Last week I wrote about how the impact of speed on our transit networks. I showed that just because one vehicle might have a higher top speed than another on paper, that it doesn’t necessarily mean it will be much faster in reality. A lot depends on aspects like acceleration and station spacing, for example, over 2km there is just a four second difference between one of our trains with a maximum speed of 110km/h over one with a maximum of 90km/h.
To come up with that result I created a model that uses the acceleration and braking profile of our trains to estimate how long travel would take between stations, based on the distance and the maximum speed allowed. I originally built it to look the various travel time options that will be available for trips to the airport, to test just how accurate the claims were by Auckland Transport of light rail, that many have questioned. I was also inspired by Transport Minister Phil Twyford’s comments at the launch of the Manukau Bus Station where talked about the network that will be built.
We’re going to build rapid transit network, starting with light rail from the city and across the isthmus and out though Mangere. It’s going to deliver 21st century rapid transit to a swathe of our city, and it will stimulate a massive surge of private sector investment in urban renewal that will create more affordable housing and a better built environment for so many of our people. Alongside that immediate priority, we’re going to run rapid bus services connecting the airport, Puhinui and Manukau, giving everybody who’s served by the heavy rail network right across our city, rapid transit access to the airport and all the jobs out here in South Auckland. That airport to Puhinui link will be the first step in a rapid transit link serving the south east, which is even worse than my beloved West Auckland when it comes to being served by public transport. So when you put those, the light rail, the south east rapid transit line alongside extension of the Northern Busway, electric rail to Pukekohe, you have the trunk architecture of a rapid transit system, and around that, you put the high frequency bus services, and ferries to support that rapid transit. Within a generation folks, we’re going to deliver Auckland a world class public transport system.
In this post I look at those airport options. It takes the modelling in the last post a step further by adding in multiplier factor to account for the fact that conditions aren’t always perfect, that there are hills and curves which may not be able to be negotiated at the top speed, and included dwell times at stations. So travel time + multiplier + dwell time.
Before getting into the airport comparisons, I first wanted to calibrate the model against our existing rail network. I plugged in the distances between each station, what I understand the maximum line speeds to be – although around the approach to Britomart to reflect the approach to Britomart being slower. For the dwell times I’ve used 50 seconds as an average dwell time based on my personal observations, with the exception of Newmarket for the Western Line. I then adjusted the multiplier to get the times similar to what the Auckland Transport timetable says. For this the Western Line is slightly higher which is understandable due to the extra hills, curves and level crossings.
The next step was to think about what the trains should be capable of after the CRL has been completed, and assuming Auckland Transport manage to speed up trains, both through dwell time and other network improvements. For most stations the dwell time drops to 30 seconds with slightly longer allowed at larger stations. The travel times are also to Aotea given it will be the heart of the network. Of course, the Western Line is the big beneficiary here with travel times dropping substantially. For example, New Lynn would be around 21 minutes from Aotea while Henderson is about 33 minutes. Those times start to become competitive with driving at most times of the day once you factor in things like parking. You may also notice those times are slightly faster than City Rail Link advertise, but given how conservative their comms have been over the level of improvement that project will deliver, that’s not surprising.
Airport Light Rail
As mentioned, looking at the travel times to the airport was a key reason for building the model. Auckland Transport have claimed that light rail should be able to reach the airport from the city in 45 minutes and much of the opposition to it questioned this, focusing on the fact that on Dominion Rd the speed limit is 50km/h. They also miss that in the city centre on Queen St, the speed limit is just 30km/h. But to quote an old sporting cliche, light rail is a route of two halves. Once it reaches SH20, the station spacing opens up and so would the speed limits. So, I plugged all of that into the same model as above and the results were surprising.
Even with the slower speed along Dominion Rd and the more frequent stations, the calculations show that boarding light rail in the middle of the city, it should be possible to get to the Airport in just over 42 minutes. In other words, ATs estimation is correct.
The very first rapid transit to the airport is going to be via a bus connection to an upgraded Puhinui Station, and eventually a full busway. But even if it was built as heavy rail, and you didn’t have all the other issues associated with it, how long would it take? From Puhinui it’s around 6.7km to the airport and I’ve assumed a stop at the Airport business district. This results in a travel time of 8 minutes. When combined with the travel time to Puhinui it means a total time of around 41 minutes – with the bus option there’ll be a short transfer time too.
In other words, when you actually plug all the numbers in, travel times are about the same regardless of mode. One of the reasons for that is while heavy rail can travel faster and has fewer stops, it also has to travel a longer. For example, it’s almost 30km from Britomart to the airport via Puhinui compared with just 22km for the proposed light rail route.
How should you get to the airport in the future
One of the most fascinating outcomes for me from this is that there’s no clear winner. Even though light rail isn’t really about serving air travellers, from the centre of the city all options take about the same length of time. The fastest way to get to the airport will be to hop on whatever train, light or heavy, is closest to you. If you do catch a heavy rail train, then a simple transfer at Puhinui to a high-quality bus will reliably whisk you the remainder of your journey. I think this is quite a good outcome, after all we’re trying to build a PT network that is useful to a lot of people, not just one that provides an express service to one location.
Longer term, there may be a couple of other options that people could use. In particular, future regional services might only stop at one or two stations within the Auckland Network and Puhinui is likely to be one of them given it will provide for connections to the airport. That could also be used to provide a faster, but likely more expensive, service to/from the city via Puhinui.
The next step is to apply this model to other parts of the proposed Rapid Transit Network. What do you make of the travel times?