharing of locomotives between the 2 lines.

Progress Update
Under T211, a replacement sports facility is being built for Bishan Park Secondary School as the existing one would be demolished for the station construction. The facility will be ready by November this year. Preparation works are underway for a road diversion too.

T211 Site Office overlooking the Bishan-AMK Park
New sports facility U/C. A temporary bus stop can be seen being delivered on a trailer within the site as well.

Monday, September 15, 2014

Upper Thomson Diverts

After 3 months of preparation works, Sato Kogyo has successfully implemented their first traffic diversion along Upper Thomson Road at Lakeview, where the future launch shaft (ULS) sits. The old pedestrian overhead bridge (POB) will be demolished at once, and piling works will begin for the launch shaft by year end once the site is cleared.

Upper Thomson Launch Shaft (ULS)
ULS will launch out 3 Slurry TBMs - 1 which will do a double drive to Upper Thomson, and another 2 towards Caldecott station. A Slurry Treatment Plant (STP) and Gantry Crane will be constructed along the former road. The team hopes to launch the first TBM by the end of 2015. Excavation of the tunnels will take some 18-24 months, and might possibly drag on into early 2018. Once the tunnels have its first stage concrete (FSC) completed, the cross passage within the shaft will been built. The shaft will be backfilled and reinstatement on the surface will only take place then.

T212 Tunnel Chart
Upper Thomson Station (UTS)
Canal diversion work is still on going at the station side. For the ERSS, Upper Thomson would be implementing the diaphragm wall construction. Trenching works should begin by year end.

ULS pre-diversion (September 12)
Upper Thomson Road on Sunday morning
Station side

Saturday, September 13, 2014

Ang Mo Kio Avenue 4 Diverts

The groundbreaking ceremony for Mayflower station was commemorated along with Lentor last Saturday. At the Mayflower site, Avenue 4 has just been diverted last week to facilitate the construction of the bored piles for the retaining wall. The diversion will remain till end 2015, when the SBP construction is completed.

The ERSS of a station can be constructed using diaphragm walls as seen at Springleaf and Lentor. Another method of constructing the underground structures would be the use of secant bored piles (SBP). Over at Mayflower station, this method will be adopted.

Secant Bored Pile Construction
The pile's casing is first drilled into the ground, leaving 1-2m of the casing head exposed to the surface. The exposed cylinder guides the excavation of the bored pile, which is carried out next using a rotary drilling rig. The soil surrounding the borehole is supported by the casing. If the casing is not long enough to reach the required depth in the ground, bentonite slurry is used to support the soil below the casing. After excavation is complete, the reinforced steel cage is inserted into the casing, and concrete is poured. The casing is then removed and the retaining wall or ERSS is completed.

Mayflower Station
Diverted AMK Ave 4 at the junction with St 13
Groundbreaking Ceremony on September 6
Commencement of drilling for the secant bored pile

Thursday, September 11, 2014

Lentor Drive Diverts

Much changes have taken place at the Lentor site throughout the 3rd quarter. The junction between Yio Chu Kang and Ang Mo Kio Avenue 4 has been diverted to accommodate the road diversion at Lentor Drive, which has been re-routed to skit around the proposed station box. 3 crawler cranes and a hydraulic grab machine is currently on the site.

Mentioned in the Springleaf update, a hydromill trench cutter is one way of excavating the trench for the d-walls. An alternative method would be the use of a hydraulic grab, which physically excavates the earth via clamshells. This machine is feasible for excavating panels of shallow depths in soft ground conditions. Lentor station will be constructed top-down.

At the groundbreaking ceremony, it was revealed that CR5 will be procuring their 2 TBMs from China Railway Engineering Equipment Group for the drives from Lentor to Mayflower station via 5XO. This is the first time CREG's TBMs are being used in Singapore soil.

Preparations are underway for the initial road diversion at the crossover site. The road will be diverted east of the original alignment. 5XO will be structurally completed and backfilled by 2017. The road will be realigned then.

Lentor Drive has diverted
Groundbreaking Ceremony on 6 September
Prime Minister Lee viewing the exhibit of the T209 TBMs which will be manufactured by China Railway Engineering Equipment Group

Tuesday, September 9, 2014

Springleaf & Tagore

As of today, 6 crawler cranes and 1 piling rig lies at the Springleaf site. A hydromill trench cutter has been attached to one of the cranes, marking the start of excavation for the diaphragm walls.

Trench excavation process
2 cutting drums are attached to the base of the trench cutter, operating in reverse circulation as it excavates the earth. As it excavates, soil is loosened, broken down and mixed with a support fluid which is then pumped to the desanding plant at the surface via mud pumps. The slurry is then cleaned and subsequently recirculated into the trench.

Springleaf Station
Tagore station

Sunday, September 7, 2014

Contract T206 & T207

Contract T206
The inaugural tunnel launch for the Thomson Line is expected to be held under this contract at Launch Shaft 2 (LS2), for the launch of 2 TBMs to Woodlands station. Excavation for LS2 is scheduled to begin by the end of the year, and the project team hopes to have the shaft ready to launch the machines in 8-9 months. Shortly after, another 2 TBMs will launch out of SBAB towards Woodlands South station. All 4 TBMs are scheduled to dock by the end of 2015.

T206 Tunnel Chart (Reception tunnels in red)
STEC has recently taken possession of the SBAB site. A crawler crane and 2 piling rigs has been brought in. West of SBAB, the escape shaft at Avenue 12 has also been hoarded up.

Contract T207
At the RTS facility site, a crawler crane has arrived onto the site and piling has begun. Tunnelling will begin slightly later under this contract as both launch shafts is being constructed by the neighbouring contractors requiring a handover process. Site possession under Shimizu is scheduled for end 2015 and early 2016 for the launch shaft at Springleaf and SBAB respectively.

T207 Tunnel Chart
RTS Facility Building site alongside the SLE
LS1 and LS2 amidst the diverted Woodlands St 17
Sembawang Airbase & Escape Shaft
Hoarding for Escape Shaft along Avenue 12

Friday, September 5, 2014

Woodlands Drive 16 Diverts

As the existing Woodlands Drive 16 cuts through the Woodlands South site, an interim road has been created to go around the site area. The road however has not yet been opened to public. Works are also underway for another road diversion along Avenue 1. The road will be shifted closer to Christ Church Secondary - this is to facilitate the construction of the station's earth retaining stabilizing structure (ERSS).

Northern end of station box where a road diversion for Avenue 1 is being prepared
The woodlands South site office is powered by solar panels. SBAB can be seen at the left background

Wednesday, September 3, 2014

Piling at Woodlands

Following the groundbreaking, South Woodlands Drive has seen a road diversion. To date, a total of 7 crawler cranes and 6 piling rigs flood the site. Works are currently being focused on the crossover tunnel which will sit below the existing road junction of Avenue 2/5, hence the need for a future road diversion which can be expected soon after sewer diversions are completed by T2119A.

Under the neighbouring tunnel contract T206, 2 TBMs boring the mainline tunnels from LS2 are planned to dock at this crossover tunnel by the end of next year.

South end of Woodlands Station