The City Rail Link is a crucial piece of infrastructure for Auckland but it’s not a magic bullet and doesn’t have unlimited capacity.
We’ve been seeing a lot of comments recently, both on the blog and elsewhere, questioning why the City Rail Link (CRL) isn’t being used more, why we’ve suggested a second, complementary network of light rail for some routes. I’ve even seen it suggested that we don’t understand what the CRL is or how important it is strategically – which is frankly hilarious given we’ve written around 500 posts explaining almost every aspect of it.
I suspect that what some people don’t realise is just how much impact the CRL will have.
- It adds two new stations to the city centre, making the rail network more convenient to a lot more people and therefore significantly growing demand. This includes Aotea, which by virtue of being the closest to the largest and most dense employment, education, entertainment and housing areas in the city, plus by not having half of it’s catchment be water, is expected to become the busiest in the city.
- In addition to having stations closer to where people want to be, the CRL significantly shortens journey times for those on the western line by cutting out the detour via Newmarket. This will further drive demand from the west.
- The Unitary Plan that has been adopted will see a lot more people living near close to the rail line, expanding the pool of potential users. One big and likely developments will on the land above the CRL tunnels at Mt Eden
The point of covering these benefits is to remind people that the CRL is going to make the rail network extremely popular and demand to use it will skyrocket. To meet that demand we’re obviously going to have to run more trains to meet that demand. But just how many extra trains can we run?
Our current network runs up to 20 trains per hour (TPH). This is made up of 6TPH on the Western, Southern and Eastern lines and there are 2TPH on the Onehunga Line. Based on our current setup (and assuming we had enough trains), we could transport a maximum of 14,250 people an hour.
According to Auckland Transport, upon opening the CRL will be able to handle 18TPH per direction through the tunnel, or 36TPH in total. That’s up to an extra 12,000 people that can be moved to the city, almost double what could be done today. Both Auckland Transport’s plans and our new Congestion Free Network suggest that services should be through-routed, with the Western and Onehunga lines joined together and the Southern and Eastern lines also joined. Doing this allows us to run an extra 6TPH per direction through the CRL. This could be used to boost the frequency of each line at 9TPH or as AT currently plan, to use this to run additional peak services on the Western and Eastern lines that run through the CRL then terminate. This doesn’t leave any room for additional routes.
AT have also confirmed that with additional investment, the capacity of the CRL could be further increased to 24TPH per direction, or 48TPH in total. AT say one of the investments needed will be to signalling as we will need automatic train operation. All of this would allow for each of the two lines to be running at 12TPH for five minute frequencies across the network. This would allow for almost another 10,000 people per hour to be moved free of congestion for a total of up to 36,000.
The point of all this is that we’re going to need all the capacity the CRL can deliver just to serve the existing rail network in the future. The CRL opens up a huge amount of capacity for our transport network but that capacity isn’t unlimited and there is also isn’t the capacity for it to be used for a whole network of other lines.
This was also one of the factors as to why we’ve chosen to use light rail to provide some of the new rail lines in our Congestion Free Network 2. With the CRL maxed out in serving the existing rail network, any additional heavy rail routes would require the entire route to be constructed from scratch. While that’s technically possible, our geography and topography means it would be unlikely to be affordable, even if we had a very favourable government.
Of course, building our Congestion Free Network doesn’t mean we couldn’t still build new rail routes in the future and given the amount of capacity CFN has, when we get to the point of needing further investment we’ll know we’re doing well.