Readers of my recent post may recall that I’m no fan of the proposed second harbour crossing. That has a lot to do with the fact it would actually be our third harbour crossing, and our third motorway crossing at that. With traffic levels static on the Upper Harbour Bridge and actually declining on the Auckland Harbour Bridge it seems a little silly to be planning yet another motorway across the harbour, especially once we consider how effective the busway has been.
It’s not actually a case of fewer people crossing the harbour each day, that figure keeps climbing, it’s just that all the growth has occurred on public transport. More and more people cross the harbour each day… on a bus. This begs the question, why aren’t we planning a public transport crossing? A projected cost of more than five billion dollars for a harbour tunnel and it’s all just for cars and trucks. Something needs a rethink methinks.
The real problem with proposals like this is that they just won’t go away. No matter how poor the business case, how low the BCR (around 0.2 to 0.4 if you’re asking), no matter how damned expensive… I just can’t shake the resignation that sooner or later this motorway tunnel is going to get built anyway. All it takes is one minister to start using words like ‘policy alignment’ and ‘strategic fit’, and all the extensively researched economic evaluations aren’t worth toilet paper.
With that though in mind I went back to the drawing board and started to think about how we could really make a harbour tunnel work. If it abso-friggin-lutely has to be built come hell or high water, what can we do to make it a real bonus for Auckland? How can it also improve public transport, walking, cycling and urban design?
After all, it’s not like this megaproject couldn’t have some additional benefits. For a start the plan is for the tunnel to carry State Highway 1 though to Spaghetti Junction and leave just citybound traffic on the existing bridge. If they do this right the new tunnel would function as a bypass of the CBD, by taking all that heavy traffic and sending it underground and out of the way. With only city bound traffic on the bridge we could reallocate a pair of its lanes to buses, and without heavy freight traffic we would have enough strength in the clip-ons to add the proposed walking and cycling path.
More excitingly, without any need for a link between the bridge and the other motorways we could tear down the Victoria Park viaduct and free up that corner of the city. The remaining Victoria Park tunnel could be reused as a two-way link for traffic through to Cook St, perhaps even taking the bulk of traffic off Fanshawe St. In any case we could almost halve the number of lanes through St Mary’s Bay, if those lanes need only enough capacity to service the city streets and not the motorway.
There might even be a case for demoting the St Mary’s Bay motorway to an avenue style expressway, a sort-of western version of Tamaki Drive extending from a revitalised Fanshawe St boulevard. Auckland’s city waterfront could then stretch right across to it’s natural anchor at the foot of the bridge. I can see it now: rows of leafy trees, a stretch of waterside grass, cyclists whizzing along to the North Shore, kids eating ice creams as mums and dad watch the comings and goings of the marina and the harbour.
This all sounds very good, positively bucolic even… but truth be told we’re not really getting much value out of this yet. Five billion bucks to get some bus and cycle lanes on the bridge and tidy up the waterfront? To be frank that is the sort of thing we can do anyway at a much lesser cost, we don’t need a motorway tunnel for that. If we really want to get value out of a harbour tunnel it has to carry public transport, and I mean proper high capacity and fast rapid rail transit. Nothing else is going to move enough people to swing the numbers. Adding a rail line to the motorway tunnel could triple it’s carrying capacity at very little extra cost, if only some space could be found inside the same pair of tubes.
If we look at NZTA’s most recent proposals we are actually talking about some pretty big holes through the ground. One of the issues with boring a tunnel like this is that motorway lanes are basically rectangular in cross section, while tunnel bores are circular. It’s very much a case of fitting a square peg into a round hole. In this case the round hole will apparently need to be about 15.5m in diameter to fit in a square peg 12m wide and 4.5m tall.
That’s quite a lot of tunnel indeed, and in fact some of it ends up wasted. I’ve clarified the labels there because they are too hard to see, but the bottom right corner of the cross section is simply ‘cement stabilised backfill’. In other words that is just a mix of concrete and dirt poured back into the tunnel to hold the road deck up. Could we not put this space to better use?
Closer inspection of the cross section reveals the sorts of things you might expect in a tunnel: lights, fans, smoke extraction ducts. But underneath the road deck there is also a sump area to extract water, and a cable tunnel to carry pipes and wires across to the North Shore. That cable tunnel is actually pretty big, about 4m tall and 3.5m wide, could we fit a train through there? Probably not one of our new electric trains, they’re a bit too big and their overhead power lines need more height. But I do think a more compact light metro vehicle would fit in comfortably, particularly as they have a low floor height and get their power from between the rails instead of an overhead wire.
This picture shows a Bombardier ART driverless metro train to scale in that same cable tunnel, nestled in under the road deck. Instead of backfilling the empty space under the road, I’ve used it to relocate the cable tunnel to one side. This could also double as an emergency exit, or an access path to whatever emergency system they would have to install in the motorway tunnel anyway.
Basically, it seems with a little rejigging of the layout of our big harbour motorway tubes we could also fit through a light metro line to the North Shore. Given that it’s the same pair of bored tunnels, this rail crossing could be tacked on for minimal extra cost.
Now I must say I am no civil engineer and I couldn’t confirm if this is actually feasible, but a quick looks suggests that we very well could get both three motorway lanes and a driverless light metro track into what NTZA were proposing to build for the motorway alone. The benefits of this would be immense.
Three motorway lanes can carry about 6,000 vehicles an hour at best, which at our occupancy rates translates into about 7,500 people. The light metro systems in Vancouver and Kuala Lumpur currently carry about triple that on each track at peak times, and can theoretically move well over 30,000 people an hour each way.
Stacking metro tracks in under the road decks could easily quadruple the person carrying capacity of a harbour tunnel, and one can only imagine what that would do to the cost benefit ratio. If we must build a hugely expensive motoway tunnel under the harbour, then a shared motorway and metro tunnel could be just the thing to make the numbers stack up too.
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I love the idea of the waterfront tidy-up. It’s great in places like San Francisco and New York to be able to walk/bike to the foot of the bridges, and on at least one of the ones in New York you can walk and bike over it too. I know you’re just suggesting something and that something like this may not happen, but this would be awesome and this blog is great and I just got really excited for some reason.
This idea of a dual tunnel is exactly what has recently happened in Shanghai. They built a three lane motorway tunnel with a metro line underneath the road deck.
I think that this it’s exactly the kind of thing that will will eventually happen and even if tracks aren’t installed straight away, it would be a huge advantage having the space ready to go as we are not likely to have much money spare to build a rail network of any kind after shelling out over $5b for the tunnel.
Nice idea. Only question that springs to my mind is how much of an issue it would be to have such a long stretch of single track?
Well presumably you’d have crossovers either side of the tunnel, so that would be some 2.5km without any chance to cross to the other track. Thats no worse than many parts of the existing network.
In any case this would be the same, Te proposals for separate rail crossings also have each track in a separate tube.
Bi directional signalling would take care of emergencies or planned closures.
It would be good if the tunnel could accomodate overhead wires as it would allow the same light rail systems to potentially be used Auckland wide (I can’t imagine we’d allow third rail down Dominion Road say).
The ideal scenario would be for the PT deck to be large enough to carry anything, then we can use whatever type is best suited to operating the route rather than potentially compromising the route to fit the infrastructure. I don’t really mind as long as it is fast and capacious and can be automated, although if space is right then third rail would be a big advantage.
Just a note on light metro through, the type I’ve suggested is very much a ‘proper’ grade separated driverless rapid transit system. That’s very different from the sorts of light rail tramway you could run on dominion Rd, and indeed light metro cannot be run in street corridors (except in a tunnel or elevated over the roadway).
Of course even cheaper still, just build the train tunnels. Especially because as commenter Mr Anderson recently put it; ‘it matters what you don’t build as much as what you do’. Six more traffic lanes across here will have an impact on mode choice, helping to undermine the utility of both buses + trains, and of course making them less cost effective, and the train line would also undermine the business case for the roads! This would be a huge spend in order to promote driving, where will all these additional vehicles go?, both on the rest of the motorway network and in the city? Any additional traffic lanes across the harbour create a huge knock on effect of additional spending throughout the whole city; parking; local roads; arterials; state highways.
To sell this idea they must argue that the bridge is and will remain full and that there will be demand for the new lanes- any new quick PT service will blow the already non-existent case for this spending completely out. Especially as we have proven PT uptake on this route.
Unfortunately all that might happen with this ‘multi-modal’ tunnel idea is that a space might be left for this possibility in the future but there will be no money to connect it to a new Shore line, especially as the road tunnels and motorways will be so expensive. This idea only has legs as PT wash.
Also there is nothing in the work to date that suggests anything like a reduction of motorway space at St Mary’s Bay or anywhere else in Auckland: http://awhc.nzta.govt.nz/eBooks/Volume%202%20%20-%20Drawings%20October%202010/
In fact it looks like they want full interchanges at each end of the tunnels!?
Wouldn’t down-grading the Bridge to a local route mean that the Council would then be lumbered with its upkeep? If SH1 is now this expensive [and expensive to operate] tunnel, who get’s to manage the bridge?
Would either or both be tolled?
If this is what multi-modal means: 18 vehicle lanes across the harbour, I think some people need to get a dictionary and look up the words multi and modal.
Indeed Patrick, just building the train tunnels would be the ideal situation and by far the cheapest and most effective option. But unfortunately just building the motorway tunnel is a far more likely outcome. I’m just trying to be pragmatic and seeing what we can do to make the best of a less than ideal situation. I do realise existing NZTA plans don’t reduce St Marys Bay (indeed some fill it with a ghastly interchange), but they don’t include rail links or anything else either. The reason St Mary’s currently splays out so much isn’t for lane capacity, but rather the junction functions that occur here to divide city and state highway traffic. If we relocate the state highway link through to the CMJ then the most St Mary’s would ever need to carry is the eight lanes of the bridge, not the thirteen odd we have today.
My suggestion would be to have the six tunnel lanes carrying SH1 from Onewa underground all the way to the Wellington St overbridge, and connecting only to SH1 south and SH16 west and east. This would allow us to remove the motorway between Victoria park and Wellington ST, and to rebuild and reconnect the lower parts of Freemans Bay. Separate tunnel and bridge onramps and Onewa and Akoranga would negate the need for a huge interchange. Meanwhile on the bridge we could allocate the two outer lanes to buses and traffic for Curran St/Shelley Beach only, so they would be mixed on the bridge itself but traffic would be exit only at Shelley Beach (buses would continue in a bus only lane to Fanshawe). The other two clip-on lanes would link general traffic through to Fanshawe St. Of the inner four lanes, I would actually remark these as three full size lanes. This purpose is two fold, firstly to make them normal sized (i.e three 3.5 lanes plus shoulders rather than four 2.9m lanes), and secondly because these three lanes would carry through St Mary’s and into the three lanes of the Vic Park tunnel.This would be complemented by extending the movable barrier (or returning to lights) to tidal flow the centre lane all the way to Cook St, so that there would be two lanes in the peak direction and one in the counter peak. Effectively this is shifting some of the city traffic priority away from Fanshawe and over to Cook St, the idea being to make the waterfront area less car dominant (albeit somewhat at the expense of Cook St and Mayoral Dr). So St Mary’s could have seven lanes: a bus lane each way, a Fanshawe St lane each way, a Cook St lane each way plus an extra peak lane to Cook.
If they do build this thing then we need to propose some more innovative solutions and demand better urban design outcomes otherwise we’ll get just another motorway quagmire.
Curiously it would be in the best interests of the network to keep the tunnel and bridge flows entirely separate, any traffic engineer could see that. There are opportunities to prevent such a tunnel undermining public transport, the main one is that it will almost certainly be tolled which gives us the chance to price and manage access accordingly. From a traffic perspective I see the value here as more like separating the traffic flows and keeping the state highway track underground and out of the city. As you quite rightly point out there isn’t capacity on the rest of the motorways or city streets to have fourteen full traffic lanes across the harbour and almost zero opportunity to widen through the CMJ or city streets. This tunnel simply can’t be about huge capacity expansion, whatever NZTA say’s it needs to be more about space allocation and efficiency.
Interesting idea – are you suggesting the road/rail tunnel entrance should be Grafton Gully, to reduce congestion at Victoria Park? I thought this had been looked at already?
No, I was suggesting that a) The tunnel takes the motorway traffic right through to Spaghetti Junction south of Wellington St and b) The Victoria Park tunnel could then be used to link the harbour bridge to Cook St in both directions (with tidal flow on it’s three lanes). This would give two general lanes to Cook St and one to Fanshawe at the peak. It also means there would be no need for any lanes on the bit between the Vic Park Tunnel and Wellington St.
Speaking of Grafton Gully and that idea Cameron, it been totally ruled out and if so why?
Due to the even more extreme cost, the tunnel would be significantly longer and a lot of works would be required in grafton gully.
Why not simply enlarge it enough to enable real trains to run under the deck? More cost, but the combined BCR should be massive, and we wouldn’t have to add another transport system to the mix. Of course if we got a REAL waterfont / citywide tram system out of it, I would be happy to agree to serving North Shore with light rail.
As for the “a motorway tunnel will be built” pessimism – that will only happen if National gets reelected at least one/two more time(s), so still a way off. But no reason not to think about efficiencies anyway, as this article did. Good stuff.
What do you mean by ‘real trains’? The automated light metro I’ve suggested actually has more capacity that our EMUs will have, and allow much greater frequencies to. Check this link for my discussion of the technology: http://greaterakl.wpengine.com/2011/10/17/art-light-metro-an-affordable-solution-for-new-rapid-transit-in-auckland/ ANd for reference here is a little picture of the vehicle I’ve inserted into the diagram above: http://skytrainforsurrey.files.wordpress.com/2012/02/20080901_rapidkl_4-car.jpg?w=610 . If you’re talking about light rail tramway then that’s really a totally different thing.
Our heavy rail EMUs will actually have a few drawbacks for a line to the shore. The way I see it is we have the opportunity to build metro here and avoid those main line constraints. I’ve got no problem with another transport system in the mix, if it is better suited and more efficient.
Well, okay, strike the “real trains” then, and replace it with “heavy rail”. I can see the point about horses for courses, but I remain sceptical that we need more systems, even if there are some efficiencies in it, there are also disincentives. Especially if we intend to also have a tram system, which would then create three different rail systems.
Why bother saddling what should an operationally self contained line with all the constraints and compromises necessary to run on the national network? Adds billions to the cost for something that’s lower quality and more expensive to operate…
I forget the name of the report but the numbers were crunched by one of the large engineering firms in a report less than two years old.
Basically if you want full blown heavy rail and motorway it is cheaper to build two completely separate sets of tunnels than to try and integrate them.
The main reason is that (heavy) rail tunnel must have a very flat grade. A motorway tunnel can handle a much steeper grade but is much more expensive to build per meter as it requires much more advanced services (lighting, fire and especially ventilation to get rid of all the fumes).
As such it was deemed to be cheaper to build a short motorway tunnel and long flat rail tunnel than a long flat rail/motorway tunnel.
Getting heavy rail alignment to meet the city portal is also a major issue.
Also note that overhead wire heavy rail needs a really tall space. – I would guess nearly double the height of the vehicle depicted by Nick R
I’d vote for a “small” bridge linking North Shore to the new SH20 at Point Chev so all the north-south “through” traffic can bypass the cbd/spaghetti junction completely.e
Possibly pay Chelsea Sugar to relocate their factory elsewhere so a lower bridge could be used.
Then a rail-only tunnel to the North Shore.
We shall fight you on the beaches… well, on the beach anyway and maybe from the sharp end of Coyle Park.
Yeah I’m not sure if a 2km tunnel under Pt Chevalier linking into a 4km bridge across the harbour and then into 6km tunnel to connect back to SH1 or SH18 could be considered “small”. I’d consider that absolutely ridiculously huge actually.
I know you’re trying Nick, but doesn’t it feel a little like putting lipstick on a pig? I have a hard time trying to find any redeeming features in a project that only seems destined to induce further traffic congestion when there are potentially cheaper alternatives available (like a transit-only second crossing).
At central government level there seems to be this implicit assumption that all motorway projects should go ahead until it can be categorically proven they shouldn’t, while all rail and public transport projects shouldn’t go ahead until it can be categorically proven they should. “Well we should build more motorways because everyone drives!” “And why does everyone drive?” “Because we spent decades building more motorways!”.
I’ll just point out that Vancouver’s North Shore municipalities (combined population ~178,000) are linked to the rest of the Greater Vancouver by one six-lane bridge carrying the Trans-Canada highway (located nowhere near downtown) and a three (!) lane bridge next to the downtown peninsula. Makes the ferry very popular…
Exactly, Icebird. And here, even the Daily Telegraph has woken up to the fact that we [OECD] are getting the priced out of the petrol market: http://www.telegraph.co.uk/finance/commodities/9122311/Plateau-Oil-meets-125m-Chinese-cars.html
Insane to be even considering building more road vehicle dependent transport systems in a city that is so rich in them. The only way to get toward multi-modality in Auckland is to urgently prioritise the missing modes: And for the harbour that means: walking, cycling and electric powered transit. As it does everywhere else.
I’m not in favor of a motorway tunnel Icebird, just trying to make it not totally suck if one was built. I wasn’t looking for redeeming features in it, I was trying to work some in!
Would the cheapest rail crossing be a pair of tracks inside a round tunnel, with a central dividing wall for safety?
Assuming overhead power, the conductors could be offset towards the dividing wall to reduce diameter?
Using the same rolling stock as the rest of the network would have advantages in scheduling and maintenance.
If they weren’t overhead power, so long as they used the same rail gauge they could still be shunted to a service yard on the current rail network.
I suspect that there is some intention to use the Earth Pressure Balance TBM purchased for the Waterview Tunnels also for the cross harbour tunnel(s).
Shanghai Tunnel details:
http://www.bettertransport.org.nz/forum/viewtopic.php?f=1&t=2597&start=200
The Waterview TBM is about 100mm bigger diameter than Shanghai.
Two small tunnels are usually cheaper than one large one. As a comparison, a pair of 4m tunnels would have the same volume as a single 6m tunnel, and half the volume of a single 8m tunnel.
I think evacuation requirements favor twin tunnels everywhere where running regular stairwells to the surface is not an option.
Actually the Waterview one is smaller, it is about 14m vs over 15m for the Shanghai tunnel.
Is saving $5B by running light rail across the centre lanes of our current bridge still the cheapest option?
I’m thinking the tunnel builders and the motorway builders are the same people.
If we don’t have one, we won’t have the other yes?
I’m pretty sure running buses over the clipons is still the cheapest option!
Ok, I’m with Nick- unless the Shorians really, really want light rail- the buses will do it.
Now what do we spend the $5B on?
Well if you follow the first link on the post, there is an indication we could build a rail tunnel plus a whole metro system on the shore for well less than $5 billion.
Buses over the bridge are doing great now, but we’ll need something more at some point. A bus or light rail bridge would be the cheapest option, but many folks don’t want another bridge. After that would be rail tunnels (about $1.5 billion) then the motorway tunnel which leaps ahead to $5 billion. Road and rail would be an eye watering $7.5 billion.
However if they insist on building the motorway tunnel regardless, then the marginal cost of adding in these compact light metro tracks would be cheapest, even cheaper than a basic bus bridge.
By comparison, the latest LU Victoria Line trains are 2.9m high by 2.7m wide. They’re proper trains and there would be enough room to run these through the described tunnel. One question though… how much space do you typically have to allow between the train and the tunnel walls to account for train wobble and tunnel curves? I don’t think you can count on a completely straight tunnel… if nothing else there are bound to be curves to merge road and rail at the portals.
Oh, and another question… Why is the road surface on a slope? Surely there isn’t going to be enough seepage in to the tunnel to warrant runoff?
In a tunnel like this I assume that the rails would be attached directly to a concrete pad at the base of the tunnel so there would be very little movement (this is what they have done at New Lynn with the trench).
Deep tube trains in London are a bit bloody cramped if you ask me, but it is a good example of what can be done in very tight spaces. The skytrain vehicles I’ve used above are only 3.3m from roof to rail and have a lot more headroom. One of the benefits of their linear induction power is that they need much lower floors and can run smaller wheels without conventional hub motors.
It does look like they’ve planned for plenty of water with that sloped floor and big sump.
Great idea and yes to the Linear motor trains. Keep the tunnel going all the way under Auckland with a stop at Wynyard Quarter, the proposed Aotea station, Auckland University and terminating under either Parnell station (with connection) or re-introducing the old beach road station as a national rail station (Hamilton…) and you’ve got a very good rail network (with the CRL of course). Also very much liking the St Mary’s Bay idea of taking away some lanes for green space. Permanent bus lanes on AHB too!
Just make the tube bigger! Or instead of drilling 2 tubes, drill 3. Two for motorway, and the third for rail. If we ask the Chinese nicely we might be able to buy 2 for the price of 3, and get a free set of steak knives.
Drilling a third tunnel would add about 50% to the cost, likewise with making them bigger. But why bother when there is already wasted space in the tubes they have planned? Looks like about 1/8 of each tube is just going to be filled with dirt again!
Put a hefty tax on inner city car parks that are currently provided free by employers.
That should cut traffic on the bridge eh!