The topic of rail to the airport has been getting an airing in the last few weeks after the Herald finally published some information we originally posted back in August – that AT are considering using light rail to connect the airport with the city rather than extending the heavy rail network. The need for a decision on what mode to eventually use is being hastened as the airport company need it by the middle of the year so they can finalise their future development plans. We’ve got an exclusive video showing what the heavy and light rail options.
Before diving into the details I want to make a couple of comments.
- Unfortunately much of discussion I’ve seen in the wake of the articles has fallen into the trap of being too focused on the technology rather than the outcome and despite the focus there appears to be a general misunderstanding of the technology involved. By that I mean there seems to be an assumption that light rail is a low strength version of heavy rail, a bit like light beer vs normal beer. In reality it all depends on how each technology is implemented. There are light rail systems that are faster and have greater capacity than what our heavy rail system will have even with the CRL.
- I’ll state upfront that my preference remains that the connection be by heavy rail. I think the time competitiveness it offers is probably being undervalued by AT compared to the other factors. I also see it as a nice balance to the operating patterns proposed post CRL. In effect I see it as completing the heavy rail network.
- AT have already decided that the connection to the airport will be from Onehunga linking in Mangere Bridge and Mangere. Onehunga is also important is has been chosen by Panuku Development Auckland as one of the key areas they’ll be focusing on and so improving connections from their in either direction makes a lot of sense. The alternatives of connecting via Otahuhu have been ruled out due to the amount of property purchase that would be needed and the Puhinui option would require difficult (i.e. expensive) connections and would be a challenge operationally.
So why are AT even thinking about light rail. The simple answer is the cost. AT say that they now believe it would cost around $2 billion to build a heavy rail line to the Airport. Light rail is cheaper and easier to build with AT have estimating it at around $1 billion – but importantly that is from the end of the proposed line down Dominion Rd. AT seem pretty confident they’ll get that line signed off but whether that turns into a reality remains to be seen. However even if you take the $1 billion cost for a light rail line down Dominion Rd into account you’re still looking at a $2 billion heavy rail line serving just the southwest or a $2 billion light rail line that serves the southwest and the central isthmus. As such, on a cost/benefit comparison the latter is going to look stronger and why AT is interested.
To help show some of the differences between the two options AT have put together a fairly detailed video of them which is at the end of the post. I first saw this over a month ago and AT have now let me post show it. It was included as a part of the presentation that inspired this post. There is no narration to explain what is going on so I’ve explained it below. I understand AT are working on a narrated version for wider public use.
The video starts off showing the potential travel times between the city and the airport. Along with the time it takes is the potential variability and in that regard the rail options offer more reliable trip times than buses and much more reliability than driving. As I understand it the reason light rail is more reliable than buses is that it will have effectively an exclusive right of way down Dominion Rd combined with signal pre-emption meaning it will rarely need to stop at lights. That it might need to stop has been an issue raised against using light rail and is a case of perhaps AT not explaining clearly enough just how high the quality is that they’re proposing.
It’s also worth noting that the travel times suggested are more in line with what we’ve posted before and not as close as the herald has suggested, around 35 minutes for heavy rail and 47 minutes for light rail (herald suggested 39 and 44 respectively).
The video shows the heavy rail option. It involves double tracking the Onehunga Line and as I understand, grade separating many of the crossings. It then follow SH2o and 20A with stations at Mangere Bridge and Mangere and then crucially it would loop away from SH20 before getting to the airport itself. This is important later in the post.
Light rail would travel from Dominion Rd alongside SH20 to Onehunga and then on the same route to the airport with the exception of it staying with SH20 the entire way. In addition to what’s proposed above there would be stations at Hillsborough, Favona, Ascot and the Airport’s growing office park. From the end of Dominion Rd the 15km line to the airport would be almost completely grade separated and so would have similar performance to heavy rail. That makes the line roughly 1/3 on street and 2/3rds off street. I’m not quite sure why there couldn’t be heavy rail stations at Favona and Ascot but there definitely couldn’t be at the airport business park as the route avoids that area. The extra stations help increase the catchment in favour of light rail.
The video gets more interesting once it zooms in to show how the lines would look. Between Onehunga and the SH20/A motorway junction both heavy and light rail have virtually identical infrastructure. A bridge would span the proposed East-West Link that then passes under the motorway bridges to the western side of the motorway. From there it travels alongside the motorway rising over the Walmsley Rd/Corronation Dr interchange before rising again above SH2o. It’s from here that the differences really begin.
After crossing above the motorway the grades required for heavy rail mean there isn’t enough space to get back to ground level before reaching Bader Dr so the Heavy Rail option is elevated above it to the Mangere Station.
The same issue then occurs with Kirkbride Rd and the trench currently being built meaning the line then has to pass over Kirkbride Rd. I understand the trench is about two times too steep for heavy rail.
South of Kirkbride Rd the line returns to ground level but has to divert away from the road before reaching the airport. As I understand it all transport options will need to drop below the second runway that is proposed and again the grades mean the rail line can’t follow the road.
Lastly for some reason it’s been decided that the heavy rail line and the station has to be underground at the Airport, this obviously pushes up the cost of building the line. I also understand it has been proposed to be located a little further away from the terminal than the light rail stop at street level and the extra walking time has even been factored into the travel time calculations. Given the airport is planning a fairly blank slate redo of the road network all around the airport and building an new terminal extension, it seems strange that a heavy rail route and station at ground level couldn’t be easily integrated into masterplan.
Light rail is able to handle steeper grades and sharper curves than heavy rail is and as such is able to get back to ground level and go under Bader Dr. This means a light rail station would be located within the median of the motorway – and hopefully with some good noise protection. You may notice the station planned is much less glamorous than its heavy rail counterpart – presumably making it much cheaper.
South of the line is able to stay within the motorway median and pass through the trench currently being built and for which AT have paid $29 million to make 3.5m wider so it can accommodate rail. I’m sure visually for locals and from a consenting perspective this will be an easier sell than the elevated heavy rail option. Light rail is then able to stay with road all the way to the terminal again helping to keep it cheaper. It seems the main benefit of LRT is it’s just that much easier to bend around existing infrastructure.
AT then give a comparison between the two modes showing what they think is best. This is similar but not exactly the same as one shown in the August post. For one thing it lists the benefit cost ratio of each option suggesting that some likely early economic evaluation has already taken place. As you can see the light rail option is quite a bit higher than the heavy rail option although it is only hovering around 1 – much like many of the RoNS.
Here is the video.
The two biggest arguments against light rail seem to be the speed and capacity. I think the speed one is warranted to a large degree as I suspect offering a rail option that was almost always faster than any road option would have a huge impact on what mode people choose to use.
As for capacity I suspect that one is a bit less valid – although not completely. AT are suggesting some very heavy duty light rail vehicles capable of carrying up to 450 people each and on a route like Dominion Rd they would be running fairly frequently, potentially every few minutes if places like Melbourne are anything to go by. That is a considerable step up the capacity of buses along there now, although looking at the comparison table above they seem to be underselling it as 1,630 passengers an hour works out to only four vehicles an hour each way. The question is whether the additional patronage generated by a southwest line would then result in issues along Dominion Rd which is busy enough as it is. It would be good for AT to cover that issue in more detail.
If the figures above are accurate it’s easy to see why AT are so interested in light rail. In the current political climate it would be impossible to every get a heavy rail option over the line, it’s just too expensive. Light rail appears to be far from completely terrible and actually has a chance. A case of don’t let perfect be the enemy of good? In saying that I do get the feeling that there’s a little bias going on. For example why aren’t there extra heavy rail stations at Favona and Ascot.
What do you think of the options?
Lastly regardless of the mode, if drivers are anything like the ones in the video I think rail will be a huge success – although perhaps that just represents reality.