When I discussed the main problems I had with Infrastructure NSW’s First Things First report, I mentioned that there were a few other issues I had with it which I had left out for the purposes of brevity. Those two were the potential for high density development along the Parramatta Road corridor and the problems caused by trying to retrofit the Harbour Crossing into a single deck metro system.
The cut and cover slot construction method proposed for the M4 East benefits from having much lower costs than a tunnel. The concept art for this shows an increase in housing density along a rejuvenated Parramatta Road (below). Suggestions for increasing housing density along Parramatta Road have been talked about for decades, and the corridor has been spoken of as being able to house some 100,000 residents. But high density needs good quality public transport to work (a motorway is not enough), just as good quality public transport needs high density to work. And what this proposal seems to be lacking is improved public transport, either Bus Rapid Transit or Light Rail, perhaps even an underground or aboveground metro, to carry large quantities of people along the corridor.
The Urban Taskforce is one group pushing for higher densities along Parramatta Road and its CEO, Chris Johnson, voiced his concerns for just this reason. This means one of two things: the opportunity for high density, walkable, sustainable housing will be squandered, or provision must be made for some kind of mass transit system to be built concurrently with the M4 East.
Infrastructure NSW’s insistence that a Second Harbour Crossing it too expensive and should be deferred until it is really needed also has its problems. One would be that the CBD rail lines could be shut down for months and access remain restricted for years as the existing Harbour Crossing is converted to single deck metro capability and then connected to lines that enter the CBD from the South. Such a conversion and link would also occur with a Second Harbour Crossing, but this would involve a new line built through the CBD which ensures that any lost capacity is made up by new capacity through this new line.
What the Infrastructure NSW report does not seem to appreciate is the complicated system of connections between different lines. Connecting trains on one line to another can often result in the use of flat junctions, which delay trains on other lines. Think of it like an intersection with traffic lights, if there is a green light for one road then there must be a red light for the other road. This is why there is a system of dives and flyovers on the rail lines between Redfern and Central, to allow trains to move from one line to another without disrupting trains on those other lines. But these connections are limited in what they can do, and to build in new ones to link up the lines the way Infrastructure NSW wants would result in the shut down mentioned earlier.
Taking the massive disruptions into account, along with the cost of retrofitting the existing crossing, and the lack of long term capacity improvements that it brings, you have to start to wonder if not building a Second Harbour Crossing really is as unaffordable as Infrastructure NSW makes it out to be.