A half an hour away from us, a brand new “turbo roundabout” just opened, only the second in the country. We’re well used to regular roundabouts, but I’ve never heard of this kind. We’re going to have to go try it out.
It looks a bit complex, especially that innermost ring. Hopefully folks will get used to it without too much turmoil. That intersection has been notorious for accidents and it’d be nice if this solution reduces them.
What do you think?
Idiots are going to idiot.
Around my parts folks struggle with standard roundabouts. I’m not sure this is a great idea.
And it may just be me, but that is one annoying video.
mmm
We have a roundabout near here that is kinda based on the same idea but it’s a bit simpler and it doesn’t have the hard lane dividers. When it first opened it was a death trap because people wouldn’t pay attention to the signs. It’s a lot safer now that everyone is used to it, but an important consideration is that it’s on a road that gets almost exclusively local traffic.
The hard lane dividers will probably help to prevent a lot of the issues that we had, but I can picture a lot of folks crossing lanes just before the dividers because they either misread or weren’t paying attention to the signs and ended up in the wrong lane.
I think it clears up one of the problems a lot of people have with the current multiple lane roundabouts which is they are unsure of when they can/should change lanes while in the roundabout. This seems to clear that up by putting you in a set lane from the beginning which you just stay in till you exit. They only basic rule to follow it to yield to traffic on your left while entering.
For a 4-way roundabout it makes it rather simple. Exit 1 is the right lane, exit 2 center, and exit 3 left lane.
Still doesn’t solve the moron driver problem though. The same people who will practically stop in a center lane so they don’t miss their freeway exit are the same ones who will freeze in the roundabout when they realize they didn’t choose the correct lane and then try to jump lanes.
That was my reaction. This looks very cool. I wish it was viable at every intersection. No more waiting at traffic lights!
The weird scallops in the central island seem a bit pointless - if you are using the roundabout to make any 270 degree turn, then you have to traverse three quarters of the circumference of the thing, and that appears to involve moving across one lane at some point in the process, but the sticky-out parts of the central island seem to make that awkward.
To be clearer: the vehicle on the green path - traversing three quarters of the roundabout, has to cross all three joining lanes where cyan and yellow are joining, in order to merge into yellow’s lane:
It might have been better if, instead, that merge took place into cyan’s lane, leaving yellow to make a right turn that is unmolested by any merging traffic., but green merging into cyan’s lane requires green to move inward one lane, toward the central island, and the scallops in the island are clearly designed to thwart that.
Nowadays there will be lots of accidents until Google maps and Apple maps have been updated so the navigators can correctly tell the drivers which lane to be in and when to turn their steering wheels left or right. Lotta folks cannot drive any more; they can only follow the verbal orders from their computer.
For the folks using the nav system built into their car that isn’t updated, they’ll be crashing forever. But at least that’ll be removing those cars from circulation.
Studying it further, there seems to be no provision for using the thing to make what amounts to a U turn to go back the way you came. Also, if you accidentally entered the wrong lane at the beginning, there’s no option once within the roundabout for getting over to the lane you intended without crossing the lane barriers. I think.
The point is that the lane shifting is built into the design. For every 90 degrees of rotation through the roundabout, the lanes shift right by one lane. When you enter the roundabout, you choose which exit you are taking (90, 180, or 270 degrees) and get in the appropriate lane. Since the lanes shift every 90 degrees, at each intersection thereafter you just drive straight through the intersection until your lane exits the roundabout.
It’s clever, I’ll give them that. But it also absolutely requires you to choose the correct lane when you first enter the roundabout. If you choose wrong, too bad. You’re taking the exit that you chose, whether it’s the one you really wanted or not. It’s completely unforgiving in that respect.
We’ve had roundabouts in our area for maybe 15 years now, and idiot drivers still can’t figure it out. Even the simplest roundabouts- perpendicular crossroad; 2 lanes per direction; inner lane turns left or stays straight, outer lane right or straight. Don’t know how many times I’ve been in the inner lane, intending to go straight through, and someone next to me in the outer lane makes a left, cutting in front of me, causing me to slam the brakes to avoid t-boning them.
One particularly busy roundabout got so notorious for accidents that they put up a fence with some blackening material to reduce visibility. The head-scratching logic there was that it was thought people were being too optimistic about their chances to jump out in front of traffic and entering the roundabout too quickly, so the reduced visibility was supposed to slow cars down and increase caution.
That turbo-intersection looks like it will be a nightmare, if the skill level of the drivers in that area is anything like around here.
Green shouldn’t be moving into cyan’s lane. The only reason to do that is if you are doing a complete U-turn through the circle, which this design does not allow.
That’s a feature, not a bug, from my perspective. I hate when drivers commit to a lane or off ramp, discover they made the wrong decision halfway, and decide to rectify, the rest of the traffic be damned.
Sometimes you just have to finish out your mistake and hang a u-turn when you can.
I know green shouldn’t merge into cyan, according to this design, but that’s what I am saying is a potential pitfall, because it means all three joining lanes are giving way to green.
Protecting yellow’s lane so that it is exclusively a right turn lane, might be better.
It’s a neat idea and looks good in the video and probably on paper. But concepts like this sometimes struggle when contacting reality. The Valencia Street bike lane in San Francisco comes to mind. In this traffic circle, the people going left still need to cross thru a lane of traffic already in the circle (and are supposed to yield), but with a high volume going thru there it may take a while, and drivers will be impatient - perfect set-up for a t-boning.
I know this intersection, and I suspect the reason it was so dangerous is because of the high volume of traffic on both roads trying to be controlled by a traffic signal - the wait was long if you got the red so people risked running it too often. IMHO this is a cheap and temporary fix where a proper grade-separated interchange is warranted.
Perhaps I’m more familiar with the general concept of roundabouts than the average American (from the UK originally). But without having seen this design before, it took only a few seconds to understand how it worked. Not bragging, rather saying that I think it implies that this is a good intuitive design.
I don’t think it’s so unforgiving as you suggest, because you can enter in two out of three lanes for two out of three trajectories. To turn right you can be in either the right lane or the center lane; to go straight you can be in either the center lane or the left lane.
To turn left, strictly speaking you should only be in the left lane; but if you are in the center lane, it does appear that there’s an opportunity to correct and switch lanes inward if traffic is not too heavy after the first quarter turn - at the point where new traffic is entering and there’s a gap in the divider, and where you have right of way over that entering traffic. It’s hard to tell whether accommodating that course correction at the only plausible gap is an anticipated feature, and how much disruption to traffic flow it would cause in practice. A similar inward lane correction would allow you to do a complete 360 and exit where you entered.
My guess you’d complete the circle waiting to changing your lane to the correct one where the the dividers open up at the intersections. May have to slow down or gun it to make the switch.
I think these traffic circles are awesome.
There’s always a way to take a bad idea and make it even worse.
I wonder how Americans would react.
This roundabout is like democracy, it’s great if everyone is smart and paying attention. That’s why it wouldn’t work well in America.
We will certainly transition to more complex arrangements that improve traffic flow when the AIs take over completely and fallible human driving is banned.