Information is power when crossing the road

By Brian Clegg

We are all aware how important information is, and anyone who has designed a system or computer program also knows that feedback is an essential type of information in making things go well. Our entire physical interaction with the world is dependent on feedback to show whether or not we need to change a course of action, or how something is progressing.

This is why a mechanism that tells you how far you are through a process (a progress bar or a percentage complete value) is much more effective that simply indicating that a process is underway, even if the percentage isn’t particularly accurate. A Windows-style ‘floaty dots to show you something is happening’ only indicates that a process has started. It’s a touch of feedback, but it gives no indication that things are continuing to happen – and that’s bad. Feedback should continue to be updated until the process is complete. That way, we feel in control, even if we can’t actually do anything. It’s a major weight off the mind.

Which leads us on to crossing the road. Traditionally in the UK, crossings linked to traffic lights have had a red/green person on the opposite side of the road. When it’s green you can go, when it’s red you shouldn’t. It’s a crude form of feedback, but it’s a start. And crucially, because the sign is on the opposite side of the road, the feedback continues throughout the crossing process. If the lights start changing when you are half way across, you know about it. More recently, though we’ve seen a divergence, replacing the old indicators with two alternatives. One is a huge step forward, but the other (which is far more common) is disastrous in terms of feedback.

The step forward I’ve only ever seen in London, and it’s brilliant. A fair number of London crossings have a countdown to the lights changing. So not only do you have the red/green person, you know how many seconds you have left to cross safely. This is superb. As you cross, you have constantly updated feedback, always accessible. This is how it should be done.

Unfortunately for those oiks amongst us who choose not to live in the metropolis, there’s a problem. Our crossing indicators are being increasingly replaced by ones like the image above. Here we still have the red/green person – but the information is provided on the side of the road you start from. This is fine in terms of getting started. But if you begin to cross when the green person was already showing, you have no idea how long the indicator has been green. If the lights start changing when you are part way across, you can’t see the green man change to red. There is no way to see the status when you are at your most vulnerable, in the middle of the road. You can’t even see the indicator for people from the other side, as they are angled away from the street. So you have to cross entirely without feedback. And that is stupid indeed.

Please talk to some decent interface design people, town planners.

Now Appearing is the blog of science writer Brian Clegg (www.brianclegg.net), author of Inflight Science, Before the Big Bang and The God Effect.