Fine-tuning the New Signalling System
Since we began regular system-level performance checks on the new signalling system for the North-South Line, we have received valuable feedback and suggestions from many individuals and organisations. I thought it would be useful to share with commuters the intricacies of implementing a new signalling system on an existing line.
Greenfield projects in railway engineering refer to those conducted on completely new lines, e.g. the Downtown Line, while brownfield projects are those executed on existing systems, e.g. the North-South and East-West Lines (NSEWL). New enhancements in a brownfield project would have to integrate seamlessly into a ‘live’ system.
A greenfield signalling project typically takes a few months of intensive daily testing involving thousands of hours. For a brownfield project, if we were to restrict the performance checks to only weekends, or engineering hours (i.e. 1.30AM – 4.30AM), it would take Singapore years to implement the new signalling system on the NSEWL. This is why we have no choice but to conduct checks throughout the day, including weekday peak hours, when trains are running at high frequencies with heavy commuter loads. In addition, we have about two million passenger trips on the NSEWL every day. It would not be prudent to shut down the lines for extended hours to conduct the performance checks.
My team is now ironing out teething issues with the new signalling system. Every time we encounter a problem, we systematically log and investigate the issue. We then work with the Land Transport Authority (LTA) and system supplier Thales to come up with hardware and software fixes to rectify the issues. When we began weekday checks, we encountered a number of software related issues that affected train services. After joint investigations with LTA and Thales, we managed to identify the root causes and developed operational workarounds while waiting for software fixes to be implemented by Thales.
Some – including my own friends – have asked why the re-signalling project takes so long. “Surely SMRT cannot be the first operator in the world to change signalling systems,” they exclaimed. A former classmate told me that one of her friends is now an engineering professor, and offered to have him advise us on this project. I had to clarify that this is unlike the Circle Line incident in 2016 when we dealt with unknown unknowns. We are adopting a planned, systematic approach to identify and rectify the issues in our signalling trials.
Each software update is thoroughly tested in the laboratory. It is also tested on the tracks during engineering hours, before being applied during passenger service hours. These fixes take weeks to be delivered. We are planning a software patch in the coming weeks. We hope for a smooth implementation.
The procedure is tedious, because no two railway systems are identical in the way they are designed and operated. The system hardware and software we have are customised for the unique local environment. While the system supplier had experience working with other operators in the world, they are unable to simply replicate the well-oiled systems of Taipei, Hong Kong and London, and import those here.
Safety is of paramount importance. The signalling system is like the brain that commands and controls trains on the network. We will fine-tune the signalling system and ensure that it can accurately track the exact position, speed and braking distance of all trains on the network. It will take us some time, but we are not taking any chances as far as safety is concerned.
My team and I have learned a lot from Singapore’s very first re-signalling project. We are keenly aware of commuter feedback and inconvenience due to the ongoing performance checks. I would like to assure commuters that we are working hard to get over with this phase of system renewal on the NSEWL. We remain committed to completing the performance checks as soon as we can, and to fulfil our promise of providing commuters with better journeys. Thank you for the patience and understanding.
Lee Ling Wee
Chief Executive Officer, SMRT Trains
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