A clearer network for the City Rail Link?

This post was originally published on Linked In by Nicolas Reid. It is republished here with permission.

Auckland is now just a year or so away from having the keystone of its urban rail network complete. As I wrote about here, the City Rail Link will be a literal game changer for public transport in the city buy making train trips faster and more frequent, by boosting capacity and by running trains from one side of the city to the other.

However, I wonder if the plans for how those trains will be run are actually the best they could be?

How to show the new rail network on a map?

I came across a twitter discussion on the difficulties the rapid transit map designer was having to represent the rail lines when the CRL is open. In simple terms, the current plan is to run the Western Line through the CRL tunnel and out to the Eastern Line, and vice versa, while the Southern Line will pass through the city and loop back on itself to and from Otahuhu.

The designer’s problem was how to represent the red southern line doubling back on a map. Apparently, they’re trying a few options for showing the same service pattern, which you can see in their pictures which I’ve copied below.

• two different lines of different colours (red and purple), where the colours change at Waitemata station,
• two lines of different shades of red that blend into each other across the CRL,
• a continuous red line that doubles up as two parallel lines between Newmarket and Otahuhu,
• a single line with a loop that merges back into itself at Newmarket.

There isn’t really a perfect solution here, each of these creates problems for a person looking at the map and trying to see where the lines go to and from. The option with two different lines with different colours, has a big flaw because it tells the map reader that those lines end at Waitemata station, when in fact they run through. Someone getting on the purple line wouldn’t know that their train actually takes them through to Waihorotiu and beyond. The option with blending shades of red has a similar, but less pronounced, problem.  It still presents either end of the service as a different line. The third option of the single line merging onto itself has the opposite problem, and arguably more confusing. It has no information on which end of the red line goes where. You can’t tell, for example, that the trains running out of town via Parnell only go as far as Otahuhu, while the ones running out via Grafton go all the way south.

In my opinion the lesser evil of these is the last option, showing the red line as a single service that doubles back upon itself in a double line. This at least presents the single service pattern correctly, and shows where the ends of the line actually run and how far they go. However, it’s still not great for a user at those double up stations, where you’d have the same T2 Red Line coming through each station going to four different directions or destinations. That is confusing!

So this begs the question, is this an issue to be solved with graphic design, or does the difficulty lie with the network itself?

Is a loop the best way to run the network?

Working in network design I’ve found that if a network is difficult to put down on paper, it’s also difficult to use in real life. If a designer struggles to show where the trains go on a simplified diagram, how are the users supposed to find out how to get where they want to go?

It’s my view that having the southern line train services loop back onto themselves is not the best way to run trains through the CRL. Part of the value of the CRL is having through-routed trains, rather than stopping at the terminus downtown they carry on to other stations to let you access a wider range of destinations. With the plans above you can see this with the green east-west line, for sure, but you don’t get it with the red southern line.

The problem there is that if you loop a line back onto itself, you literally running the service back through the stations where the train has just been. So, the first issue of loops is the confusion outlined above, knowing which way round the loop this version of the red line is going and whether it stops up here or down there. The second issue is that people don’t really want to travel in circles, they are by nature indirect and the opposite of the fastest way between two points. So a full loop is almost useless to getting to stations the wrong way around the circle. If you are at Newmarket and trying to get to the next station at Parnell, you’ll end up waiting for the trains that go directly there, even if half of the trains on the line go there around the full loop via Grafton, the CRL stations and downtown.

The third issue is you don’t actually get any through routing. If you come in on a train that runs through the stations from Otahuhu to Newmarket, there is literally zero benefit for passengers to continue that train back to the same stations from Newmarket to Otahuhu. It just means the same train on the same line stopping at the same stations a second time. This means that the southern line doesn’t benefit from that through routing benefit.

There are some other potential issues with the southern line loop plan, particularly around the passenger loadings and capacity. If you consider the line between Otahuhu and the city centre stations. That network means half of the red line trains will have come from Papakura and Pukekohe, stopping at twelve southern stations before Otahuhu and presumably being quite full. The other half of the trains will be starting at Otahuhu as their first station, and start completely empty.

Now in a basic transport model this will look great, the demand will be averaged across the trains and will look nice and even north of Otahuhu. But in reality, half the trains will be chockers, and half will be empty, with the real-life utilisation being lower than expected. Passengers would have to consider whether the cram onto the next train that comes along, or if they sit and wait for the next one hoping it will be free. In my experience, people default to the devil they know and will rather catch a crowded train in front of them that risk waiting for another one that may turn up later.

There is possibly a similar issue on the Eastern Line, I understand that the projected demand joining the train is expected to be high from Sylvia Park and Glen Innes, and very high at Panmure with thousands of patrons transferring off the eastern busway and Pakuranga buses. This may be a problem if the eastern line trains continue to start at Manukau and pick up at the stations from Puhinui to Otahuhu. They might already be too full when they arrive at Panmure.

There’s another way to frame that discussion. The plan is to consistently start a line at Otahuhu, with a while line’s worth of empty trains beginning their run to town there all day every day. So, wouldn’t it be better to send those empty trains straight to Sylvia Park and Panmure to pick up the big crowds with that capacity, than to send those empty trains to the comparatively less busy stations on the other line?

An alternate option

My suggestion is that Auckland tweaks the CRL network plan to remove the southern line double back loop, and instead run it to Otahuhu via the eastern stations. This effectively means swapping the Green Line to run via Parnell-Newmarket-Penrose on it’s way between Swanson and Manukau, so the Red Line can run via the eastern line after the CRL to its terminus at Otahuhu. This is shown below (this also shows the Onehunga branch as a shuttle line, which I have discussed before, but either a shuttle or the crosstown line still works).

What that means is that one end of the red line would start at Otahuhu and serve the eastern line before going through the CRL and out south to Pukekohe, and vice versa. The green line would still run a crosstown pattern, but via Parnell, Newmarket and Ellerslie, rather than via Orakei, GI and Panmure. For travelers from the west those are probably more useful destinations than the suburban east. That removes the loop and the double ups, and I expect would spread the demand better across individual trains.

This would be the same number of lines, same number of trains, same movement through the CRL and junctions, and same total capacity, but a different routing that probably works better for utilisation and loading, and it definitely results in a more legible network… and a clear and easy to read map.

So what do people think of this alternative routing, what would be the benefits or problems of running the network this way?

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