Construction works has begun on six MRT stations under the second phase of the Cross Island Line (CRL), with completion targeted by 2032.

Six underground stations will be built over a distance of 15km, including two interchanges at the current King Albert Park and Clementi MRT stations which will connect commuters to the Downtown Line and East-West Line respectively.

The working names of the other four stations are Turf City, Maju, West Coast and Jurong Lake District. Works on the 15 stations under CRL phase 1 and the Punggol Extension are currently ongoing too.

At the CRL phase 2 ground-breaking ceremony on Monday (July 7), Acting Transport Minister Jeffrey Siow termed the line as an "outer ring" connecting to existing rail networks as well as the future Jurong Region Line.

With eight of the 21 announced stations on the CRL to be built as interchange stations, commuters will have more route options, which Siow said will help "better absorb the impact of service disruptions". 

He noted that this line will also open new windows for maintenance to be done, where such works may have to be scheduled during the day "at some point" in the future.

Siow added that the CRL will likely be the Republic's last east to west MRT line: "There is no space left for another line like this."

But he assured that authorities had planned ahead to meet future commuter demand — six-car trains will ply CRL when it begins operations, and it's designed to support longer eight-car trains if needed.

When Phase 1 and 2 begin operations, commuters can save up to 40 minutes when travelling from West Coast to Ang Mo Kio Industrial Park, for example.

Engineering studies for CRL phase three, at the Jurong Industrial Estate area, are currently ongoing, said the Land Transport Authority (LTA).

When fully completed, the CRL is expected to have a daily ridership of at least 600,000 in the initial years, and projected to grow to one million in the longer term.

Working with nature groups

Phase 2 of the CRL will pass through nature areas including the Central Catchment Nature Reserve (CCNR), Eng Neo Avenue Forest and Clementi Forest.

Studies were conducted before works started to assess any potential impacts on the environment, and an Environmental Monitoring and Management Plan has been implemented at the worksites.

The plan comprises several measures such as installing opaque screens and windows at the site offices to prevent bird collisions, creating fauna barriers and box culvert crossings to prevent traffic collisions with animals and wildlife-proofing food waste bins.

A new freshwater marsh has also been constructed at the CRL King Albert Park site to serve as a habitat for the fauna and flora from the existing marsh, said LTA.

Site workers will also undergo mandatory wildlife awareness training.

In his speech on Monday, Siow said he was the Director of Land Transport at the Ministry of Transport when the CRL was first announced in 2013. And there were public concerns about its planned route passing under the CCNR then.

LTA then engaged nature groups, and conducted environmental impact assessments with their consult. 

Authorities also engaged residents living near future CRL stations in the consultation process. 

"Shifting the alignment of the CRL for the planned route would add at least six minutes of additional travel time," said Siow.

"Six minutes may not sound like a lot, but it would change the route of too many commuters, and it would have made the ridership of the CRL unviable."

At last, it was decided that a 5km bored tunnel passing through the CCNR to connect the CRL Bright Hill and CR14 stations will be constructed using a large-diameter tunnel boring machine, said LTA in a media release on Monday.

With a diameter of 12.8 metres, the machine will bore through the ground only once. The tunnelling works towards the CCNR commenced in May this year, along with ongoing ground improvement works.

In his speech, Siow pointed to how LTA reduced the number of boreholes for soil investigation from 72 vertical boreholes to 16 to minimise disturbance to the CCNR.

"We took extra care when we drilled and we collected all the groundwater that was released so that it did not seep into the surrounding soil. We also installed cameras to observe the impact of wildlife," he elaborated.

Siow added: "It is not a coincidence that the colour chosen for the cross Island line on the train map will be green."

lim.kewei@asiaone.com