They absolutely are. Even if they don't prevent all collisions, they turn T-bones into glancing hits and so save a lot of lives. The worst roundabout beats the best 4-way stop any day of the week. Sometimes there really are easy answers.
> 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.
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.
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.
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.
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.
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.
> 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.
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.
I think they're a bad design as they encourage drivers to go fast with the sweeping corners etc. Ideally, a roundabout should be designed to slow traffic joining it to reduce collisions and their severity. Trying to keep vehicles moving quickly at junctions is just asking for trouble.
The one I linked to in Fairfax County VA also has lights, though it might not be obvious from the aerial view. It's really a disaster of traffic engineering. It's probably the most complicated intersection I've ever driven through.
You can actually screw them up: by our house (in California) they replaced a 4-way stop with a roundabout with no signaling on 2 of the ways, and a stop on the other 2. An absolute disaster, as the 2 ways without the stop assumed they had the right of way over people already in the roundabout.
After the neighbourhood complained, it's now a roundabout with 4 stops (not ideal, but not dangerous either).
This. If it's not the case that all entrances have a Yeild (what we call "Give Way" in the UK), it's not a normal roundabout.
The feature that seemed to be missing from the roundabout in the original post was any kind of signage. Normally in the UK, roundabouts have a sort of map view as you approach them, then on the islands are signs telling you where to exit.
I can confirm these are dangerous. There are several of these in Berkeley and I got knocked off my bicycle on one of them for exactly the reason you describe.
I am from the UK and it makes me wonder why road design in the US is so bad. Just one minute of thinking about this as a lay person would reveal the problem with the design.
Is there some structural reason in the US that would cause it? Perhaps some lack of standards or approval process? Perhaps iteration speed is slower so they don’t get better? Some other incentives going on?
My personal hypothesis on this is that the worst 5% of Americans is likely both dumber and more sociopathic than Europeans, and the behavior of the worst drivers is what creates a lot of traffic and road accidents. If that is the case, you will not have the same kind of design that works in a high-trust, more cohesive society.
What should I imagine when you say roundabout with 4 stops? Isn’t that just an intersection that looks like a roundabout without functioning like one (entirely negating the point)?
I guess drivers just don't realise they need to slow down or give way to anybody unless there's a stop sign, traffic light or they're turning into a different road.
Surely drivers know what Yield means though right? I guess the US might need yield signs at a roundabout given not all drivers will get the basics of how they work. There should never be a stop sign on a roundabout, the whole point is you're supposed to be able to keep going without stopping at all if theres nobody coming round it.
No easy answers, no solutions only trade-offs. Perhaps better for safety, but they makes crossing as a pedestrian longer and harder. And while intersections designed for roundabouts can be pretty smooth, retrofitting undersized roundabouts into intersections designed a 4-way makes for ugly and difficult to navigate messes.
I like them, but it is a mistake to blindly install them anywhere possible.
What's wrong with mini-roundabouts? We've got lots of them here in the UK, mainly in residential areas and I don't see the issue with replacing a 4-way stop intersection (U.S. style) with a mini-roundabout. All that's needed is to remove the STOP signs and splash a bit of white paint onto the road to mark the mini-roundabout. Optionally, build up the mini-roundabout to make it harder to drive over.
In most of the world, unless the intersection has pedestrian features (like traffic lights with green men or islands with pedestrian waiting areas), it's better to cross the road away from the intersections. Then you only have 2 directions of traffic to worry about. AFAICT, in the US, crossing away from the intersections is illegal in many cases.
When Cycling and approaching a roundabout move to the middle of the lane and follow the same routes as a car. Yes you slow the cars a bit but they are supposed to be going slowly anyway. If you don't want to do that, you can get off your bike and cross as a pedestrian would.
Roundabouts not good for pedestrians and cyclists. In London we’ve been replacing roundabouts with other types of junction to improve pedestrian and cyclist safety.
We don’t have four way stops though so instead it’ll be min/maj junction or traffic lights.
This is only true of typical UK-style roundabouts which are designed for motor vehicle throughput.
It’s extremely common in the Netherlands to replace crossroads and T-junctions with roundabouts to improve safety, but Dutch urban roundabouts are designed with safety as the main priority. This is achieved through single lanes, sharp entries, limiting forward visibility, and pedestrian and cyclist priority (via what are effective zebras).
We should absolutely be deploying these where we can, but they do take up a lot of space relative to their traffic throughput, and are only really suitable for a fairly narrow range of traffic volumes.
NL seems to quite commonly have this kind of physically large but medium traffic suburban junction, but outside of Milton Keynes and the outskirts of some towns that got heavily developed in the 60s, it's hard to see many places where we could just drop it in.
> That the Dutch roundabout, including the cycle tracks all around it, can be built in almost the same space of a traditional junction is the reason why so many are being converted.
In some cases, I see roundabouts used in places a stoplight would be much better. It isn't roundabouts vs 4-way stops, its roundabouts vs a whole bunch of other options.
