North America

The Mezzanine  

What if, instead of building subway mezzanines underground, we put them at surface level, creating the space to do so by preventing automobiles from passing directly above each subway station?

La Rambla, in Barcelona

  • Eliminating underground mezzanines may become more viable as passengers pay for their subway tickets digitally rather than via fare booths or turnstiles
  • If each car-free street-level mezzanine was, say, 100-200 metres long, it would free up space for bus stops, bikes, wheelchairs, and pedestrians, making it easier to get to and from the subway
  • Putting the mezzanine at street level would allow the underground portion of subway stations to be made much smaller, reducing the cost of station construction
  • A street-level mezzanine could have a social and aesthetic value. By making the space above a subway station free of cars, it could become a nice place to wait for anyone you are planning to meet up with at the station
  • There would also be much more space available for stairwells, escalators, and elevators, making it easier to get in and out of stations quickly and comfortably and reducing platform crowding at busy stations. For deep underground stations especially, this would allow passengers to reach subway platforms from street level without having to fight through busy underground crowds to get from one set of escalators, elevators, or staircases to another
  • For subway stations that have central platforms rather than side platforms, the ability to put station entrances in the middle of a car-free street might allow the subway platforms to be located less deep underground than they would otherwise need to be. It would also allow the platform to be accessible via a single elevator shaft, rather than force passengers with wheelchairs or baby-strollers to ride one elevator to reach the mezzanine and then a second elevator to reach the subway platform
  • In certain cases, by making it easier to access central platforms, and by freeing up space for station entrances and exits generally, street-level mezzanines might allow for the Spanish Solution, to speed up and simplify passenger boarding and alighting
  • Maglev elevators? Having more room for elevator shafts, and also having the ability to access central subway platforms from surface level via one rather than two separate elevator rides, would be especially significant if technological advancements make elevators more efficient. In theory, elevators could be far more space-efficient than escalators, since they travel vertically whereas subway escalators tend to be angled at only around 30 degrees, which is actually quite a bit more horizontal than vertical. In practice, though, elevators are inefficient, since they tend to have only one elevator per shaft, leaving the majority of each shaft empty. If a technological solution can be found to this problem, then a car-free street-level mezzanine with elevators taking passengers directly from surface level to the subway platform could be a great thing
  • Staircase Diversity. The Mezzanine would leave more room for stairwells, which could allow each station to usefully have a number of different types of staircases. The staircases could differ in terms of steepness; steeper staircases are more space-efficient than less steep ones, but are also less easy to use going downstairs, less easy for seniors to use, etc. With more stairwells, some of the staircases could perhaps even be spiral staircases, which could be extremely space-efficient, but not attractive for anyone to use except when the normal staircases are overcrowded during rush hour. Some staircases could be bicycle-friendly

We probably shouldn’t need excuses to limit cars’ space or speed in urban areas, but all the same, a subway station could be an excellent excuse for doing so. Better yet, why not make the street above the entire subway line car-free? That way it would become even easier to get to and from stations, and the area around the entire subway line could become much nicer to spend time in, or to walk or roll through. I’m looking at you, Yonge Street.

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4 thoughts on “The Mezzanine  

  1. With respect (and sorry to criticise two suggestions in a row), this seems a backward idea, given that the trend is for stations (even at grade stations) to more and more be underground.

    A few points:
    – you couldn’t use the space for bus stops, etc, for safety reasons. The point of having this space it to have it crowded with pedestrians milling about, and putting buses and the like into that space would be counterproductive!

    – putting the station at grade would vastly increase the cost, not reduce it, for the same reason that we build undergrounds at all: it is much, much more expensive to buy land than it is to dig a tunnel. Now, you can say that you’d build your stations just in the middle of the road. But for one thing, stations are huge things, not thing you can just plop in the middle of the street – just look at the footprint of a modern station like the upgraded tottenham court road, compared to the size of any nearby road. And for another, the road isn’t just there randomly. It’s there because people use it to drive down, and closing down a major road has huge knock-on effects.

    – you’d also cut out your revenue stream. With underground stations, you subsidise your costs by renting the space you create out to shops and restaurants and the like, but with a station in the middle of the road, the shops and restaurants are there already and don’t have to pay you rent!

    – it’s less efficient in terms of transporting people underground. As it is, the idea is to get everyone part of the way, and then people can spread out to go where they need to go. If you’ve got, say, three different lines, in two directions, all accessed directly from the surface, then you’re packing people less efficiently and you’re wasting money and electricity.

    – there is no conceivable reason why you’d need maglev lifts! Their top speed may be hundreds of miles an hour, but since you’re only going a few hundred feet at most, and often less than that, that top speed is irrelevant! It would be like owning a special Ferrari just to take you from your front door to the street…

    – elevators are not more space-efficient than escalators, because in this context the ‘space’ you save is space you’re not doing anything with anyway. Both methods connect a small footprint at the top to a small footprint at the bottom, and the fact that the connection between the two may be diagonal is irrelevant, unless you actually need to, I don’t know, herd giraffes beneath the escalator, since that space between the floors isn’t being used for anything else anyway (you don’t even need to excavate it in some cases). And of course, the actual horizontal footprint of escalators on each floor is much smaller than that of a lift.

    – why are you planning for ‘staircases’ at all? This isn’t the 19th century! We have electricity now! Staircases are just a hazard and an obstacle for the disable. [that said, spiral staircases are not unusual in tube stations, but they’re almost entirely for emergency purposes].

    – are you talking about staircases to the platform? Then you haven’t gained any space at all for them, because the concourse can be whatever size you need, so long as it’s underground. It’s only if you put it on the surface that it’s size-restricted.

    – important to underline: you can’t just put a concourse down a street and expect it to be meaningfully connected to platforms below because the platforms will almost certainly not follow the route of the street!

    – yes, eventually, more and more shopping streets will be pedestrianised. But inner city roads don’t exist for fun, and they’re not congested because everyone is lost: they’re there because they’re essential to the maintenance of the city and its population. You can’t just randomly shut down every road that happens to be near the route of an underground line! Civilisation would, and for once this sentence is not an exaggeration, collapse!

    • Hey, no worries, I really appreciate the feedback, positive or negative. Thanks very much.

      My line of thinking was that surface road space is being under-utilized because modern cars are so inefficient, compared to walking/biking/micro-cars/etc., whereas underground space is extremely expensive. So maybe you could improve a street’s throughput by limiting cars, so much so that you could still have some space left over to put in extra subway station entrances?

      Regarding the half-baked maglev elevator idea, my reasoning was that maglev elevators could (in theory) be efficient not because of their speed but because of their ability to circulate, which allows for many elevators per shaft. Basically you get the benefits of a circulating paternoster elevator, but without any of a paternoster’s speed/safety drawbacks. In other words, a maglev elevator could in effect be a vertical escalator, rather than the not-even-diagonal 30 degree angle of a conventional escalator. I take your point about giraffes, but I’m still not sure I agree.. humans are pretty tall too, and in many cases escalators take up a decent amount of space on subway platforms themselves. Couldn’t it be possible, hypothetically, for a maglev elevator to have a far smaller footprint per passenger than an escalator?

      • On roads: I’m not sure walking is more space-efficient than driving – you have to bear in mind not just packing density (walking is great!) but also travel time (walking is not great! particularly on packed roads! I’ve tried walking down Oxford Street on a busy day and I’m not sure I buy it as a model we should be based future transport on!). I’ll accept for the sake of argument that cycling is more efficient than driving. But we also have to bear in mind that many, perhaps most, driving journeys can’t be completed on bikes – this includes almost all commercial freight, plus journeys by/with the old, disabled, or young, plus long-distance journeys, plus journeys where you have to take something with you.
        Indeed, from my experiences in London, I don’t think I ever knew anyone who regularly used cars for ordinary travel, only for things for which cycling and (the extensive) public transport weren’t an option. And yet the place is STILL logjammed! Most of the removable traffic has already been removed…

        Anyway, I don’t have a problem with carefully-selected streets being pedestrianised. I just don’t think that taking pedestrianised streets away and turning them into railway stations is a cost-effective use of space… after all, underground space is expensive, but it’s still much cheaper than surface space!
        (and yes, some underground stations could do with an extra entrace here and there – but by and large it’s not a big issue, as large stations already have half a dozen or more each. )

        On lifts: OK, that’s an interesting direction. I’m unconvinced, though. I assume you mean that with magnets you can make you lift rise up one shaft, but then descend a second shaft, allowing you to have a second lift rising up the first shaft at the same time that the first is descending in the other shaft?
        The problem here is that because the lifts from surface to concourse will have such short shafts anyway, you won’t be able to squeeze many more lifts in. Sure, you could have two lifts… but if you need two shafts to do that, then it’s not an improvement. How many more lifts do you think you could put into one shaft that’s only tens of metres in total length? Bearing in mind that you need these lifts to be accelerating, braking, and stopping. If you’re in the second lift in the shaft, and the top lift stays at the top for longer because someone presses the ‘keep doors open, an old woman is stuck’ button… what happens to you? First, it means your lift has to suddenly break in less time/distance than it would ordinarily do. And second, it means your lift has to just stop in the middle of the shaft for a while… which a lot of people wouldn’t be comfortable with! (come to think of it, the idea that you could just trap one lift in the shaft perpetually by leaving a wedge in the doo of the top lift is probably something of a health and safety issue…)

        I’d also point to what happens in reality. In reality, building a circulating lift isn’t that hard: it could be a self-ascender, or a hydraulic or pneumatic system, or a roped system with a ‘catch and release’ device at the bottom. But these have never taken off precisely because they’re not worth it.

        Krupp build electromagnetic lifts (I’m not sure if they’re genuinely maglev, though), but they’ve only come into use in very tall buildings – the taller the shaft, the bigger the benefit of being able to have multiple lifts in the shaft, and the more floors to stop at, so the smaller the problems of one lift blocking the way for others. It wouldn’t make sense for a short, one-stop lift, I don’t think. Krupp do advertise their system for underground stations – but the idea there isn’t circulation per se, but effectively using it as a small, horizontal train that just happens to also be able to go up and down floors. This probably will become a feature of the largest interchanges, particularly where it can be integrated into the surrounding or surmounting buildings, but it will require stations that are built from scratch specifically to accomodate it, and it probably won’t ever make sense for most small stations (where there aren’t lots of platforms to choose from and a skyscraper on top).

      • Good points. I think the idea is that the lifts could be sort-of 3D: they can move right/left, forward/back, and up/down. So for e.g. if you had four chutes arranged in a square (2 going up, 2 going down), then you could manage the “keep doors open, an old woman is stuck’ problem by having the next lift arriving pivot in the other direction instead.

        Of course, perhaps there wouldn’t be enough space for a square of four chutes to be put in a subway station… In general, though, even four elevator chutes would take up much less space than elevators, and might also be quicker to use considering that they travel so much more vertically than elevators do.

        I don’t know how many more lifts you would be able to put in per shaft – you’re right of course that that is a key question. But if each lift travels fairly slowly – say, at the same speed as an elevaotr – then maybe you could bunch them pretty close together, without losing on safety or comfort?

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