CR117 - Bright Hill update Q1 & Q2 2024

 

20 June 2024 - A view eastwards of the site stretching up to Eunoia Junior College.

It's about the middle of 2024 already. With time ticking away, we'd thought we'd bring you up to speed on the Cross Island Line (CRL)'s Bright Hill station progress for the first half of the year, combining the updates for both Q1 and Q2 into a single post. Somehow looking at the pictures, we think that would give us some more things to talk about than if the quarterly updates were done individually.

Western end of site
At the western end of the site, works are concentrated on the mainline tunnels that will connect to phase 2 of the CRL. The tunnels here will also form a junction, connecting to the existing turnout stub on the Woodlands-bound Thomson-East Coast Line (TEL) tunnel to allow maintenance locomotives to shuttle between lines. Work has been going on over the first two quarters to construct the Earth Retaining & Stabilising System (ERSS) - in this case made up of bored piles. Bored piles may be used in place of diaphragm walls, another type of ERSS, where the soil is hard or rocky.

Auger machines are used to bore vertical tubes, through which rebar cages are lowered into before being cast with concrete. This method requires coordination as the piles will need to overlap each other to afford the correct retaining qualities required. Thus the order in which the piles are constructed becomes important.

Besides construction of the ERSS, a road diversion was carried out in Q1 along Sin Ming Walk to allow for the creation of a work site abutting The Gardens at Bishan condominium.

12 February 2024 - A view of the TEL station's exit 1. Construction of the mainline tunnels was
ongoing behind the exit. Works were underway to divert a portion of Sin Ming Walk.

21 March 2024 - Ongoing construction of the ERSS walls behind Bright Hill station's Exit 1.
Sin Ming Walk was subsequently diverted closer to the former Bishan Park Secondary School
buildings.

25 April 2024 - ERSS works in full swing at the site behind Exit 1 and along Sin Ming Walk.

30 May 2024 - Various auger machines and crawler cranes on site to facilitate ERSS construction.

20 June 2024 - ERSS works continue behind Exit 1 and along Sin Ming Walk.

Along Sin Ming Avenue
Part of the works along Sin Ming Avenue will see the construction of the paid transfer linkway that will connect the existing TEL station with the new CRL station. Similar to the mainline tunnels at the western end of the site, ERSS made up of bored piles will be used to support the excavation site. Work has progressed with the casting of the roof slab beginning at the end of Q2.

12 February 2024 - Bored piling taking place in the road median in mid-Q1.

21 March 2024 - Works in the median of Sin Ming Avenue continue in end-Q1.

25 April 2024 - Soil improvement works taking place in the median of Sin Ming Avenue in
early-Q2.

30 May 2024 - Excavation works beginning for the site in mid-Q2.

20 June 2024 - Rebar installation underway with part of the slab cast as of end-Q2.

Eastern end of site
This section of the site has been busy over the past two quarters, seeing the beginnings of the launch shaft for the eastbound tunnel and crossover box next to a portion of Sin Ming Avenue. The launch shaft for the westbound tunnel has yet to be constructed at this point. Works over the two quarters have involved bored piling, excavation, casting of the roof slabs and even backfilling of certain portions of the excavated areas.

12 February 2024 - A view eastwards of the eastern end of the site in mid-Q1.

12 February 2024 - A close up view of the launch shaft area and crossover box at the eastern end
in mid-Q1.

21 March 2024 - A view eastwards of the eastern end of the site in end-Q1.

21 March 2024 - A close up view of rebar installation for the first ring beam of the launch shaft
for the eastbound tunnel in end-Q1. The top rebar of the bored piles next to the shaft was also
exposed for capping beam construction.

25 April 2024  - A view eastwards of the eastern end of the site in early-Q2.

25 April 2024 - Casting completed for the eastbound tunnel launch shaft. Work on rebar installation
for the crossover box roof slab continued in early-Q2.

25 April 2024 - A view westwards of the eastern end of the work site in early-Q2.

25 April 2024 - A close up westward view of the work site.

30 May 2024  - A view eastwards of the eastern end of the site in mid-Q2.

30 May 2024 - Most of the area for the launch shaft and crossover box had been cast. Telescope
excavators can be seen at the launch shaft area excavating soil.

30 May 2024 - To the immediate east of the launch shaft, an area bounded by sheet piles was
being excavated in mid-Q2.

20 June 2024  - A view eastwards of the eastern end of the site in end-Q2.

20 June 2024 - A close up view of the work site area in end-Q2.

20 June 2024 - Part of the area within the sheet pile section immediately abutting the launch shaft
had been back-filled as of end-Q2. This may be a mucking area to facilitate tunneling works.

Work is progressing at the site, as evidenced by the completion of the casting of the launch shaft at street level. However, bored piling is a time consuming process as it covers less area with each pile as opposed to a diaphragm wall panel. Thus, there is not much apparent excavation action taking place yet. The benefit is that Bright Hill is a rather shallow station, so the contractor Penta Ocean does not need to dig as far down - the TEL station is deeper than the CRL and the CRL will actually cross above the TEL as it connects to phase 2 in future.

This post will also be available on Instagram & Facebook on 21 June 2024.