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Guest Post – Driverless Light-Metro: The Dominion Line

This is a guest post from reader Axio

Peter’s post on the future of driverless light-metro got me thinking about whether there are alternative alignments where an automatic metro could be used, and I felt that it would be a cost-effective solution to mayor’s vision of rail to the Airport and the North Shore.

Many proposals presented in this blog focus on connecting a North Shore line with the City Rail link by crossing at right angles at Aotea station and tunneling under the university to come out somewhere on the Eastern line. This minimizes the additional infrastructure needed on the city side of the link. However tunnels are very expensive and if an elevated metro is used then we might find that we can achieve much more substantial system for a similar cost.

This alternative considers a line from Takapuna through to the Airport. This would be a driverless metro elevated along its entire length, except possibly the harbour crossing. The proposed alignment is illustrated below.

 

The benefits of this alignment are many:

Obviously this provides rapid-transit to the North Shore, Mangere, and the Airport, meeting the strategic goal. It brings Takapuna onto the Rapid Transit Network (RTN), which is useful as it has been identified as a commercial centre in the Auckland Plan. This also makes the CBD much more accessible from western South Auckland.

  • Leverages the most effective part of the Northern Busway by providing a high frequency connection at Akoranga. If most buses terminated at Akoranga then the lowest capacity and slowest section of the busway (the harbour bridge and CBD) would not be required for the bulk of trips.
  • Replaces overcrowded bus routes on Dominion Road, and in doing so takes the pressure off Symonds Street. It also allows Dominion Road to retain its on street parking which was a sore point during the submissions into Light Rail on the corridor.
  • Connects into the existing rail network at Onehunga and Mt Eden (depending on where stations are placed following construction of the City Rail Link).
  • Provides another access point to Eden Park along Bellwood Avenue.

And overall it brings together parts of Auckland that are presently quite separate as far as transit is concerned.

For automatic metro the line requires its own right of way which would be achieved largely using elevated rail. As most of the line is above road corridors, this would require a viaduct composed of single columns about 4.5m high with the rail deck around another metre higher. Stations would be spaced every kilometer or so. As mentioned earlier the harbor crossing may be tunneled, and the section along SH20 could be at ground level in places.

There are some challenges inherent in the alignment and terrain. The section east from Hillsborough Road to sea level will be quite steep and probably require a viaduct that extends well east of where SH20 flattens out in order to reduce the gradient. Similarly the section through the CBD will be quite steep, although with a station in the middle the slow speeds due to gradient will be less painful to passengers. Getting through the CMJ can be done using the old Nelson Street off ramp from the Southern Motorway followed by a viaduct over the CMJ once clear of K-Road. The corner at Wellesley and Hobson is quite tight, although the radius exceeds the 35m mentioned as the limit for this type of metro as shown.

This brings us to the big question: what will it cost? In this case I will just look at the section from Wynyard to Onehunga as costings for heavy rail north and sound of there can be found in other documents and provide a reasonable indicator of cost (particularly to the north where the cost is largely due to the tunnel).

The Vancouver Skytrain provides the most useful estimates as it is the system on which this is based. South Fraser Blog quotes On Track: The SkyTrain Story which indicates the cost for the elevated only section is around $47million per kilometer in 2012 Canadian dollars. At the present exchange rate this comes out to about $60million per kilometer so the line from Wynyard to Onehunga, at around 14km, would have a baseline at $840 million. Building above a road corridor would likely increase the cost, and we also have to deal with the special viaducts at the CMJ and Onehunga. Finally that estimate does not include the cost of the trains.

Compared to the Waterview Connection and the City Rail link this project, at a little over a billion dollars, is relatively inexpensive given the area it provides service to, although obviously much of the benefit would come from the un-costed sections from Wynyard to Takapuna, and Onehunga to the Airport. It does also have the ability to be built in sections with each section providing significant benefits on its own. For instance Wynyard through to Bellwood Avenue would provide a different place for Dominion Road buses to terminate, and still connect the Isthmus and West to Midtown and Wynyard.

The cost not-with-standing, an elevated metro has a significant downside, visual pollution. A 5.5 metre viaduct will stand-out in all but the CBD, and as Dominion Road has something of an iconic status this visual pollution may be unacceptable. There are alternative corridors through the isthmus such as Sandringham Road which would have the benefit of being closer to St Lukes, a major attractor, but increase the overall cost and the journey time from the North Shore to the Airport.

Finally, while this line is intended to complement the City Rail link, it does have potential to stand on its own, providing rapid transit access to Midtown from the central slice of the city (from the Airport to Albany) and the West, assuming a transfer at Mt Eden. However it would not be connected to the East of the city, and so its benefits would be reduced without the City Rail link.

 

18 comments to Guest Post – Driverless Light-Metro: The Dominion Line

  • Interesting, but fantasy-land with the costing I fear. Does that include stations? And while I think elevated lines can be dramatic I suspect the citizens and shopkeepers of Dominion Rd won’t share my view. No K’rd station?, that seems a shame or is there really not enough space there? Probably not. I know that abandoned motorway lane just looks like a free route but each end of it is at grade with cars so it would actually be more than a little tricky to get into and out of.

    • axio

      I’ll be the first to admit I’ve no idea what the total line might cost. What I’ve got is information based on a similar system and extrapolated it. I believe that information includes the cost of stations, and is also from a seismic area so I wouldn’t expect extra costs for that reason. Cost is obviously a huge consideration, but the main aim here was to put an alternative on the table that meets multiple strategic goals.

      As far as the CMJ bridge: there’s about 100m from the K-Road over-bridge to SH1 Northbound. Assuming the need to get 5m clear requires a gradient of 1 in 20, which is within capability of the train. I agree it would be nice to have a stop a K-Road as well. It’s presumably be quite easy to access from the over-bridge and provide great linkage into a lot of buses.

  • Liam W

    Very elegant in that it connects two important points not on the RTN via a corridor that is already very popular and will need more capacity. Also elegant in that it utilises the light-metro technology/cost benefits without having an orphaned North Shore-only system or having to replace any existing heavy lines with light metro. That alignment makes alot of sense to me. If only elevated lines weren’t so pig-ugly and therefore infeasible…

  • Luke

    There are big benefits to driverless metro in the right corridor. However an urban shopping street like Dominion Road is not the right place as effects will be dreadful. Light rail is perfect for this corridor as does not consist of nodes but continuous activity so needs closer stop spacings. The North Western Motorway is right sort of place so too is pakuranga highway and Te Irirangi Drive.

    • axio

      One of the benefits of a light metro is increased acceleration time which allows stops to be placed more closely together than they could be on a heavy rail line with less impact on performance. There is also no reason why local buses couldn’t continue to operate along Dominion Road, connecting to stations – this would probably suggest having less stations.
      Ultimately the goal is to unite the North Shore and Airport lines, and Dominion Road provides a fairly direct routing to achieve this.

  • bbc

    You only have to look at the areas of Vancouver where they have their elevated skytrain to know that whilst they’d blend into a lot of the areas that for instance the Southern Line run through no problem, or the Northern busway for that matter, they don’t mix with more fine-grained development such as that along Dominion Rd. Several areas look like the wasteland that is left behind when an elevated motorway is built through somewhere.

    I also tend to think that Dominion Rd is somehere where people will want to get on and off frequently to access shops and hence a tram ois ideally suited, rather than a skytrain type system.

  • Matt Clouds

    One thing to be wary of is having elevated structures crossing Greenlane/Balmoral Roads, as they’re part of the designated over-dimension corridor. If you look at them, they’re completely free of overhead wires and other obstructions.
    Getting consent for any project like this would require either constructing a very high span or, more likely, tunnelling beneath that corridor. That pretty much destroys the costing, and a lot of the possibility of getting permission for that routing.

  • Joshua

    Great Idea, just not right for Auckland.

    Along this route we need light rail, for rapid transit it’s going to have to go underground in my opinion. Auckland will get there, but it’s going to be a while before we start investing in underground rail, the significant cost implications will put this on hold until our population significantly increases. Unfortunately with a sky train type system we can end up having the same visual effects of a viaduct motorway system, ugly. CRL will be the first underground rail, I wouldn’t expect more until around 10-20years after that.

  • Icebird

    I just can’t see an elevated sytem along Dominion Road getting much support. The road is too narrow, and the guideway would be too intrusive. The closest equivalent in the Vancouver System is Cambie Street, where they elected to tunnel rather than build an elevated system. The Canada Line is only elevated south of the Fraser River, where the guideway could travel down the middle of some very wide boulevards in Richmond (I think they took over some bus lanes in the middle of the road).

    A driverless rapid transit built along the Northern Busway alignment is low hanging fruit when it comes to infrastructure. The major obstacles are crossing the bridge, linking the system to the CBD, and perhaps the spur to Takapuna. By comparison, a system along Dominion Road will be either very expensive, very intrusive or potentially both for the entirety of its length. There’s also an element of duplication with the existing rail lines. If you were to build an elevated rapid transit down Dominion Road, does-not-yet-exist completely-unproven-in-the-real-world high-capacity PRT would be cheaper and moderately less intrusive.

  • Dominion Rd isn’t the place for this type of infrastructure, the cost and impacts of elevated structures would be immense. Skytrain in Vancouver required a 2.3m diameter column every 37m, and the guideway is 8m wide while stations are 16m wide.

    Dominion Rd is only 14m wide kerb to kerb in most places. An elevated structure would require a central median about 3m wide (reducing the street to two lanes and no parking), while the guideway would basically box in the street. Dominion Rd would become a concrete tunnel.

    There are plenty of places where this technology could be of great use at ground level and other places where elevated lines could be acceptable, i.e. the Northern Busway, the Northwestern Motorway corridor, the Upper Harbour motorway corridor, The Southwest Motorway Corridor and Te Irirangi Dr.

    Downtown and Dominion Rd aren’t those places.

  • axio

    I appreciate the visual impact is a killer, and I wasn’t aware of the over-dimension corridor. Perhaps if nothing else, such a proposal would make light rail seem considerably more appealing. Regardless, I believe this would be a valuable line to follow the City Rail link if the appropriate and cost effective technology could be found.

    While researching this (and alternatives) I had a great deal of trouble finding indicative costings for various technologies. I appreciate that the environment and requirements (soil makeup, existing services, size/clearance/tunnel depth) has a massive impact on costings, but have people found useful sources to get estimates of cost per km/mi for the various technology options? In particular I wanted to look at what a cut and cover tunnel would cost given that a tunnel for a rail system has the benefit of being much smaller than a road one.

    • Estimating construction costs of major infrastructure based on overseas experiences is very difficult, it is far too dependent upon the specifics of the situation and you can be a whole order of magnitude off if you get that wrong.

      Whether you’re building a busway, tramway, light metro line or heavy railway the cost will be largely the same if you build to the same standard. Apart from the easy curve and grade of bus/tram/light metro vs. heavy rail you need much the same width corridor and structures regardless of the technology employed. So the cost differential is mostly down to whether you have something running on street, elevated or in a tunnel, not whether that something is a bus, tram or metro train.

      I think the second part of this line is worth investigation for driverless rapid transit (from Onehunga to the airport), but the Dominion Rd section should stay as a street level solution either as BRT or trams. Once we cut out hugely expensive concepts like elevated or tunnel then they obvious end solution for Dominion Rd becomes street level light rail trams in dedicated lanes (the only real reason I pick trams over buses is that Dominion Rd is a narrow corridor and trams can operate very effectively in a 2.9m wide lane, with BRT buses you really need 3.5 to 4m to run them efficiently).

      Sure that writes off Dominion as a strategic corridor but there just isn’t any opportunity to build one.

  • I doubt this would be any cheaper than the connection of the existing line west of Parnell to Aotea Station, and on to the Shore. Yes tunnelling is expensive, but this involves a relatively short one with relatively few connections. Building underground stations is really the expensive part and this line could be done with two shallow stations; new platforms at Aotea, and one at Wynyard that both would be cut and cover, way cheaper than tunnelled ones. Also the line from the harbour crossing to Aotea would also probably be cut and cover.

    Dominion rd clearly needs an at grade solution, as well as relief from longer journeys passing through it which the Avodale corridor can provide.

  • rodin

    @Icebird – The Canada Line is a mixture of bored tunnel, cut and cover, viaduct and some at grade on the YVR spur. The cut and cover section along Cambie St required trenching across almost the full width of the 6 lane road corridor which is generally about 26 metres wide including footpaths. 2 of the lanes (one each direction) were usually kept open during construction but disruption to the businesses along Cambie was high and has resulted in a number of ongoing lawsuits. At some point in the (hopefully soon) future, the Millenium line will be extended to UBC, along Broadway, which is another 6 lane arterial. There is heavy pressure for this extension to be a deeper and more expensive bored tunnel to avoid the construction disruption again.

    Dominion Road in most places isn’t wide enough for a cut and cover trench to accommodate twin skytrain tubes – you’d have to temporarily remove many of the buildings on one side of the street. As well, the road would need to be entirely shut down to all traffic for a year or two during the construction phase.

  • KLK

    I take the light metro (“LRT”) here in KL on occasions. I drive under it at some point most days. Its a great system to ride, its a blight on the landscape though and its only going to get worse with the (albeit necessary) extension/MRT project.

    Perhaps there are places it could operate (people have suggested the busway and the NW motorway) but really, I think these sorts of elevated options need to be retired.

  • Anthony

    Overhead power lines for any at grade solution would also get in the way of the overdimension corridor.
    The only likely solution at this point would be a tunnel.
    Grade separation would be good anyway.

    How far would a tunnel extend each side of the intersection?
    Stop/station location?

    • Matt Clouds

      Overhead wires can be dealt with, because they can be temporarily disconnected to allow an over-height load to pass. Those kinds of vehicles already only travel in the small hours, so there’d be no disruption to service, and even if we get to the point of having 24-hour services we’re only talking about a one-hour disruption on a very, very infrequent basis.

      Over-dimension permits are issued for specific routes and under specific conditions, and it would be trivial to require compensation to AT (or whoever) for providing appropriate personnel to handle disconnection of overhead traction wires.

      Structures, however, cannot be so easily removed from the path.

  • Luke

    also I bet a small battery in the LRT vehicles would also do the trick.
    I heard somehow that most new LRTs have this feature anyway, so they can move a few around a depot or even through town centres without adding wires.

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