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SIGNALLING & TELECOMS
An International Metro Review
CLIVE KESSELL
T
he latest Aspect conference of the Institution of Railway Signal Engineers (IRSE) was held in Singapore, and a report appeared in last month’s Rail Engineer. However, due to its location, the first time that Aspect has been held outside the UK, it was inevitable that much of the proceedings would be taken up with Metro technology and operations. Today, most large cities have a metro system, but the types and variety of systems in terms of sophistication, capacity, safety provision and engineering are almost bewildering. Few, if any, are identical, standardisation being virtually non-existent. Proprietary systems from many different suppliers dominate the market but, in order to keep abreast of the latest technology, these same systems are updated on a regular basis such that lines equipped with one technology may be different to another technology inside the same metro network. This has both advantages and drawbacks. It is good that the latest technology is deployed, so as to maximise operational requirements, but the interworking of rolling stock between lines, spares holdings and staff familiarity can be a real problem. Many systems exist under the CBTC (Communications Based Train Control) banner but, even here, the means of achieving the vital transmission link can vary: coded track circuits, track loops and radio. Several of the papers presented at the conference explored the different metro engineering practices and operation. Whilst this gave an opportunity to ‘showcase’ the systems in particular cities or countries, it did highlight the variety of systems deployed and the challenge when planning new investment.
Singapore SMRT. Rail Engineer | Issue 161 | March 2018
Singapore itself has a superb metro system, so commented Chua Chong Kheng, the deputy chief executive of the LTA (Land Transport Authority). The first line opened in 2003 with many more since and a further four extensions being built. The lines have a mixture of different proprietary CBTC systems, with much of the equipment being duplicated. Single points of failures do, however, occur. The ongoing objective is to have everything duplicated, including point machines. Track circuits provide secondary train detection should the radiobased primary systems fail. Problem areas are radio spectrum availability and the lack of interoperability and interchangeability between the different systems. These issues were to be a common theme at Aspect.
Metro trends and challenges Whilst metro technology has advanced massively in the last two decades, the decision-making process for new or upgraded provision has become ever more complex, with an increasing number of factors needing to be considered, according to Andrew Love from SNC-Lavelin. Many are obvious: