In 2010 Len Brown campaigned on three major rail projects, the CRL, rail to the Airport and rail to the Shore. If there was one issue with them though, it is that to some they are too bold. Despite getting strong support among many members of the public, vocal opponents point to primarily to their price tags as a reason not to build them. However when it comes to the second and third of the projects I mentioned above, I also wonder how much of the opposition to them comes from the mental block of getting over or under the harbours. If we had a rail line to Mangere Bridge or to Akoranga, how different would the argument for extension of the network be?
History and common sense has shown us that when it comes to building expensive infrastructure, it is best to break it down into smaller more manageable projects. There are a couple of prime examples. Earlier attempts at building the CRL also included double tracking and electrification. They fell over in a large part due to the massive cost of doing it all at once. More successfully we have seen the tactic employed across the motorway network where the system has been expanded one project at a time. With the Western Ring Route for example, lots of smaller projects have been much more palatable to the general public yet by the time it is completed, the cost could reach $4 billion. Had the NZTA or its predecessor attempted to build the whole thing at once there would likely have been a lot more opposition.
I guess what I am getting at is that we need to find ways to break down projects and reduce costs wherever possible. In the case of the two rail projects mentioned at the start, getting rail across each of the harbours would likely change these projects from looking massive and expensive, to ones that we could break down over a period of time, extending the network one station at a time. At this stage the thinking about rail to the shore seems to be focused on integrated it into the same tunnels as a road crossing. For rail to the airport you may remember hearing that the recently completed duplicate Manukau Harbour crossing was future proofed for rail. But was it really?
Well it kind of was, but it turns out not in a way that seems to be that useful.
The story goes something like this. Transit, the predecessor to the NZTA, wanted to build the duplicated harbour crossing. They, acting with their motorway only blinkers on, came with with designs and proceeded to try and get consent for the project. It was then that the Campaign for Better Transport and others became aware of just how mono modal the project was and challenged Transit to include provision for rail the the airport, something that had been on high level plans for some time. It took the threat of legal action for the agency to concede and start investigating how they could be done.
I have now been provided with documents from the time (7MB) which discuss the level of future proofing that was included in the project. It started with a high level investigation into what the potential route options were. They consisted of two routes on a separate bridge to the east of the motorway, one through the middle of the bridge piers, sharing some of them, and one to the west of the motorways. That was then narrowed down to two routes, the route through the middle piers (B) and the route to the west (C) as shown below.
So far so good and option B is what has been promoted to the public. However in my opinion, here is where things start to go wrong. Engineers found that because the bridge hadn’t originally been designed with rail in mind, that for option B, there simply wasn’t enough space to include a double tracked line. By this time the bridge had now been consented and the construction contract awarded. Changing the design enough to allow for a double track line was considered too costly. However it wasn’t only financial costs, but the need to get consents changed and that it would have caused delays to the construction.
That means the only option available if we are to use the newly built bridge is a single track line as shown above. You may notice it is called option B3. The reason for that is based on the engineering standards, the original route option was not only a single track but due to the curves it and issues should a collision occur, it would have seen trains limited to 25kph. By strengthening some of the piers and a few other changes, engineers were able to improve the option enough to allow the design speed to be improved to 70kph.
As the line not only serves the Airport, but also the commercial areas surrounding it and the residential areas of Mangere and Mangere Bridge, I suspect that we will eventually need to be running frequencies of at least 6 trains per hour in each direction. I simply can’t see a single track section being sufficient to handle that kind of service level without causing potential delays. That means that despite all of the talk of the new bridge being future proofed for rail, the only realistic option appears to build a double track crossing on a brand new bridge. Unfortunately there doesn’t seem to be any estimates as to what the cost differences between the two options are but I would have to imagine that double track option would be much more expensive.
More than anything, I think what this case highlights is the result we get when we plan infrastructure in isolation. Transits role was to build roads, yet if they taken a little bit of time to think about what the city might need in the future, they could have made changes to the bridge design early on that could have avoided this problem. Instead, as a result it appears that to fulfil the vision of getting rail to the airport, we will have to stump up for another bridge across the harbour. It also means that we are going to have to be extra vigilant when agencies describe a project as future proofed. It appears that what the engineers and planners call future proofed, isn’t necessarily what us, the general public would expect.