I live in PA but I work in Owings Mills, so I’ve been going through that roundabout ever since they made it.
Before that, I had to go through Hampstead every day. The bypass is MUCH better.
Green Bay, the city where I grew up, has had a crap-ton of roundabouts installed in the last decade-plus. When I was up there for a visit last year, I was trying to drive to a store I’d not ever been to before, on a street that wasn’t there when I grew up – usually, if I know roughly where something is, I can navigate there on my own, thanks to still remembering where things were/are.
The route to get there went through several consecutive roundabouts, and even though I was using Google Maps on my phone, it simply wasn’t able to give me new directions quickly enough to get me through the roundabouts. By the time it’d say “exit the roundabout for Street,” I was already past that exit. I felt like Chevy Chase in *National Lampoon’s European Vacation," stuck in a London roundabout for hours.
Here’s a scenario that’s similar but not exactly the same.
If the 3 lanes in the roundabout are numbered 1, innermost; 2, center; and 3, outermost; then if Car X is in the roundabout in lane 1, and Car Y wants to enter the roundabout to either lane 2 or 3, does Car Y have to wait for Car X to clear before entering?
If the answer is No, then technically I see that as a true yield because Car X is not in the lane that Car Y wants to enter. However this might seem a little hairy, because it might appear as if Car Y is ramming into Car X only to turn into an outer lane at the last moment. Could be a bit dicey.
If the answer is Yes, that Car Y has to wait for Car X to clear first, that would mean there is extra required waiting for the roundabout as a whole even though the outer lanes are not occupied.
This scenario differs from what @Lord_Feldon said in that Car Y does not need to cross into the path of Car X. However, it appears from what they said that the answer to the question is Yes, Car Y has to wait for Car X to clear the space in front of them.
Notice that my scenario includes these possibilities:
- Car X in lane 1, and Car Y wants to enter and use either lane 2 or 3.
- Car X in lane 2, and Car Y wants to enter and use lane 3.
This scenario is missing a key fact: the lanes aren’t fixed, but rather spiral outward. At every exit/entrance, the outermost lane must exit, the middle lane becomes the outer, and the inner becomes the middle. A new inner lane starts where the cars are entering.
So a car entering for the inner or middle lane must yield for all cars in the circle except those exiting. Cars entering for the outer have to yield to those in the old middle/new outer lane. They may or may not have to yield to those in the old inner/new middle. I’m not sure, but I would guess not.
However, note that there are different kinds of turbo roundabouts and only the one called a Rotor turbo has the characteristics I described above. The Hollister roundabout is a Rotor. The Federal Highway Admin has a pamphlet describing the various kinds (you’ll have to look at the pamphet to see the figures):
Thanks for the pamphlet. Am reading…
Well it’s not like the “Yield” sign that means you do not have the ROW even if on the right is entirely alien – we see it in highway merges and on/off ramps all the time. But the 'Murican drivers do not seem to get the implicit “…by stopping if that’s what it takes” part. Instead they view it as “you’re gonna have to either slightly slow down or heartily speed up to snake your way into a traffic flow that left to its own will NOT accommodate you”.
Plus, sure, they all suffer from the Griswold Panic that they’ll never get through if they have to always yield to “everyone” (or that then they can’t just &^%* cut lanes like God meant to get where they want to be).
FYI, the Wikipedia article on roundabouts has a diagram showing possible collision points in a conventional two-lane and a turbo roundabout.
That doesn’t appear to be a completely equitable comparison; in the righthand diagram it seems like people can only turn right or go straight ahead - a 270 degree (or more) traversal of the junction seems like it would be very awkward at best.
Edit - I’m looking primarily at the top left corner (although the bottom right is the same) - if a vehicle enters from the right side of that diagram and wants to exit to the bottom of the diagram, how do they get around the top left corner?
Second edit: OK, maybe I see it - they get into the outermost lane and stay there until they exit. It just feels weird, but that’s probably just because I’m accustomed to something else.
The problems with roundabouts (which this one seems to amplify, not improve) is the merging. In my experience, American roundabouts have too small a turn radius. Unless you;re going reallllly slow everything happens fast. The ones by me give you about two car lengths to know if you’re in the wrong lane, and pretty much unless you drive it every day, you are.
The cars come up fast. With the turbolaserstealth roundabout you don’t have to watch one or two lanes, you have three! And you might have to cross all three. Is that guy coming around, or taking the turn? Who knows! Better wait. OK he turned, but here comes another car! next thing you know five minutes have gone past and the people behind you are impatient.
In the rain or at night, it is difficult to judge distances. People are going to wait too long, or pull out in front of someone. And trucks are going to hold the whole thing up.
Even if the above are things you can adjust to, roundabouts in busy intersections are stupid. If there is a constant flow, you can’t get into them. I don’t know how busy this one will be.
And is it just me, but that video sounds like one for the Turbo-encarbulator. 
The best thing in freeways is how they started painting in the lanes where they go at the big interchanges. It really helps when you’re not familiar with the area which lane will exit to I75 south and which one goes straight. And they paint them usually far enough back that you can adjust even in traffic. (usually. Ask me about my long trip around San Antonio!)
If it weren’t so bloody expensive, adaptive traffic lights would be the better option. As in they get an idea where the traffic is either by noting each time a car goes over a sensor in the pavement and estimating when and how many vehicles will be arriving at the next light, or using Google’s traffic data. I am not aware of any municipalities which do this, tho.
I am an American living in Spain. My town of over 10,000 people has no traffic lights, just roundabouts. The city nearby, slightly larger, has one traffic light. Roundabouts are much more efficient, especially in light traffic.
The highway interchanges have roundabouts at the bottom of the exits. Sometimes they is one right after another. It all seems to work well. Large cities, like Madrid, have a mix of roundabouts and traffic lights. Usually more of the former than the latter
I don’t have much to say about the turbo roundabout, but I hope it appears in a future Road Guy Rob video. You wouldn’t expect videos about traffic engineering to be fun, but his videos actually are.
Hi @Guapo what has your experience been with them in heavy traffic?
I am not Guapo, but one weakness of roundabouts can be that if there’s a lot of traffic from one direction in particular, cars from other directions can get locked out.
When this is regularly the case, traffic lights typically get added. This might seem to defeat the object of having a roundabout, but in most such cases the traffic lights are just for a subset of entry directions, so it is still more efficient than a wholly traffic-light based system. Plus a roundabout can connect n directions, rather than only 3 or 4.
They are also often only on for limited times. For example, just after quitting time of a large nearby factory.
It’s rare for a true roundabout to have more than 5 legs. Not saying it doesn’t happen, but it’s not very common. And when they do have more than 5, the roundabout is virtually always an unusual shape, such as an oval or peanut. Rotaries, which in some ways are the opposite of roundabouts, have more than 5 legs much more often.
I haven’t experienced any turbos, but overall traffic circles (what we call roundabouts) work well in New Jersey and they alleviate congestion at a lot of intersections.
The larger, older circles still have problems but the newer small ones have been great. Much faster than traffic lights and 4 way stops.
But maybe they work better in NJ as we’ve always had circles and they aren’t something new being introduced.
I learned to drive in Boston, so I can get aggressive when needed. But I don’t think it’s any worse than the gridlock that can occur with traffic lights. As someone else mentioned, you can combine them with traffic lights when needed.
Note that traffic engineers call the larger, older circles rotaries, and the newer, smaller circles, roundabouts. There’s several differences besides their size:
- Rotaries were intended to keep traffic moving at about the same speed (often 35+ mph) while roundabouts require traffic to slow to about 20 mph.
- When first invented (late 1920s/early 1930s) rotaries generally had no traffic controls. Traffic was meant to follow the basic rule at intersections which meant yield to the right. That is, traffic in the circle yielded to entering traffic. (The Yield sign, by the way, was not invented until about 1950.)
- Traffic entering rotaries often had to change lanes to get in. And then change lanes to get out. This caused lots of conflicts (and thus accidents) especially during times of heavy traffic.
BTW, lots of rotaries have had their rules about who has the right of way changed in recent years to match the roundabout rule that traffic already in the circle has the right of way. Not all of them; there are still some that have yield or stop signs pointing at the circulating traffic.
Officials in my county are now receiving complaints from local grain farmers who say a new roundabout at a rural intersection was constructed too small for their big rigs to navigate.
I’m generally pretty ok with roundabouts, which are slowly but steadily increasing in number here in Maryland.
We call all of 'em rotaries in New England, and common consensus is that cars entering the rotary yield to cars already in the rotary. Anyone who stopped in the rotary to allow another car to enter would be dragged from their car and pummeled. I have no idea what the official rule is, but in daily practice, cars entering yield to cars already inside the rotary.