As a long time advocate of public transport in Auckland I feel a certain sort of glee at the huge groundswell of support for a CBD rail tunnel in Auckland. With the likes of our new mayor Len Brown pushing hard it seems we will soon have unstoppable political momentum for the project. After a hundred years or so of waiting it seems Auckland will kick start the 21st century with a city rail tunnel.
The benefits of this project are many: new underground stations within walking distance of anywhere in the CBD, a faster route for the western line, improved interchange opportunities and of course relief of the capacity constraints at the current Britomart terminus of the rail system. Another oft-overlooked benefit is one of ‘prestige building’, a process that has already started with Britomart. Once we have new shiny new trains zipping through flash new underground stations at speeds of over 100km/h, the old perception that public transport is for ‘losers, cripples and dole bludgers’ will be left behind faster than a driver sitting in gridlock on the motorway.
Taken together these all mean much faster door to door trips, far better service frequencies and greatly improved reliability across the network, which all leads to massively improved desirability. With a CBD tunnel the rail system won’t merely offer peak hour travel times that are competitive with the car, it will blow them out of the water. In short, patronage on the rail system will skyrocket once the CBD tunnel is built.
This however leads us to one very important question: Will it be enough?
This question has been an ongoing debate on the CBT forums for years now. Will extending a two track CBD tunnel from Britomart to the Western Line provide enough capacity to meet the growth it is bound to cause? Should be we aiming to spend more and build it bigger to start with?
On one hand we have the ‘do it right the first time’ camp. These guys point to past planning failures like the four lane harbour bridge, and suggest that we should double or triple the budget for the city tunnel to ensure it has at least four tracks and decades of room for adding new lines and growing patronage. On the other hand we have a ‘step by step’ camp, who see the CBD tunnel as relatively affordable and realistic option that can be added to in the future to meet growth, perhaps with new links and additional tunnels.
Personally I lean towards the second camp. I certainly would love to see a four track mega tunnel under Auckland central but to be realistic we are lucky to see even the proposed two track one funded and built. The idea of doubling the budget to three or four billion is simply ludicrous given the political climate, plus there isn’t any need to build everything the city will ever need in the first instance. In fact to spend a lot of money to build infrastructure that isn’t actually going to be used for ten or twenty years is akin to setting money on fire. Ten years of compounded interest payments on a billion dollar loan for an empty pair of tracks is a disastrous waste of public funds.
However, the point about needing to meet the growth in patronage still stands, so the answer needs to be somewhere in between. To be realistic we just can’t afford anything more than a two track tunnel, so we need to maximise the benefits of those two tracks to the very last drop. I’ve previously posted a concept of having the new tunnel bypass Britomart rather than join to it, and extend all the way to Quay Park junction. This way the entire capacity of the new tunnel would be in addition to the existing capacity of Britomart, and rather than mixing all trains in Britomart we get to keep a terminal station separate to the new metro style one.
I still think this would give a very good outcome for a relatively small extension to the project, but at the end of the day it would still require several hundred million dollars more funding. In the current climate this option seems pretty unrealistic. So with this in mind I have gone back to the drawing board to see what could be done very cheaply to maximise the capacity of the proposed CBD tunnel once Britomart is one of its stations. Based on the idea that we will only get a two track city tunnel, here are a few ideas that might make the tunnel as lean and mean as it can be:
1) Maximise frequencies of trains through the CBD tunnel
Designing the tunnel for very fast headways is a great way to maximise the capacity of the system without the need to build extra tracks or lines at great expense.
Right now the best a rail line can achieve in Auckland is about twenty trains an hour each way and at this level the CBD tunnel could support forty trains an hour in total. That’s not bad compared to the current capacity, but this tunnel is going to be the backbone of the public transport network for many decades to come so the more train capacity the better. Luckily the recent CBD tunnel report suggests that with the right signalling system the same tunnel could support thirty trains an hour each way, or one every two minutes. Basically this means a 50% increase in the capacity of the entire system from a small additional expenditure on superior signalling. Even if they install regular signals to begin with a little attention to the design of the tunnel would allow these to be retrofitted once they are needed.
2) Grade separate Quay Park junction
Sixty trains an hour through the tunnel would be fantastic, but this wouldn’t be much use as long as the flat junction at the start of the tunnel can only handle half that.
Right now Quay Park junction is a bit like a crossroads with traffic lights. If traffic coming down from Newmarket has the green light then traffic coming from Orakei had to sit stopped at a red light. Likewise once Orakei traffic gets the green, the trains from Newmarket have to stop and wait until the track is clear for their turn.This is actually the weakest point on the network and we will never get much more than 20 trains an hour each way with a flat junction.
The answer is to grade separate, which is the rail equivalent of turning a traffic light intersection into a motorway interchange. As Quay Park is like merge between two motorways heading the same way, this is actually pretty simple: it would only need one track elevated over two other to remove all conflicting connections. A simple viaduct could carry one track heading out of the Britomart throat tunnel, up over the Eastern Line tracks and then curve around to join the line heading to Newmarket again. This would be essential once the CBD tunnel is built, but it would also help get a couple of extra trains an hour into Britomart in the mean time. They should really look into doing this cheap viaduct now.
3) Level boarding on CBD tunnel stations
Having the platforms of the CBD tunnel stations at the same level as the train floor would be a very simple way to boost efficiency. Level boarding makes it a lot faster for people to board en masse as there are no steps to negotiate or trip over, and no unwieldy gap to leap. Furthermore it would allow people with bikes, prams or luggage, or those using wheelchairs or mobility scooters to board themselves rapidly with a minimum of fuss. They current wheelchair system where the train driver has to park the train, hop out of the cab and muck around with a folding ramp simply will not cut it in the city tunnel with super frequent trains.
From what I understand perfectly level boarding is not possible on some suburban platforms due to issues with freight train clearance, as full height platforms would foul the wagons as they passed through the station. But in the tunnel there will be nothing but shiny new electric multiple units, so there no reason why the platform edge can’t line up with the floor of the carriage to the millimetre. This is one solution that will cost nothing to implement, it just means the new station platforms need to be designed accordingly.
4) Lighting and identification
A very simple trick to boost efficiency would be to have lighting in the tunnel on the approach to each station. If this is designed such that the light appears about ten seconds before the train makes it to the station, it would provide an effective cue for people to make their way to the doors to be ready to disembark quickly and easily.
A further application would be to have these lights on only one side of the tunnel when approaching underground stations, so it signals which side of the train the platform will be on. People getting ready to exit the train will instinctively turn toward the source of light. Guessing which side the platform is on can be confusing, and in the case of people with prams, bikes or luggage, getting it wrong can end up delaying the whole train. A little bit of attention to the lighting would cost basically nothing, but add to the efficiency.
Similarly, having a colour theme for each city station will help people navigate and work out where they are. For example Britomart might be lit in cool blue, midtown a warm yellow, Newton in Green and K Rd could be the, er, red light district. Little touches like this cost basically nothing, but could improve the ease and efficiency of the system to no end.
To be continued in part 2