D is For Door - Obviously

I was on a train in Kent on Monday, confronted by a pair of buttons marked D and L. They were beside the toilet door, and I wanted to close it.

Now, I'm reasonably familiar with doors. I've been opening and closing them for over seventy years, generally without requiring written instructions. I was therefore looking for something marked O for Open and C for Close. Not an unreasonable expectation, I thought.

But no. The buttons were marked D and L.

D? What the hell does D mean?

Fortunately, the railway had anticipated my intellectual shortcomings and provided a substantial notice explaining how to operate a door. Apparently, you press D to close it, L when flashing to lock it, and D again to unlock and open it.

D, it eventually dawned on me, stands for Door. Of course it does. Silly me.

The same button opens and closes the door, depending on what the door happens to be doing at the time. L locks it, but only when it flashes. And D also unlocks it, despite there being a perfectly serviceable L button sitting alongside it.

This is what happens when engineers design things for people who already know how they work.

Somewhere along the line, somebody decided that labelling a button according to the object it controls was more sensible than labelling it according to what the person pressing it actually wants to do. And when that proved insufficiently obvious, somebody else designed a notice explaining the first somebody's design.

There is a whole discipline devoted to this sort of thing, called human factors engineering. Its central proposition is that machinery should accommodate human behaviour rather than require humans to learn the peculiarities of machinery. The railway appears to have approached the problem from the opposite direction.

And it's not as though this is some complicated piece of equipment. It's a bloody toilet door.

The extraordinary thing is that the solution is so simple. If you want someone to open a door, give them a button marked OPEN. If you want them to close it, give them one marked CLOSE. If you want them to lock it, LOCK would seem an inspired choice. Three buttons, three functions, no explanatory essay required.

Instead, we have two buttons, a flashing light and an instruction panel that wouldn't look entirely out of place beside the controls of a nuclear submarine.

I managed to operate it eventually, although I did wonder how someone elderly, visually impaired or simply desperate for a pee might fare. Particularly if they were unfamiliar with the system and the train was bouncing around the Kent countryside.

The really irritating thing is that the designers probably regard this as an elegant solution. They've reduced the number of buttons from three to two. An efficiency saving of 33%, no less. All it cost was the ability of an ordinary passenger to understand the bloody thing.

And that, I suspect, is the problem with an awful lot of modern design. We have become remarkably good at making things clever and remarkably bad at making them obvious.

A door should not require a learning curve. Especially when you're on the wrong side of it with your trousers down.