If we want to increase escalator capacity, why don’t we just run them faster? Well, here’s why.
On long escalators, the vast majority of people don’t want to walk. Thus, huge queues build up at the bottom of the escalator as large numbers of people try to squeeze onto the right-hand side, so that they can stand in line as they chug slowly upwards at max capacity.
There is a potential solution – one that’s likely been suggested by logistics all over the world every time they’ve found themselves in such mildly antagonising and incremental-delay-incurring situations: run things faster.
Theoretically, of course, this is possible. Escalator speeds vary a great deal anyway, even within London – those in shopping centres or department stores tend to run at about 0.5m per second, while the London Underground standard is 0.75m per second.
The escalator capacity solution
Looking further afield, city transport networks across the world run their escalators at all sorts of different speeds. New York City’s are considered slow, running at about 0.45m per second, while Prague, Stockholm, Beijing, Shanghai, and Guangzhou settle around 0.6m per second. Sydney, Singapore, and Seoul’s systems square up to London’s standard speed in the 0.75m per second region, with Seoul pushing ahead slightly at 0.78m per second. The trailblazer, though, is Hong Kong, whose escalators breeze along at 0.8m per second.
Unfortunately, a comparison isn’t that simple. London’s escalator steps are, as standard, 1m wide and 0.4m deep. Many of Hong Kong’s escalators are significantly narrower and not as deep. Whether that’s clever space-saving on Hong Kong’s part, or future-proofing by Transport for London, we may never know – but either way, it changes the rate at which steps reach the top, rendering direct comparisons based on speed alone impossible.
The escalator speed limit
What we can do instead is to look at a study carried out by four students from Hong Kong on the relationship between escalator speed in metro systems and “pace of life”. They described that metric as “the rate; speed and relative rapidity or density of experiences, meanings, perceptions, and activities”. They calculated it by combining economic, climate, employment, and population indices.
One of the things they did as part of that study is to conduct reasonably lengthy interviews with users of metro systems (principally the Hong Kong MTR) about their experiences of the escalators on that system, and how that related to their impression of the city’s “pace of life”. One businesswoman in her mid-twenties interviews for the study said that “Hong Kong people are used to the fast”; but most of the non-locals that they spoke to, mostly from mainland China, said that the escalators on the Hong Kong MTR were “too fast”.
Such comments highlight one of the biggest problems with running escalators faster. A study by Paul Davis and Goutam Dutta has already shown that the presence of non-commuters decreases capacity on London’s escalators. Meanwhile, an experiment with variable-speed escalators in New York ended up with an Indian visitor falling over.
There is quite obviously a danger to be taken into account if you’re going to start running escalators at 0.8m per second or faster. The queues at the bottom might be shorter most of the time if said escalators are whizzing passengers upwards at speed – but they’ll likely be longer while the paramedics try and reach the elderly man who’s tumbled 15m down an up escalator.
For those less interested in actual human health and welfare, and more interested in the technical side of running large transport networks, there’s another problem with running such escalators at speed. The average walking speed is around 1.3m per second. If you take the running speed of London Underground escalators – 0.75m per second – and the rate at which people generally ascend the steps if they’re walking – around 0.7m per second – you end with a speed of 1.45m per second.
So people walking up escalators are actually travelling slightly faster than they do the rest of the time. And that’s a problem. When it’s only an incremental difference (0.15m per second), it leads to nothing more dangerous than the awkward super-walk that people do for the first few seconds after walking off the end of an escalator.
But when there’s a bigger difference in speed, it can cause major problems. Either, people trip over their own feet trying how to remember how to walk on non-moving ground, and cause a capacity-reducing pile-up in the process; or people stop at the top of the escalator to prepare themselves for walking on non-moving ground. And cause a capacity-reducing pile-up in the process.
Essentially, speeding up escalators causes more problems than it solves.
Starting again
Fortunately, researchers Davis and Dutta do come up with some more sensible alternatives. Unfortunately, these are the sort of drastic changes that are much easier to implement if you haven’t built your metro system yet than they are if you’re trying to unclog a jam-packed 150-year-old system.
Of the many London Underground escalators they studied, the researchers found that those with the highest peak-time capacity were escalators with open, orderly approaches, not impeded by awkward corners and cross-flow confusions.
They found that having a corridor between the platform and the escalators acts as a filter for passengers alighting a train, improving capacity as passengers naturally filter out into two lines – one for walking and one for standing – in an orderly way (rather than the human crush you get when you come straight off the platform, turn a corner, and suddenly there’s an escalator).
Interestingly, single escalators have a higher capacity than double escalators, because passengers don’t dither trying to work out which escalator to take.
Enjoyed this!
The conclusion (that we should build stations with filtering corridors to enable passengers to self sort into fast and slow is good. But the implication is that we have the standing side wrong, as mostly in London we walk on the left and overtake slower people on the right hand side. If the standing side was on the right, that would flow more smoothly, without the last minute crossover. Alternatively we could switch to keep right in non-educational areas, but it’s very unintuitive to people who drive on the left.
Somewhere I remember one that slowed down at the ends for loading. The principle was that the treads were rotated and thus elongated along a diagonal platform. Not worth it for building floors which is most of the market but on some of the longer TfL runs could yield savings against the maintenance complications. Wonder if anyone has experienced the type.
Accelerating escalator – could not find it as search term is unclear. Must have seen or ridden on it in Tokyo.
Apparently the issue was that the rotating gear was carried with each tread so there was a cost and weight penalty.
This is the US Patent application by a Japanese designer for an improved version:
Acceleration and deceleration device and acceleration and deceleration escalator including the same
Abstract
An acceleration and deceleration device includes: a chain 19 that is endlessly guided along a predetermined first track; a U-shaped member 40 of which a terminal end portion is attached to the chain 19 so as to be swingable and a part from an intermediate portion to a front end portion is formed as two parallel members and which has a long and narrow U-shaped groove between the parallel members; and a subject moving body 102 that has a driving shaft sliding inside the U-shaped groove of the U-shaped member 40, wherein the driving shaft of the subject moving body 102 is rotatable with respect to the U-shaped member 40 within a predetermined range in the U-shaped groove of the U-shaped member 40 and the driving shaft of the subject moving body is slidable with respect to the U-shaped member in the U-shaped groove of the U-shaped member 40.
Classifications B66B21/12 Moving walkways of variable speed type
US20130220767A1 United States
https://patents.google.com/patent/US20130220767A1/en
Looks like ‘geometry’ making it steeper in the middle, wonder what H&S would make of that for walkers on the left.
@Aleks
Some N American subway systems had escalators that slowed down when they sensed no passengers, to save energy. Is that what you mean by accelerating?
In any case this type was a maintenance nightmare, not being very reliable, & didn’t save that much energy, so were replaced.
@LBM No. These are about higher throughput by faster transit but with entry/exits at regular perceived speed which was the objective of this capacity piece. It works by elongating the end steps. My Tokyo one was in 1992, and the improvement patent was 2010. Since there are no feature pieces on the web suppose the technology was not adopted.
Energy saving on LT was tried as ‘speedray’ with the experience you stated, the extra complexity outweighed the extra wear and power used. Instead where possible they manually shutdown duplicate operations or exit escalators where there was a longer interval between services. Today with technology and power costs they have returned.
TfL’s 2019 statement In line with Transport for London’s (TfL) Energy Strategy, London Underground is working to implement station energy plans that identify ways to reduce energy consumption.
Where we have more than two escalators and operations allow, station staff currently switch off the additional escalator(s) during quiet periods.
TfL will shortly launch a trial where local station teams will extend the escalator resting time at suitable locations, to reduce energy consumption further. Posters by resting escalators will explain to customers that TfL is taking this measure to reduce its carbon footprint.
In addition, as part of TfL’s escalator renewal programme, more efficient motors are being installed across the network. TfL’s newest escalators can also be placed into Economy Mode, which automatically slows them down when they are not being used.
All the escalators in the core Elizabeth line stations are energy saving and will slow down if not in use.
Other sightings reported:
up from the Bakerloo link at Paddington
Barbican end of Farringdon
Northern line up to Piccadilly line level at Kings Cross
South Kensington
They are now commonplace in Europe. Activated by pressure plate, laser beam, or radar. They run slow otherwise passengers consider them defective. Saves on power and wear. If you approach the wrong end of the machine it will start up in half speed to prevent use. If the correct end is used the machine ramps up to full speed. If no more users are detected after a time delay it will return to half speed then further time out to stop.
Regarding capacity TfL had the idea to double loads on exit escalators to clear platform congestion (at London Bridge I believe), fewer people walk up rather than down. They used staff with megaphones but it just caused confusion. My idea would be to replace the anti-slide bumpers that read Stand on the Right with LED displays, Run an education publicity campaign and flash stand both sides during Rush Hours.
Other problem, certainly in London – the step ( Riser” ) height – which I have long considered too large.
This is horribly apparent when one has to walk either up or down a stalled escalator, but is quite noticeable, even so, when walking up, or down a moving one..
But ….
If one were to reduce the riser height, to get round this, you would then be compelled to reduce the tread-width as well, which I don’t think would be a good idea.
Which means re-designing & replacing the whole escalator sets & the tunnels
I think we are now stuck with an unsatisfactory “solution”
[Snip. LBM]