I read with interest the plans for the Cross Island Line (CRL) to traverse under the Central Catchment Nature Reserve (New rail tunnel can be done safely, say experts; and Robust measures to tackle any power issues in CRL, both Dec 6).
This tunnelling endeavour will be a first for Singapore, in terms of depth and complexity of the project. The procedures and practice implemented can provide valuable knowledge in deep construction, as the nation considers building downwards and using land sustainably and responsibly.
In addition to the expertise in planning and execution of the CRL tunnel work, the issues below should be considered:
•Use virtual reality computation techniques to conduct simulation studies of the experience of commuters travelling deeper into a tunnel, and find out the physiological effects for the commuter - such as air pressure, smells, temperature and sense of being in an enclosed space for a period of time.
•Plan and develop measures to prevent the occurrence of fire within the tunnels and to disperse smoke away from the tunnel.
•Review best practices from other countries on how people are evacuated in similar underground transport networks in case of emergencies. More studies need to be done for the proposed motorised trolleys or diesel-driven shunters mentioned by the Land Transport Authority.
•Monitor the effects on flora and fauna during the construction of the tunnel network. While below-ground boring and tunnelling equipment will be used for most of the affected nature reserve, some trees with deep roots may be affected. Drone-enabled X-ray mapping of tree roots and animal habitats should be done.
•Maintenance of the tunnels over time: After completion, engineers and consultants will need to be deployed regularly to check and maintain the various parts of the tunnel for issues such as water leaks, mould and cracks.
•Engage and inform the public of the progress of the CRL tunnel, in terms of safety features, facilities and funding.
As the nation embarks on this ambitious plan, it is good to harness its collective energies and ideas to develop an efficient and sustainable transportation network for all Singaporeans.
Tio Kheh Aun