Double-deck carriages were added to Sydney's rail network in the 1960s. Credit:Glenn Campbell When opened between 1926 and 1930, it was designed to serve 2.5 million people and now, 90 years on, we should not be surprised that the system is struggling to cope with a population of twice that size. It has of course been extended over the years to the eastern suburbs, South Coast, the Blue Mountains, Newcastle and to Sydney Airport. But this has not increased its capacity, rather only the size of its passenger workload. The last time capacity was added was in the1960s, when double-deck carriages were introduced. We have been told that the new Metro now being built between Rouse Hill and the city will make "all the difference", but this claim doesn't stand up to analysis. The only thing that is clear is that when opened in six years' time, the Metro will operate a shuttle service between Bankstown and Rouse Hill via the City and Chatswood.

Town Hall train station suffers from congestion at peak hour. Credit:Ryan Stuart The new technology will be fascinating, but it defies logic to suggest that somehow this will take pressure off the West, South or Illawarra Lines, to name a few. The only way to take pressure of the existing system is to build additional tracks on virtually all lines, because they are all operating at capacity in the peak hours. It may be that the NSW government has a vision of building an alternate metro-style network parallel to the existing double-deck system. Since no master plan has been announced this seems unlikely, but if this were the case, how long would it take to build? Can we wait that long? Can the double-decks carry the load till then? The most urgent need for additional track in the double-deck system is from the city to Parramatta via the Bays Precinct. The government has talked about this but has not yet made a commitment. Such work should be started now. Using tunnelling, it could be built quickly and would bring immediate relief. Just as urgent is the need to build a new underground railway station in the city on the double-deck network to take the load off Town Hall and Wynyard stations, where at times passenger congestion reaches dangerous levels. We have been told that the building of the Metro will include such a station but if the existing double-deck trains can't use it, how will it make any difference to today's levels of congestion?

It is the commuters using the double-deck system who are under pressure, not those expected to travel in from Rouse Hill. If it's true that land is now being acquired for this station, may we expect an early announcement of a start being made on its construction? There is yet one other option available to the government to increase the capacity of the existing network in the short term. Its signalling system is based on obsolete (1930s) technology and although apparently well maintained, it greatly limits the frequency of trains passing. Installing modern automatic train protection equipment would be a useful first step to equipping the entire network with an electronic train control system, or in-cab signalling. Loading Is it too much to ask the government to pause in its headlong rush to bring new railway technology to Sydney, and to spend some of its Metro millions on upgrading the existing rail system before it's too late?

John Brew is a former State Rail chief executive.