[bnralt]

> The worst roundabout beats the best 4-way stop any day of the week. Sometimes there really are easy answers.

Maybe you haven't seen the worst ones, then. For instance, one by my house had traffic lines which gave people the wrong impression about the right of way within the roundabout, leading to every vehicle treating driving like that. I actually drove like that as well for a long time - when you're spending every day driving the exact same way that the hundreds of other cars surrounding you are driving, and the lines on the road suggest that it's correct way to drive, it's easy to mistakenly think this is what you're supposed to be doing.

Then it hit me one day - this isn't how right of way works in a roundabout at all. I talked to others in the area, who were surprised when I brought it up. That's what the lines implied, that's what everyone _did_, but that's not how it was supposed to be used. Everyone was driving through this incorrectly. And it was a major roundabout, that had some of the heaviest traffic in the city.

Maybe it didn't matter because everyone was driving incorrectly, which worked most (but not all) of the time? But when it wouldn't, the accident would be a T-bone, so we can't say that roundabouts eliminate those.

Years later someone in the city seemed to realize it, and changed the design of the roundabout. It's better now, but there are still a few areas they overlooked that have the potential to cause accidents.

[Arn_Thor]

I'd really like to know where this was or see some pictures of it. It's almost inconcievable that something designed like a roundabout would be more dangerous. It might indeed cause more accidents due to the kind of confusion you describe, but at the very least the angles and grading should lower speeds dramatically and result in fewer deadly accidents.

[bnralt]

It's set up like this - busy avenue with lanes (left to right) 1, 2, and 3 enter into roundabout with circles (inner to outer) A, B, and C. The problem is that half way around the circle, where the avenue continues, A, B, and C then have lines indicating that you can either continue on the circle or move in a perpendicular direction to the circle and exit back such like this A -> 1, B -> 2, and C -> 3. And that's what everyone does. The problem is If someone from C is going around the circle, they're going to t-bone anyone going A -> 1 or B -> 2, and there's no moment to prepare because A or B is going to be suddenly cutting in front of them.

Or to visualize it another way - if you can image those intersections where there are two right turn only lanes, and one lane to the left of them that's right turn or go straight. Now imagine if all three lanes were right turn or go straight, and everyone made right turns - but if someone in the far right lane is going straight, they're plowing into the cars turning in the other two lanes.

After years they eventually fixed it and made the two outer circle lanes right turn only, which is what they should have done at the beginning. But even there they screwed up, because there's a street that enters the circle right after the right turn only signs, so if someone is entering from that direction and isn't familiar with the circle it's possible for them to ram into the other cars.

[USiBqidmOOkAqRb]

PIT maneuver is not a T-bone. Even if you cut across a lane (from C to A) there won't be enough of lateral velocity to make it potentially deadly. That's one the of the major points of roundabouts.

[Clent]

I live in an area with many A, B, C as you call them. Assuming we're going backwards, where A is right most lane, with these three lane roundabouts it's always A can only turn right, C an only turn left, B is for going straight, but can also turn right or left.

There are variations on this, sometimes, B can only go straight so that C can also go straight. C can also be used for a fully controlled U-turn. In fact, C is has the markings such that one can just go around and around and around forever in if one chose to do so.

All of the roundabouts here have overhead signage leading up to them that indicates which lanes are for each direction of travel. There are also lines on the roads themselves have solid and dashed lines. Never cross solid lines, optionally cross dashes. We get snow so lines aren't always visible.

I've been through many different roundabouts countless times and there is occasionally someone that doesn't get it right but the traffic is moving slowly enough that it unusually only leads to honking.

One strategy is to watch the faces of other drivers, people will be looking in the direction they will be turning.

[Aeolun]

Just because you drove wrong does not make the roundabout bad. That would require you to compare accident numbers from before and after. I’m fairly certain the stats lean in favor of even terribly designed roundabouts.

[bnralt]

> Just because you drove wrong does not make the roundabout bad.

You seem to have misread my post. Everyone drove wrong. I seemed to be the only one to notice it, and started avoiding that roundabout, because driving with the correct right of way rules during busy times would lead you to t-boning another car. Other people I talked to said "no, that's just how you're supposed to drive on that roundabout" (it wasn't, and the signage was eventually updated many years later).

If _everyone_ is driving through it incorrectly doesn't make it a bad roundabout, than I suppose no roundabout can be bad. If it's always the fault of the drivers and never the design, you can't really say 4 way stops are any worse in this regard either.

[Aeolun]

I think you missed my point due to me saying something about driving through the roundabout incorrectly. My apologies, that was entirely besides the point.

I’m trying to say that everyone driving through it incorrectly is not a great metric to judge bad roundabout. If everyone does it wrong and it’s still safer than a regular intersection, then is a success.

Of course I don’t know the numbers involved, so I can’t say if that’s the case here.