Comment by decimalenough
7 days ago
Small trains and small stations are good until they aren't, and then you're screwed.
Singapore built the orbital Circle MRT line exactly as the author wants: small trains (3 carriages, vs 6-8 on other line), small stations to fit these trains, frequent fully automated operation.
However, the line turned out to be much more popular than planners anticipated, with the result that at rush hour, it's common to have to queue just to enter the platform where you need to wait for multiple trains to arrive before you can squeeze in.
And the tricky bit is that there is essentially nothing you can do now to fix it. There's a hard physical limit (around 90 secs) on how fast the cycle of a train arriving, people getting on and off, and departing can get, and retrofitting all 30+ deep underground stations to be larger would be an insanely expensive and disruptive exercise.
That's true, but if you've kept a lid on construction costs as light metros tend to do, the public will embrace building new relief lines that bring more service to areas with moderate access. That adds big capacity you can then continue to grow into. Paris is a great example of this, they often just add whole new lines rather than trying to wring a bit more capacity from existing ones.
This makes a lot of sense to bring life to new districts naturally.
Look into Streetcar Suburbs for a American examples. You could do worse than starting with https://en.wikipedia.org/wiki/Streetcar_suburb
> essentially nothing you can do now to fix it
You can build another line. This one was cheap and the demand is clearly there. And two medium capacity lines are generally better than one high capacity line in terms of offering more options to travelers.
It is much more expensive to build another line at that point due to the increase in density of the city (and sometimes new requirements of stations to meet building codes). Nearly every high volume transit system out there has choke points that are extremely expensive or impossible to fix by building another line. The tunnel between VA and DC on WMATA’s Orange, Silver, and Blue lines is a 20 year project. Tracks for LIRR to go to Grand Central took 60 years from proposal to opening. It is viewed as nearly impossible to build a line parallel to the MBTA underground green line, a system that has short two car trains and 4 branches above ground on the Boston side, so very easily could use a parallel line.
Singapore started building MRTs in 1982 and essentially never stopped. However "just build another line" is a bit glib when you're dealing with a city state of 6 million people on an island roughly 40km x 20km. There is a huge opportunity cost if land is misused or underused.
Well, at least we are putting our trains either on Pylons or underground. But you are right about opportunity costs nevertheless.
Also to add: building a high capacity line (say with 2x the capacity of the Circle Line) doesn't take 2x the land. There are obvious economies of scale.
Building two lower capacity lines has some diseconomies of scale, as the opportunity costs of the land use mount.
> This one was cheap
Singapore's MRT lines are some of the most expensive public transport projects ever. The Circle Line, fully automated and fully underground, cost S$10 billion[1]. The recent Thomson-East Coast Line, still partially under construction, is projected to cost S$25 billion[2]. It was not 'cheap' by any means.
> You can build another line
Singapore is building another line: the Cross-Island Line[3]. It has planned or is constructing at least three more lines[4][5] to achieve something like 460 km by 2040, thereby exceeding the length of the London Underground. About S$100 billion is earmarked for public transport expansion.
But the Circle Line was, as someone who has used it ever since it opened in 2009, ill-conceived as a 'small line'. It is heavily overcrowded. Because of the immense traffic and somewhat lacklustre maintenance, it has suffered several delays and breakdowns. The ideal thing for LTA to do would be to expand each station's capacity, because it links all of Singapore's radial lines at heartland residential areas.
[1]: https://medium.com/from-the-red-line/was-the-circle-line-bui...
[2]: https://www.mot.gov.sg/news/Details/speech-by-minister-khaw-...
[3]: https://www.lta.gov.sg/content/ltagov/en/upcoming_projects/r...
[4]: https://www.lta.gov.sg/content/dam/ltagov/who_we_are/our_wor...
[5]: https://en.wikipedia.org/wiki/Mass_Rapid_Transit_(Singapore)...
A similar thing happened with SkyTrain's Canada Line, where it reached capacity very soon after it was built. They did plan a contingency to be able to extend the platforms for somewhat longer trains, however.
Canada Line is a bit weird since it wasn't built by Translink and doesn't use the same technology as the rest of SkyTrain. It was under built by the P3 out of caution for opening in time for the Olympics and extreme cost control, but they were really pessimistic in ridership projections. It was always going to burst at the seams pretty quickly, especially with all the transit oriented development along the route. It should have been built to the same ~80m platform as the rest of SkyTrain.
My ideal default rapid transit buildout for midsized urban areas would basically be SkyTrain with value engineering to extend the platforms to 100 or 120m with minimal cost in the future.
When I first used it, when it was first opened, I couldn't believe how tiny the platforms were. I don't think I'd seen anything so noticeably small before. It was a huge let down. It seemed that the planners/designers were completely clueless on what is required for transit line. Didn't they use the Skytrain and see how busy it was at the time? And if you are going to spend all that money building it in the first place why would you build it so small from the get go? The only explanation was they knew it was too small but they just built it so they could say that they got it done. A big fail in my books. They should be ashamed of themselves.
> and retrofitting all 30+ deep underground stations to be larger would be an insanely expensive and disruptive exercise.
But before this you had no idea that there was so much demand, right?
It's quite a lot easier to sell a huge monetary upgrade on something oversubscribed rather than a huge monetary outlay that may be a complete white elephant.
It's an order of magnitude easier and cheaper to dig out a 6-car platform the first time around than to expand from 3 to 6 when the system is already operational. And it's a one-off price too: if the platform is built but not used, it incurs essentially no operating costs to have it sit there waiting for the day it's needed.
Everything you said is completely orthogonal to my statement: "It's quite a lot easier to sell a huge monetary upgrade on something oversubscribed rather than a huge monetary outlay that may be a complete white elephant."
A better solution that no one has the political will to implement is inferior to every solution that can actually be implemented.
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But that’s not what history shows us. The subway with the second most ridership in the US is WMATA. How did they get there? By going big with their plans in the 1960s. All the systems that thought small in that era (MARTA, BART, LA Metro) have much lower ridership to this day.
There is a good basis to this. Every new mile and station you add to a system compounds on the size of the system. The 11th station connects you to 10 places. The 51st station connects you to 50 places. Build small and you never get the critical mass needed to see widespread adoption.
What is the small aspect of BART? They have ten-car platforms and all that. ETA: the Internet thinks DC Metro platforms are 100 feet shorter than BART platforms.
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The worst thing is the small line creates induced demand for that route. As in, people will literally move house and get jobs etc that are dependent on the route. So after they build it, the societal cost of "pausing for upgrades" is massive.
Why not make the train longer and have it stop in the station in sections?
probably safety issues are a factor, it would be hard to get every one off if something happened at a station. But also it probably wouldn't get you much benefit over having two trains. The main advantage would be the back half would theoretically be able to load unload a little faster then if it was a second train waiting to come into the station, but with the downside that now the front half of the train needs to wait for the back half to unload and load before it can go on it's way
The replies to this comment remind me that the supposed unavoidable law of induced demand evaporates pretty quickly amongst urbanists when talking about things they want to build. At the risk of sounding really snarky, “just one more line bro”.