Fluid dynamics of the London Underground

As many of you will know, I work in London even though I live outside the capital. This entails me not only having to commute into London, but also having to navigate the London Underground in order to get to work (this is largely behind why I can post book reviews so regularly – a long commute gives me a lot of time to read).

In particular, I travel on the Victoria line, getting on at London Victoria station. If, or when, my mainline train is late in, then the station is extremely busy and the Underground station is shut. This prompts this kind of view in the morning:


When you get people all trying to get through the station, I have observed a certain sort of “fluid” behaviour of people, where the crowds move like a gas or a liquid. One aspect I find quite fascinating is the ability of regular commuters, like myself, to walk across a busy concourse without bumping either into one another or into the ambling tourists, particularly when walking at right angles to one another. I attribute my ability to dodge oncoming traffic to my years of training on video games, in particular the Indianapolis 500 and Nascar racing games.

Those going to the Victoria line will be familiar with the recorded instructions to “stand on the right and walk down on the left.” Anyone who travels through London ought to be familiar with this maxim, though having escorted my mum from St Pancras to Kew Gardens and back again, I’m aware that it’s not a truth that is universally acknowledged.

However, in the mornings there is only one downward escalator, which creates something of a bottleneck. Very frequently, both the left and the right side of the escalator are crammed full of people standing. No one on either side can walk down. Yet when the barriers have been closed and the escalator cleared, then the adherence to the rule as soon as the barriers have been reopened is very strong. So how do we get from the situation where those on the left can walk down to the one where they are forced to stand?

Well, I have observed how a blockage begins on the left hand side. What happens is that someone is standing on the right when they get impatient at all the people walking past them, so they decide that they want to change lanes. However, in order to do this, they need to break the smooth flow of people. i.e. someone on the left has to stop in order to let the lane-changer get in front of them. Because one person stops, the person behind them also has to stop in order to not walk into the back of them. Before long, the blockage point has spread all the way to the top of the escalator.

So when the mainline train is late into Victoria and I’m having to rush to make it to work on time, if you dare try to cross from the right to the left, don’t expect me to give way to you. What you do will hold other people up and cause a general nuisance.

There is another feature of Victoria which I have yet to make up my mind about. Those of you familiar with Victoria underground station will be familiar with the ‘bag lady in green’. Never having a ticket, she will venture through towards the barriers before turning back and walking into the oncoming crowd. It seems as though this is her version of being sociable. She’s always friendly and willing to say hello, though I do wonder how long she spends at the station each day and what her life is like at other times. I might well think something similar about the thousands of other travellers on the tube with me, yet the well-being of this one person concerns me slightly more. I wonder at her motivation for her peculiar behaviour, though I dread the day when I realise she might not be there any more.

One response to “Fluid dynamics of the London Underground

  1. Now this is really interesting, as it seems to be a very special kind of fluid dynamics to me. In actual fluids, the atoms or molecules are going randomly in all directions on the local scale, which is not the case here. I wonder whether anyone has studied this in earnest. The London Underground would be the perfect laboratory.