The Cross Island Line Phase 2 (CRL2) project is an approximately 15-kilometre-long metro system in Singapore, consisting of six underground stations: Turf City, King Albert Park, Maju, Clementi, West Coast and Jurong Lake District. Two of the stations are interchange stations. King Albert Park station is the one that will connect to the Downtown Line and Clementi station will link the East West Line. Once completed and operational, the metro line will significantly reduce travel time for passengers in western Singapore, improve the connectivity between the east, west and northeast regions, and provide transport convenience to the existing West Coast and Jurong Lake regions as well as the emerging areas. Passenger service for CRL 2 is expected to commence in 2032.
Awarded by the Land Transport Authority to Obayashi Corporation and Shanghai Tunnel Engineering Co (Singapore) Pte Ltd Joint Venture, CRL2 contract CR202 involves the construction of a 5-kilometer tunnel between Fairways Drive and Sin Ming Walk. A 2-kilometre section of the tunnel will pass under the Central Catchment Nature Reserve at a depth of approximately 70 meters, compared to a depth of 20-30 meters for the remainder of the route. A Herrenknecht Mixshield with a diameter of 12.69 meters will be used to excavate the single bore tunnel, which will accommodate double track railways. To cope with the extreme geological conditions (fresh granite with a UCS of up to 290 MPa and extreme abrasiveness up to CAI value of 5.7), the mega-sized machine is especially equipped with a wear-resistant cutterhead with optimized disc cutters’ spacing for efficient rock cutting. Thereafter, a heavy duty roller crusher crushes the rocks smaller for a smoother slurry discharge. In addition, a special telescopic camera system in the excavation chamber allows to monitor the status of the cutting tools and the tunnel face without the need for hyperbaric intervention.
As this 5-kilometer tunnel will be the longest drive by a single TBM in Singapore, the TBM is also equipped with Semi Continuous Advance system to perform ring building and TBM advance concurrently, thereby increasing the tunnelling efficiency.
Factory acceptance of the Mixshield took place in August 2024.
