Welcome to the final puzzle for 2013. Consider this four-way intersection with a set of traffic lights. The speed limit on all roads shown is 80km/h (or 50 mph).
You are travelling at the speed limit and you reach the point before the intersection where when the lights turn orange, you are uncertain about whether you will make it across before the lights go red. The longer you take to make up your mind, the less time you have to take action. Especially when you realise you should be braking. The town I grew up in, raised the stakes by putting in a combination of red-light cameras and speed cameras.
I think that such intersections can be improved. So this month’s puzzle is: how could we improve the the intersection so that it’s easier to decide whether you should stop or continue at speed?