I recently finished reading “The Design of Everyday Things” – a classic book that gets you thinking about everyday “user interface” around you – doors, gadgets, machines, bathroom taps, etc. The principles in the book apply equally well to software UI, game design, and I’d argue programmers designing APIs for one another. I recommend it highly.

I was particularly amused to see the HST train doors featured in there – something most British train users are painfully aware of, but have somehow actually gotten used to, to the point that we take them for granted and have actually forgotten just how laughably bad they are. In case you don’t know what I’m talking about, here’s how you get out of the train:

That’s right – open the window, lean out and open the outside handle. Try not to lose your balance and fall onto the platform! Notice how a real person’s arm doesn’t reach the handle quite as easily as the stick figure in the diagram 🙂

Don Norman didn’t actually get to the bottom of the issue:

Clearly difficult to use, but why? I haven’t the foggiest idea. To prevent accidental opening? To make it so that young children cannot open the door? None of the hypotheses I have tried stand up under close examination. I leave this to the reader.

My childhood recollection is slightly hazy, and I can’t find a definitive source to back this up, but I seem to remember they reached this state of affairs in 2 steps: they firstly removed the interior door handles as a dirt-cheap “safety” measure to discourage people from getting out of the train before it stopped, then realised that they h adn’t actually discouraged everyone and had instead made jumping early even more dangerous, so they added a central locking system to keep the doors locked until the train stopped. Of course, in a quintessential piece of British train-related incompetence, they didn’t bother to put the handles back on once they had central locking.

Was that to “save money” again, perhaps? It’s funny how they spent more money overall than just adding central locking, and ended up with a solution that’s so much worse than central locking alone. They did, at least, provide a mysterious puzzle for foreign visitors, and some good material for Don Norman’s book 🙂

But wait! There’s more!

My regular train to work exhibits another piece of poor door design, not as extravagantly bad but nicely illustrative of a fundamental UI design principle. Here’s the internal door between train carriages: how do you think the opening mechanism works?

Press that button in the middle, right?

Wrong!

At some point you’ll notice someone struggling with one of these doors not working, pressing the button harder and harder in growing frustration, and you get to show them what’s really going on:

That’s right, the door is actually operated by a motion sensor that has a very narrow range of detection, aimed at the area round that button. If the door’s not opening for you, the thing to try is reaching up and waving your hand right in front of the sensor!

This is a brilliant illustration of a problem Don Norman talks about early on, about conceptual models. His words couldn’t explain it much better:

The design model is the designer’s conceptual model. The user’s model is the mental model developed through interaction with the system. The system image results from the physical structure that has been built (including documentation, instructions and labels). The designer expects the user’s model to be identical to the design model. But the designer doesn’t talk directly with the user – all communication takes place through the system image. If the system image does not make the design model clear and consistent, then the user will end up with the wrong mental model.

The design model here is that the door is motion-sensor-activated. But the system image communicates to the user that it’s button-operated, so the user ends up with the wrong user model. Worst of all, the designer of this door went to lengths to create this bad system image. They deliberately designed a piece of plastic that looks like a button, aimed the motion sensor at it, and even added a light inside the button to highlight it more prominently to the user. They should have read Don Norman.

But then, there is something quaintly amusing and almost endearingly British about incompetence at running trains 🙂