It looks complicated from above, but it's very simple once you're on it. It can handle a much higher traffic flow than other kinds of roundabouts. The only potential downside is that you need to know where you want to go before you enter the roundabout. There's no possibility to keep going around until you figure out where you want to go.
(In Dutch, but with images. "Rotonde" is Dutch for roundabout.)
If they're following the markings, yes. We have a 1.5-lane roundabout in my area (two lanes on the north side of the circle, one lane on the south side) fed on the southwest by a two-lane road; the right lane is supposed to be a bypass for vehicles turning right, and does not actually enter the roundabout. Some vehicles still make the attempt, ignoring road markings, adjacent vehicles legally entering the roundabout from the left lane, and even the impending concrete barrier.
The one you linked should've physically separated the right turn lane from the rest of the roundabout if that was the intention. You don't need all that much curb to do it.
In Ontario anyway, the general rule for roundabouts is that you aren't allowed to make lane changes, though they still use a dotted line so as to not make you think you're prevented from entering the inner lane.
Edit: I see it now. Took me a while to see how the inside lane stops at two spots. Interesting design. It ensures that you're only crossing traffic when entering, not when leaving, at the expense of it being less flexible (note how in two directions the right lane cannot be used to go straight through, so signing clearly in advance is much more important).
I hate driving them. Somehow every one I drive on seems massively overengineered, and could have been done with a completely normal single lane roundabout. But it's usually not rush hour when I drive there.
Sometimes there are even no signs/arrows on the road that require you to do it. It is expected of you, but if you happen to be one of the drivers that suddenly change their minds or you don't know how to drive on roundabouts you could continue driving around in the outside lane.
So a typical situation which makes roundabouts dangerous is when you're driving in the inside lane and you want to take the second exit (on a 4-exit roundabout that's going straight). If a driver next to you (in the outside lane) carries on driving until the third exit, they'll crash into you.
If it happens to you in Poland the situation even more stressful, because according to law, you are (partly) the responsible party, because you were the one who changed lanes!
IMHO, that's why turbine roundabouts are a great idea. Too bad that there aren't many of those or they are implemented incorrectly. See . The outside lane ends in only 2 of 4 exits. Is it 50% safer though?
If you want to take the second exit, you should be in the outside lane to start with. In the UK, for a standard two-lane roundabout, unless indicated otherwise by road markings and/or signs the outside lane is for taking the first or second exit, and the inside lane is for taking the third and subsequent exits. You move from inside to outside as you pass the second exit.
There are also rules for indicating correctly that help smooth the traffic flow, but unfortunately many drivers seem oblivious to (or just ignore) them. Also, on smaller two-lane roundabouts more than a few drivers will cut across the inside lane (taking the shortest path) with no consideration for vehicles beside them.
That's how the roundabouts are built where I am from. You can be in either lane and exit from the middle of outer lane. The right lane must exit the inner lane can go around or exit. Although some people in the outer lanes try to turn left and crash into the people in the inner lanes.
I get the difference now, that's how they should be here there would be fewer accidents.
The first few times I encountered a two lane roundabout, I had some concerns about whether you had to cut across lanes to exit in some cases (especially when going straight across the roundabout). But after using it a bit, it's clear that it works pretty well, and that it's no worse than a 1 lane roundabout.
> These designs require motorists to choose their direction before entering the roundabout, thereby eliminating many conflicting paths and choices on the roundabout itself ...
Basically you have to pre-choose your lane before entering as you are not allowed to change lanes once you're inside. With regular RAs you can change lanes if you wish.
That said, my recollection is that the default in the UK is that lanes flare out from the center, so that once you get into the lane you don't have to switch to another to exit.
You're not wrong, but roundabouts degraded the busier they get:
> As at other forms of unsignalized intersection, when traffic flows on an approach exceed approximately 85 percent of capacity, delays and queue lengths vary significantly about their mean values (with standard deviations of similar magnitude as the means). For this reason, the analysis procedures in some countries (Australia, Germany, and the United Kingdom), and this guide, recommend that roundabouts be designed to operate at no more than 85 percent of their estimated capacity.
1-, 2-, and 3-lane RAs each have different capacities, and it may not be easy to expand one size to the next larger one depending on what else is in the area, so signals can allow for the general architecture of RAs to be extended without major changes besides putting up some poles and wires.
In the UK there are road markings that indicate a similar flow, but this turboroundabout makes it physical.
* Raised curbs force the outside lane to exit.
* After each exit, there are only 2 lanes left.
* After each entry, there are 3 lanes, a new one starts from scratch on the inside.
Although it appears that Dutch traffic design tries to avoid intersections with more than 4 directions. Better merge a couple of them before the intersection.
I grew up by this roundabout; the south exit joins to a village. Note it has 5 exits, and is slightly tweaked: there are two lanes that go off most of the exits, except the village exit has one lane and actually going off is optional. Every major entrance to the roundabout has four lanes so you get in the lane you want for the exit you want. The minor entrances have fewer lanes so you just sort of race into the lane you need.
Oh, and it has traffic lights as well.
I assume that traffic on the loops always has the right of way over traffic trying to enter the loops?
In that case, why can't you keep going around? At the place where the northbound inner loop becomes the southbound outer loop, it crosses the start of the southbound inner loop. The cars coming from the south trying to enter the southbound inner loop have to yield to the cars on the northbound loop, so it should be perfect safe for those cars to turn onto the southbound inner loop.
Note that allowing this maneuver is necessary if you want to allow eastbound or westbound travelers to make U-turns. If it is not allowed, then only northbound or southbound travelers can make a U-turn on this.
I also disagree that it is simple while you're on it although I have to admit that I'm not a very confident driver at the best of times so maybe that's just me.
What makes it confusing is, I think, the overhead signs in the roundabout. It would be easier without them. Because the arrows pointing up also points towards the incorrect exit at the same time due to the round nature of the road :)
In a "traditional" roundabout, all motorists could perform an extra round and thus clear the roundabout fast and easy. This doesn't work that great in these kind of roundabouts, I guess.
Q: Is such a construction grade-separated and/or are the separate flows in controlled by traffic lights? The diagram isn't that clear...
It looks like a roundabout, it feels like a roundabout but the priority rules are reversed so if you treat it like a roundabout it only ends badly..
See also sub-section in the main EN page:
However, yes, complicated roundabouts that require perfect knowledge of what lane you need in order to take an exit you can't see in advance do suck. If you find yourself installing a roundabout with more than one lane, you probably should be installing a traffic light instead.
Early mergers are the assholes. You're SUPPOSED to merge late. If you see a sign saying "Construction ahead 3 miles, left lane closed" or something, and you immediately start trying to merge, you're the one doing it wrong.
Early merging creates unpredictability in traffic flow. Zipper merges are safer and lead to shorter merge queues. https://en.wikipedia.org/wiki/Merge_(traffic)#Zipper
Starting to go off topic, but I'm starting to feel I'm the only person the never refers to a lane change as a merge when it isn't a part of a lane ending. IMO, a "merge" should only refer to lanes ending. Otherwise, fighting about "late merging" becomes ambiguous.
Folks commenting on this, thanks for the correction but also you should have picked up from the context (of a tornado roundabout) that I was referring to a lane change.
He told me it was a 'nightmare', and 'weird' and so on. I was actually pretty underwhelmed when I drove it - it seemed really logical to me, and it was a bit of a non-event - I was expecting some kind of white-khuckle 'driving in Marrakech' sort of experience. I think people's perceptions of it are significantly different from reality, but maybe that's because it makes sense to me, but if it's as safe as they say it is, maybe not...
It's true it has a good safety record if you consider fatalities/injuries. But that's because it's impossible to cross it at speed unless it's completely empty.
I suspect its record for minor collision damage is less reassuring.
The fundamental problem is situational awareness. On a normal roundabout you only have to look in one direction. On the magic roundabout you have to be aware of traffic from the left, right, and front - and if you're not a regular user, you have to do this while trying to navigate the design.
Although it is a bit intimidating the first time you use it (especially if you are from a country that doesn't have many roundabouts) the locals like it. It works very well and the traffic keeps flowing even at busy times. They even put the fire station right on the roundabout. ;0)
Caveat: I am talking about driving around it in a car. I wouldn't want to cycle around it when it is busy.
One of the hardest things in local democracy is that the best traffic patterns are often also traffic patterns that are unpopular with motorists. Sometimes that is directly linked (e.g. “road calming” where narrowing the road forces drivers to pay closer attention to their surroundings) and sometimes it’s just that the aggregate statistics are counter-intuitive (e.g. “road diets” where trading 2 lanes in each direction for 1 each direction + center turn lane often has no impact on total throughput).
Governments and safety organizations are pushing for "Vision Zero", i.e., safety at any cost. (My economics professor once pointed out that if you really want zero traffic deaths, just limit all cars to 5 mph everywhere.) For people driving on the road, the current level of risk (roughly 1 death per 100M miles) is acceptable, and arriving quickly is desirable.
Once you get to the point where the numbers are really tiny, safety is hard. It's tough to make people follow procedures when they've never seen any problems from violating them.
I see this effect happen with software, too.
I definitely find myself taking slightly longer routes that let me avoid stressful situations, e.g. turning left onto a busy road.
(It is an explicit component of Vision Zero that improved safety should not be expensive to communities.)
Pedestrians don't really feature from a safety perspective because there are light-controlled crossings all the way around the fringe. The problems I saw were when arrogant/impatient people (as opposed to first-timers) saw a gap that was intentionally left because of the way traffic flows from one roundabout to the next, and would speed past two or three cars then push in. But those people cause problems everywhere.
Also the football ground on the corner doesn't help when 1000s of people all arrive at those lights at the same time it can cause chaos.
It is about 8 lanes across, with no lane markings, and with vehicles entering the roundabout from one of 12 junctions having right-of-way.
I'm not sure what was happening on the day the Google maps aerial photo was taken, as it unfortunately it doesn't show the chaos that normally ensues.
Having taken that roundabout in just about every way possible (car, scooter and yes - velib), I can only recommend to anyone on it to have fluid yet determined movement on the roundabout.. even if you don't quite know where you're going or if the next exit is the one you really want to take. A fun exercise.
It is spectacular for being such a point of interest for visitors and to then be so unfriendly to our squishy bodies and a rather unpleasant assault on the senses.
As we went through the Hemel Hempstead magic roundabout in the back of a cab, he turned to me and said "Okay... you might have been right."
(And Canada is already among the safest non-European countries, with significantly fewer fatalities compared to the USA)
But let me tell you, the first day driving on the other side of the road is a real doozy. And I nearly died a couple of times. And I was doing my very best to avoid "magic roundabouts".
(I actually drove all week through rural Wales, which was a different kind of adventure)
Swindon is a weird exception for using the blue mini-roundabout sign on this type of junction. I think that makes the junction look more confusing than it really is.
But I'm pretty fearless these days!
The Colchester equivalent better demonstrates this:
Personal anecdote: I had to drive around one of these junctions during my driving test
There are lights to make sure nobody crashes - effectively switching it between being a roundabout and being a through road - but it's still pretty weird.
The problem with Colchester is that it's plagued with heavy traffic and bad drivers.
It's much more dramatic near Dover: traffic is channelled from the port straight into a bunch of roundabouts. My dad was metaphorically scarred for life after disembarking a ferry with his Italian campervan in 1986.
I moved from the UK to the US in 2001. I then learned to drive in the US (Had no need to in the UK).
Sometimes I dream of the UK, my dreaming brain realizes I'm on the "wrong" side of the road. So it tries to switch me over, but that means traveling to the US, so I then have to get on a plane to... drive on the right side of the road. I do it less now that I'm aware of what's going on, but it was very disconcerting to wake up from!
Actually driving in the UK (while awake!) is much easier, as you're just kind of following the flow of traffic.
In particular I've found that driving on the continent in a UK car is a lot harder than driving on the continent in a local hire car, beyond the lower visibility you get when merging etc.
1. Scaring people into slowing down is a viable way to avoid accidents.
2. Perceived scariness of an intersection is not indicative of how dangerous it actually is.
Absolutely. Within Saskatchewan, east of Regina, we just completed three new bridges for suburban communities to access the main highway. In two of the three bridges were atypical designs using a Diverging Diamond at one point, and dual roundabouts at the other.
When announced lots of people were fearful of the new designs and there was unsurprisingly a lot of outcry from ninnies who were afraid of the unknown. There's been a couple instances of people taking improper directions on the bridges but they're typically by elderly drivers who probably shouldn't have been behind the wheel in the first place.
I personally have my own qualms with the design of one of the bridges but that's outside this discussion. I like the concept enough that I hope to see them use diverging diamond more and more roundabouts as people get used to the efficient flow.
I think the fear aspect comes from the fact that hitting a pedestrian seemed like a real possibility the entire time I was in the town. But that fear is rational: there is a real possibility of hitting a pedestrian, and a high-foot-traffic area shouldn't be designed to assuage that rational fear. Drivers should be afraid of hitting pedestrians.
A placard commemorating the redesign in the town square said that since the redesign in 2017, car/pedestrian accidents dropped from 279 to 43.
* I'm citing numbers and locations from memory here so take this all with a grain of salt. I only stopped in the town for lunch on a long drive, so I don't remember all the details. My memory for numbers is usually good, but is not infallible.
Is it possible to get (Google?) Maps links for these?
The Diverging Diamond: https://firstname.lastname@example.org,-104.4361408,553m/da...
The Double-Roundabout: https://email@example.com,-104.2845914,552m/da...
The standard design: https://firstname.lastname@example.org,-104.3603897,781m/da...
Webpage of the project with some more info: https://www.reginabypass.ca/project/map-facts/
EDIT: If you drop yourself down into street view it looks like you can see how the designs are laid out. No satellite view yet though
Result lower accidents, much lower speeds, and above all safer cyclists, pedestrians and any kids playing.
They look insane on a map, they must have been hellish to navigate before GPS.
 As an example https://email@example.com,2.1491456,232m/data=...
This example is by no means the worse in the UK -- far from it -- but it does illustrate how cars can be going round at high speeds even when it's not really safe to.
It amazes me there aren't any fatalities on these kinds of junctions because it's a horrible mix of speed, heavy traffic, lighter and heavier vehicles (eg you get plenty of lorries on there too) and clueless drivers. A real bad recipe. But it might just be my lack of faith in other drivers that makes me nervous on those junctions rather than them being inherently unsafe.
> Despite opposition to his concept from many in an engineering profession known for its conservatism, his roundabout designs were formally written into government design manuals in 1975. By this time his experiments had become increasingly radical. Among these were the “magic roundabout” in Swindon in 1972 and multi-ring junction in Hemel Hemp-stead in 1973.
> Such junctions comprising as many as six mini-roundabouts — like a series of cogs in a piece of industrial machinery — did cause some chaos when first encountered by bewildered motorists. But Blackmore proved that the multi-roundabouts reduced speed, increased through-put and aided traffic flow. However, the idea was perhaps one step too far for an incredulous engineering profession, and it never really caught on.
The country was slowly recovering from this. All indications are that we're due for a reboot, if the brutalist-light towers popping up all over Manchester are an indication of things to come. The new government is also led by a figure notoriously thirsty for bold statements in public works (garden bridge, estuary airport, bridge to Ireland, etc).
I haven't read it for a while, but I think there's an explanation in the book from the printing company -- they wanted to test out their new colour printing press, so sent someone round the industrial estate with a camera and made a calendar. Potential clients were given it as a sample, but they then received requests to purchase them, and eventually made the book.
I also encountered a T junction with three lanes in each direction and traffic lights. When the lanes coming from the bottom had green lights they were one right and two left, and at the same time the rightmost lane coming from the right had a green light to go straight. Three inputs and three outputs, but sure surprised me. Traffic patterns are very local and often undocumented. Just like code.
My favorite roundabout ever is a large traditional one with only two entrances/exits. Reminds me of a lot of codebases I've encountered.
If it's a multi-lane roundabout, it's important to use the correct lane. Other drivers will expect someone in the appropriate lanes to stay/exit the roundabout accordingly.
If you're about to turn off then be on the inside lane. If you're not turning off then be on the outside lane.
i.e. join on the outside lane if you're turning off immediately and join the inside lane otherwise.
>however, the roundabout provides a better throughput of traffic than other designs and has an excellent safety record, since traffic moves too slowly to do serious damage in the event of a collision.
Personally never witnessed an accident, but I have heard of them.
They tend to be caused by indecision or drivers speeding -- drivers that think that they have a right of way i.e when everyone has stopped, two people go onto a mini roundabout at once.
I think the whole point of the design is that there are fewer accidents at the same time as higher throughput.
Plus, the Canadian design of putting the pedestrian crosswalk, right at the roundabout and having cars stop in the roundabout to yield to a waiting pedestrian adds additional risk.
The only disturbing aspect it brought to my life wasn’t navigation stress, but rather its unpredictable effect on my commute. :)
I don't drive, so I wasn't unsure, just terrified, as you would be if you being driven round it by my then girlfriend, who combined the driving skills of a rally driver with the mentality of Mr Toad from Wind In The Willows.
NVM: Found the answer in the wiki. http://news.bbc.co.uk/2/hi/uk_news/england/london/7140892.st...
The only difference between this and a "normal" ring road with round-abouts is that the distance between roundabouts is 50m not 5km :)
The signage is surprisingly terrible too, often appearing only after you're more or less committed to your lane because the one you're supposed to be in is bumper to bumper and stopped.
> In 2010, the National Cooperative Highway Research Program concluded that the roundabout reduces injurious crashes by three quarters
Since you seem to find it fit to question if I read the article I may as well question whether or not you even read my comment.
I specifically mentioned the article's claims about injury reduction (which I don't doubt). How could I possibly question what is omitted from those claims (overall accident reduction) if I didn't read the article to read those claims in the first place?
Subsequent trips were easy. If you're intimidated, just get on it and stay on it until you feel like you get where it's going. Those crossovers are dodgy AF though, especially with irate lorry drivers who are, most likely, also pretty stressed for having to do the thing ..