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Twice this last week, I noticed people signalling right-turn as they entered a roundabout that I also was approaching. Then they didn’t turn right but rather went straight through the roundabout (following the lane, of course).

That is one of the things that bugs me. Apparently some people are being taught to signal right when you’re entering a roundabout, and then signal again when you’re exiting a roundabout.

I don’t mind the signalling when exiting a roundabout, but it’s the “signal right when entering a roundabout” that’s the problem. These people are considering the road meeting the roundabout as an intersection. I consider the whole roundabout the intersection.

Here’s how I see it.

First up, a generic intersection :

This one doesn’t have any controls, so it’s at a high risk of people crashing. We need some way to coordinate who has the right of way. So we could make it a 4-way stop :

That’s better. Now if you were approaching this intersection and wanted to turn left, you would signal left and you approach it, and the car would cancel the signal after the turn was completed.

Everyone agree? Ok, now we’re going to change the traffic control method from stop signs to a traffic light :

Does that change anything if you want to turn left? I hope not. You would activate your left turn signal as you approached the intersection, and the car would cancel the signal after the turn was completed.

In each case, the control method inside the dashed box doesn’t matter. You have options for the intersection, so you signal as you approach the box to let people know which leg of the intersection you’ll be taking.

Now let’s replace the stop light with a roundabout :

I’m stating that it doesn’t change anything – you should signal left and you approach the intersection, and the car would cancel the signal after the turn was completed.

The problem with signalling right to enter the intersection is that people on the other legs of roundabout can’t tell the difference between that and signalling to take the first roundabout exit. It’s a bad idea.

It doesn’t add any information to the situation. The reason for signalling at intersections is to add information to the situation so that other drivers can make better decisions.

When entering a roundabout, everyone has to do the same thing – a slight right curve. Turn signals are to inform other people that you’re going to deviate from the current path, or to let them know which option you’re choosing when there are multiple options. When entering a roundabout, there are no multiple options (that’s one of the benefits of roundabouts) and you’re not deviating from a path. The path deviation should come when you exit, not enter a roundabout.

So the turn signal doesn’t add any information that’s needed. But it’s worse than that – it adds bad information. It causes confusion and delay, and that’s the worst thing that could happen, both here and on Sodor.

One caveat is that this is for roundabouts, not traffic circles. And it seems to me that whoever is teaching the signal right whenever entering a roundabout is someone who grew up with a traffic circle. Because those aren’t one intersection – they are big and are individual intersections around a circle.

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