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Magic Roundabout (Swindon) (wikipedia.org)
163 points by franze on Jan 23, 2020 | hide | past | favorite | 194 comments

A better solution for high traffic flow is the turbo roundabout[0] which is getting increasingly popular in Netherland. Before you enter the roundabout, you select the lane for the direction you want to go. You only cross traffic when entering the roundabout for the first time. After that, you simply follow your lane and it delivery you where you want to go.

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.

[0] https://nl.wikipedia.org/wiki/Turborotonde (In Dutch, but with images. "Rotonde" is Dutch for roundabout.)

I don't understand how the turbo roundabout is any different than a typical two-lane roundabout. It looks like a regular two-lane roundabout from that picture in your link.

Isn't a two-lane roundabout one that simply has two lanes going round? The thing about the turbo-roundabout is that there are actually no lanes going round. Each lane just takes you to your exit. There's no option to stay on the roundabout at that point: you're forced off. It's very restrictive in that sense, but that also means that traffic flows smoothly: other drivers also have no option to merge wrong or try anything weird.

> other drivers also have no option to merge wrong or try anything weird

If they're following the markings, yes. We have a 1.5-lane roundabout in my area[1] (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.

[1] https://www.google.com/maps/@42.0332849,-91.6029348,100m/dat...

In turbo roundabouts, the markings are usually delineated by raised curbs.

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 a traditional 2 lane roundabout you aren't forced out of the roundabout. An example would be https://www.google.com/maps/@39.9561738,-86.1623079,150a,35y...

Are you just talking about being able to make a lane change within the roundabout? Because the outer lane cannot take the third exit in your example (at least according to the lane markings), they must exit before then.

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).

On these "turbo roundabouts" there are also kerbstones between the lanes, not just lines. You can cross them but it'll be obvious that was not the intended use.

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.

On a plain 2-lane roundabout when you're driving the outside lane you are not forced to leave it at the 2nd exit.

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 [0]. The outside lane ends in only 2 of 4 exits. Is it 50% safer though?

[0] https://www.google.com/maps/@52.2547072,20.9822988,188m/data...

> a typical situation which makes roundabouts dangerous is when you're driving in the inside lane and you want to take the second exit

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.

In a regular two-lane roundabout, this difference is arbitrary. Your second exit is the third exit for cars entering before you and the first exit for cars entering later. If someone is entering from your exit, you may still be in trouble when you try to move to the outside lane after the second exit. Hence the turbo roundabout.

The difference is that, on a turbo roundabout, when you're on it, you're not allowed to go straight when on the right lane. Right lane is only for exiting the roundabout, while left lane is for either exiting or going forward to the next exit. This contrasts with the regular roundabout, where if you try to exit from the left lane, you are risking collision with someone on the right lane who's not exiting.

> This contrasts with the regular roundabout, where if you try to exit from the left lane, you are risking collision with someone on the right lane who's not exiting.

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.

I'm not seeing the difference between this and two lane roundabouts. We have a bunch of these in the southern suburbs of Minneapolis/St Paul, and they work well even on roads with moderately high traffic. My only issue with them is that I find them somewhat scary as a pedestrian during winter.

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.

https://www.google.com/maps/@39.9561738,-86.1623079,150a,35y... is a "standard" two lane roundabout. Roundabouts like https://www.google.com/maps/place/Minneapolis,+MN/@44.883386... are more similar to a turbo roundabout but does not force traffic out after 3 exits or less, the inner lane could be followed indefinitely.

On that second link, I don't see any roundabout at all. It looks like a regular intersection to me.

Maybe the aerial imagery is out of date? It looks like a regular intersection on the satellite view, but Google Maps has it marked as a roundabout.

This is interesting, I seem to be getting newer aerial imagery than either of you https://i.imgur.com/tC6fsQm.jpg

If you switch to globe view, the image changes.

Yep that's it, globe view has the newer image and legacy mode has the older image.

Took me a second look to see it, look at the diagram in the Wiki link. The inside lane physically becomes the outside lane at two points, meaning you don't have to cross a lane to exit like you would sometimes need to in a "normal" two-lane roundabout.

On a regular two-lane roundabout some people don't use the inner lane when they want to go left, as they are afraid of not being able to merge to the outer lane. This design makes it easier to use the inner lane to go left.

> I don't understand how the turbo roundabout is any different than a typical two-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 ...

* https://en.wikipedia.org/wiki/Roundabout#Turbo_roundabouts

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.

We have one of these close to where I live. The idea is that the inside lane automatically becomes the outside lane after half way around, and when you are on the outside lane you are automatically forced to exit soon after.

I think it just is a regular two-lane roundabout? We have one of these nearby me in Cleveland, it works pretty well.


This is a very elaborate version of the turbo roundabout, checking out streetview might help.


The inside lane changes into the outside lane. This is usually done by traffic analysis. Meaning: it doesn't always immediately change the inside lane into the outside one. It works quite well for roundabouts with heavy uneven traffic (close to an Ikea :-P).

Follow a lane around and you'll find that the inside lane becomes the outside and the outside lane exits.

It's a two lane roundabout with an integrated instruction manual that makes it much easier to use.

The lanes spiral outwards as they go round.

This style exists in the UK too: near where I group is https://maps.app.goo.gl/hjhi3gQijUGnuXha7 and a bunch of others like it: five roads in and out, with lanes that naturally flare out (though with the option to cut over right to continue further round). Quite intimidating when you're learning to drive.

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.

Having lights there defeats a lot of the roundabout. The turboroundabout definitely does not have traffic lights. Look at this[0] implementation, the one you linked qualifies as a "turboplein".

[0] https://www.google.com/maps/place/Energieweg,+Nijmegen/@51.8...

> Having lights there defeats a lot of the roundabout.

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.

* https://www.fhwa.dot.gov/publications/research/safety/00067/...

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.

That satellite view describes it perfectly. Especially how it is differentiated from a standard 2 lane roundabout.

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.

That's neat. How does it handle more than 4 junctions? The Magic Roundabout was devised as a means to efficiently handle the junction of 5 or more roads.

I tried searching for that, but couldn't find a very good example. I don't see why that wouldn't work, though: just split into more lanes before you enter the roundabout.

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.

> There's no possibility to keep going around until you figure out where you want to go.

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.

You're not allowed to change lane once you've entered this type of roundabout. In practice the lanes are separated by a curb. Of course you still can change lane at the points where traffic joins the roundabout, but it's a sharp 90 degree turn and you'll discover real soon that it's a mistake to try.

There's one of these on the junction of the A3 at New Malden. https://www.google.co.uk/maps/place/A3,+New+Malden,+UK/@51.3...

Here's one in Helsinki, Finland: https://goo.gl/maps/NoWE44KLKukEeq4d9

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.

There's one in Espoo, Finland (Suomenoja). It's apparently the "roundabout from hell", although I don't personally get it. https://www.hs.fi/kaupunki/espoo/art-2000005975273.html

I would consider myself good with following direction signs and being in traffic in general. However, I find that roundabout very confusing.

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 :)

The only "downside" with these is in case of an emergency vehicle entering the roundabout.

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.

Works just fine in the real examples of these roundabouts, this[0] is a better example which is widely implemented in the Netherlands. The bollard thingies are really small, but don't encourage driving over them. Emergency vehicles can go over just fine.

[0] https://www.google.com/maps/place/Energieweg,+Nijmegen/@51.8...

This[0] is a very elaborate version of the turbo roundabout, checking it out in streetview might help. But basically the roundabout functions more like a standard junction with room to choose a direction before turning (I don't think there is an English translation for "voorsorteren", or sort before...).

[0] https://www.google.com/maps/place/Energieweg,+Nijmegen/@51.8...

"presorted" "prefiltered" would be adequate translations, but sort is a bit of an odd word to use for traffic in English.

> A better solution for high traffic flow is the turbo roundabout

Q: Is such a construction grade-separated and/or are the separate flows in controlled by traffic lights? The diagram isn't that clear...

I try adding it to the language list for turbo roundabout, but Wikipedia doesn't allow that. Different languages organising their content in a different way hurts the ability to make these kind of cross-language links.

The problem with The Netherlands is that in some cities (I'm looking at you, Nijmegen) they've built massive roundabout which aren't actually roundabouts.

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..

> A better solution for high traffic flow is the turbo roundabout[0]

See also sub-section in the main EN page:

* https://en.wikipedia.org/wiki/Roundabout#Turbo_roundabouts

there's one channeled roundabout here, it might be great for residents but if you happen to be channeled in the wrong lane it's a 3km detour before you can get back where you wanted to go.

Another potential problem is that it's not always possible to make a U-turn at a roundabout like this. Sometimes you can, but not always.

I don't like it. From the bottom, if you want to go straight you enter on the right lane. From the right, if you want to go straight you enter on the left lane. This lack of symmetry means you need to be very familiar with the path in advance, and not get confused about which orientation you're in. For the signage to be far enough from the roundabout to get your bearings in time, it will be too far for most people to even be looking for it. This design will add to the late merge asshole problem.

Late merges are optimal, and the fact that so many people disagree with this practice (or take it as a personal affront) is one of several gross failures of US driver education programs.

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.

> late merge asshole problem.

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

There's a difference between late merges and late lane changes, which is what OP meant. When all vehicles are merging into one lane, sure, the zipper merge is superior. But when you realise you're in the wrong lane right before an intersection and try to force your way over, that's the problem.

> There's a difference between late merges and late lane changes

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.

Correct. I mis-spoke. I guess I picked up on 'late merge' term from someone else and that's how I call it. But indeed I meant a last-minute lane change.

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.

We don't have many, and the few we do are pretty new, but several of the roundabouts near me in the US work like this.

Might be wrong, but I remember this existing (albeit with traffic lights) in the 90s near Amsterdam Amstel Station.

I expect most are better given that "In 2009 it was voted the fourth scariest junction in Britain."

Looks like it works with 4 roads, how about 5 like this one?

I first drove this back in the early 90s when I happened to be near Swindon (for some training), and a friend (who often worked in the area) had told me about it, so I deliberately went to it. Bear in mind this is pre-common-internet use era, so everything was hearsay and so on...

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...

I think it's because it's locally simple. At each decision point the rules are no different to normal roads and it's easy. It may look complex globally, but yeah then don't try to do that.

I wouldn't be surprised if it is safe partially because people think it's a nightmare to navigate

That's pretty much what the Wikipedia article claims, the roundabout has an "excellent safety record, since traffic moves too slowly to do serious damage in the event of a collision"

I used to drive over it occasionally. It was always decorated with broken glass from a collision.

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.

I've lived within a mile of the 'magic roundabout' for about 10 years. I traverse it frequently. I have never seen a collision or broken glass on it.

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)

Yes, that's implied by the linked article. Everyone's so terrified of it, they drive it at a crawl.

Not true. I am resident in Swindon and I don't know anyone who is 'terrified' of the magic roundabout. On the whole, we rather like it.

Caveat: I am talking about driving around it in a car. I wouldn't want to cycle around it when it is busy.

> 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. In 2010, the National Cooperative Highway Research Program concluded that the roundabout reduces injurious crashes by three quarters.

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).

The problem, as always, is that parties disagree on what "best" means.

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.

True, but in this case (apparently) there is the added wrinkle that this roundabout has better throughput than other designs, so what’s the downside? I guess it forces people to think harder than they’d normally have to while driving?

I definitely find myself taking slightly longer routes that let me avoid stressful situations, e.g. turning left onto a busy road.

I think characterizing "Vision Zero" as "safety at any cost" neatly illustrates what I'm saying about the local politics of traffic.

(It is an explicit component of Vision Zero that improved safety should not be expensive to communities.)

If they really want to reach zero the only answer is a combination of self-driving cars (remove the idiot monkey) and proper pedestrian management to have dedicated crossings, away from the automated intersections.

I lived in Swindon for 2 years and while drivers can find different things challenging, I would venture to say that it's a lot more straightforward when you're on it than you might imagine. It separates traffic effectively at peak times according to which roads they enter/leave, and as many have mentioned it slows cars down so you aren't pressured to make snap decisions either if you aren't sure. If all else fails, you can follow the car in front of you and if you picked the correct lane at first entry the chances are you will be led to the correct exit point.

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.

I grew up in Swindon and took my driving test there. The only complication usually is drivers who don't know ho to use it / are timid.

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.

For a real nightmare roundabout, the winner has to be Place Charles de Gaulle around the Arc de Triumph in Paris[0].

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.

[0] https://www.google.com/maps/place/Arc+de+Triomphe/@48.873766...

You get the gist of it if you drop into streetview and move around. [0]

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.

[0] https://imgur.com/gYPWfv2

In my private vernacular, it was specifically visiting the Arc de Triomph that prompted me to coin the term "traffic tornado" and note other, invariably less turbulent ones that I find in life.

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.

I've never looked at the Google Maps image of the Arc de Triumph before so a question immediately comes to mind upon looking at it. How the hell did all of those tourists/pedestrians get there? There doesn't appear to be parking on the inside of the circle, nor any apparent crosswalks at that 12 lane circular nightmare. Is there a tunnel hidden underneath you can go through? There's no apparent exit unless it is inside of the monument. Is there a shuttlebus that just straight up blocks the inner lane when it shows up?

There's a tunnel. I was there with my dad in 1993, and we only discovered the tunnel after we crossed the 8 lanes to get to the monument.

That's not even the best "Magic Roundabout", the one in my town is much better! https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempst...

I'm Canadian. We had a work trip to the UK. My manager kept saying "I think I can handle driving in there, how bad could it be?". I told him we'd die.

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."

Statistically, you are less likely to die compared to driving in Canada. UK roads may be confusing, but they are significantly safer than Canadian roads, as measured by fatalities per billion km driven.

(And Canada is already among the safest non-European countries, with significantly fewer fatalities compared to the USA)

This was years ago and I have actually now driven in the UK myself. Yes, I'm sure overall I'd be less likely to die if I were driving every day in the UK vs driving every day in Canada.

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)

As a Canadian, you should be proud that for almost 60 years you had a junction that was much worse, and possibly unique: the infamous Armdale Rotary, where traffic on the rotary and traffic joining the rotary alternated in priority.

* https://web.archive.org/web/20190816111546/https://en.wikipe...

That one at least has the normal sign, with the small roundabouts marked as black circles.

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.

Pah! I laugh at your pathetic 'magic roundabout', where the roundabouts don't even overlap.

Has yours had "Mad Mike" drift around it? ;) https://www.redbull.com/ie-en/videos/mad-mike-whiddett-drift...

There'd probably be a crash, it's never that empty.

Ahh yes, this roundabout where I managed to enrage a white van driver who then proceeded to tailgate right up the A1

Ha, I learned to drive around there in the late 90s, absolute nightmare.

But I'm pretty fearless these days!

Imagine coming from mainland europe and having to drive on the other side of the road (thus also taking roundabouts the other way round), and then navigating this baby...

The beauty of these kind of junctions is you can drive clockwise or anti-clockwise. Essentially it's not a roundabout but rather one junction comprised of lots of roundabouts.

The Colchester equivalent better demonstrates this: https://en.wikipedia.org/wiki/Magic_Roundabout_(Colchester)

Personal anecdote: I had to drive around one of these junctions during my driving test

In other Colchester roundabout news, the one at North Station is fun - it's a normal roundabout, but with a road cutting right through the middle of it too:


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.

I worked in Colchester around the time that was being built. It's much nicer now than what was there before (in my opinion). The only annoying thing about that junction is it can sometimes take a long time to traverse it because of all the lights.

The problem with Colchester is that it's plagued with heavy traffic and bad drivers.

Nuneaton has one such, at the junction of the A444 and A4254. Nottingham also has one, on the junction of the A52 and B6003.

The article explains why the Colchester one is particularly cursed: it's built on a native burial ground!

I strongly believe that the biggest reason people struggle with the Magic Roundabout is because it's called a roundabout, when it's actually just a collection of 5 roundabouts. If you tackle it one roundabout at a time it's actually not that bad at all, it could be much much better, but it's not bad.

I prefer magic roundabouts to the strange concoction which I've only ever seen in the Staines / Heathrow area; A roundabout with one road continuing straight through the roundabout. In order to run right you need to be left most lane approaching it. Turning right from the side road, it's ambiguous whether you are supposed to turn right onto the section of the main road going straight through or continue all the way around.

So it's a recursive roundabout?

Exactly, it's just a very small gyratory system.

By the time you reach Swindon, you've likely trained yourself well enough that it stopped being a problem.

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 worked a few months in Swindon (before mapping apps) and out-of-towners on business visits always got directions that went thru the Magic Roundabout. Not to worry, tho: they got hair-raising stories to tell.

Quick story time!

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.

Having the controls and seating position reversed also helps a lot in driving on the other side of the road compared to what you're 'used to' in my experience.

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.

I guess what this shows is two things:

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.

RE: #2

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.

Another example of this is the downtown area of a small PA town I stopped in recently. They had recently re-paved the entire center street with brick and stone. The sidewalks were wide and there were no curbs, only rubber-covered metal posts marking the boundary between car and pedestrian areas. As a driver, I found this design scary, because it was hard to visually see where I should be driving. But I noticed that the natural result of this was that I drove around 15mph despite signs coming into the town saying 25mph as the speed limit. Another cause of this is that the sound of bricks under your tires gives the impression that you're going faster than you actually are. It was scary, but it put my focus as a driver on not hitting pedestrians, poles, or other cars, rather than slavishly following lines and curbs. Not hitting pedestrians, poles, and other cars is the entire point of the lines and curbs, so it's a more direct way to solve the problem.

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.

This is actually a fairly common redesign that one can find in several countries around the world over the past decade or so.

> Within Saskatchewan, east of Regina ...

Is it possible to get (Google?) Maps links for these?

Hi there, sorry about my delayed reply, I don't typically check comment replies on HackerNews. Doesn't look like Google's satellite has updated photos but here's some links:

The Diverging Diamond: https://www.google.com/maps/@50.4476864,-104.4361408,553m/da...

The Double-Roundabout: https://www.google.com/maps/@50.4769267,-104.2845914,552m/da...

The standard design: https://www.google.com/maps/@50.4471693,-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

Aren't those ideas the underlying premise of shared streets (woonerfs)? Basically remove as many signs, markings and kerbs as possible so there's no segregation, and usually break up vision lines. The driver uncertainty stops traffic being the dominant user.

Result lower accidents, much lower speeds, and above all safer cyclists, pedestrians and any kids playing.

Also far lower throughput, leading to severe daily congestion.

Which is presumably why they are never used for major through routes, so don't cause severe daily congestion. Though I would like to see far more streets, even some with appreciable traffic, converted to downrank cars.

Now imagine when "a police officer was stationed at each mini roundabout"!

I think that enforcing traffic law is one of the best ways to use police to keep the public safe. However, I suspect that having 5 cops at one intersection is a mis-allocation of resources. It would make that intersection safer, but at a pretty high salary cost, and even if the salary was available, it's likely at least some of the cops would be more useful at other intersections.

I grew up near a city called Birmingham in the UK which has it's share of... disturbing junctions:



They look insane on a map, they must have been hellish to navigate before GPS.

If you look at the See Also in the article, you will find 3 other roundabouts of the same name also in the UK, so it seems the country in general has some interesting traffic structures.

"Spaghetti Junction" was not. Just get in the correct lane, as signposted, and stay in it. It's actually easy to navigate. It may have resembled spaghetti to a headline writer in the 1960s, but it is not in fact a difficult junction.

The only junctions that terrify me are some innocuous looking ones on the A9 in the Highlands (a notoriously dangerous road at the best of times) - they are perfectly OK without much traffic but are a nightmare if it is busy.

Spaghetti junction is still hellish...

It looks like a fairly routine Japanese highway junction though.

The traffic engineer who managed to convince authorities that this was the solution to their problems must've been very charismatic.

They look scarier than they are in practice. What I hate more is those massive roundabouts with traffic lights on where dual carriageways meet. On those things you still have a mix of cars who don't know where they're going and lanes to be away of, but in addition you have traffic lights and cars moving at much higher speeds than on magic roundabouts.

Barcelona. It's fine to have a roundabout where several roads meet, each with multiple lanes, and the circle itself to have 6 or more lanes [1]

[1] As an example https://www.google.com/maps/@41.3748215,2.1491456,232m/data=...

That does look a busy junction but I was thinking more like when motorways cross.


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.

I've resigned myself to a massive detour to avoid one of those beasts. After a few incidents that were a bit scary and a few where I just went round it three times trying to figure out when to change lanes I just gave up and found a different route.

Something of a roundabout afficionado it seems [0] ... also ex British Airforce, which given the odd way that the brits assign status, could provide alternative explanations for this madness beyond charisma .... he hadn't even 10 years experience as a working civil engineer when he came up with this.

[0] https://en.wikipedia.org/wiki/Frank_Blackmore

Wow. I googled him a little more, and his story was fascinating.;

> 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.


It was the 1960s. There was a huge push for all sorts of High Modernist experimental (re)design of British towns. Ring roads, tower blocks, roundabout-only layouts like Milton Keynes, brutalist public buildings, all that kind of thing. The country is slowly recovering from this.

> The country is slowly recovering from this.

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 bought a DEC MicroVAX on ebay a few years ago and the seller lived in Swindon. I passed through the Magic Roundabout on the way there and the way back (during rush hour). Having never encountered anything like it before it was... Well, I'd love to tell you a horror story, but to be honest it was all very logical and flowed very well.

My favourite part of the entry is that it lead me to the discovery of the UK Roundabout Appreciation Society. Never change Britain.


Someone gave me the book "Roundabouts of Great Britain"[1].

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.

[1] https://books.google.dk/books/about/Roundabouts_of_Great_Bri...

I recently cycled some of the south coast of China. Some small towns there had roundabouts which served to slow traffic down but had a different pattern than westerners are used to. They drive on the right, but people who want to turn left would do so immediately, keeping the centre island on their right side. People turning right or going straight would use the roundabout the same as westerners.

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.

Chicago has those as well. I believe you're supposed to go all the way around the central circle when making a left turn, but nobody does.

My favorite roundabout ever is a large traditional one with only two entrances/exits. Reminds me of a lot of codebases I've encountered.

Little detail, I love that they actually call it the Magic Roundabout in eg the traffic signs. I mean, it's a children's TV reference. Super nice, not everything official must be boring and dull.

When I was visiting the UK, I ended up driving through this intersection a couple of times. It wasn't really a big deal, even for someone not used to roundabouts or driving on the left.

Right - people tell me they find roundabouts really confusing but I say: imagine a one way street, and you're joining it at a T-junction. If you're in the UK the one-way street is going left. If you're in Europe or America it's going right. That's literally all a roundabout is. You can forget about the fact that it's circular. There's no extra rules I believe.

The joining roads in America would probably have "STOP" signs, whereas in Europe it will just be "Give Way"/"Yield", which makes the whole thing run a lot faster.

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.

What about the fact it has two lanes?

How's is it different to any other road with two lanes?

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.

On a roundabout there's usually not enough time to consider turning off as two separate maneuvers. Instead you follow certain rules and it "just works".

i.e. join on the outside lane if you're turning off immediately and join the inside lane otherwise.

My driving instructor sketched The Magic on paper and asked me to draw various routes before he let me drive on it. My driving test went over it, so at least I was prepared!

with overhead video...


Metrics at work:

>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.

Indeed! This is a great example of why it's important to actually measure the things you care about, and not use a proxy or your gut feeling. If you just go by perception, the slower-moving traffic might fool you into thinking the roundabout has less throughput.

I live close to this magnificent piece of engineering, AMA.

It’s not easy to understand why it is structured this way. As a local do you have any idea why it’s composed of five mini roundabouts instead of just a single one? Does it feel like it handles high levels of traffic better?

You can travel both directions around the roundabout this way, if you need to get to the exit that's to the right of yours, you can do it, whilst a traditional roundabout would require you to go all of the way around, which would improve congestion I think.

I'm not sure on the actual design decision reasonings, however you can reach many of the exit junctions with multiple routes. So if everyone drove around it sensibly, there _would_ be fewer cars stuck in traffic.

I'd have to see a study or simulation. I can't take it on faith, because what I see is very many points where cars have to stop and yield. Multiple routes could just imply packing more cars into one ginormous intersection where they block each other trying to get in or out. And where you have multiple routes to one junction, you have merging.

Thanks ! I’m curious to know your viewpoint ! Do you notice more accidents than on standard junctions ? Is it really that confusing for newbies ?

I enjoy it! you can avoid lots of traffic and queuing if you take a different route around the whole roundabout.

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.

> Do you notice more accidents than on standard junctions ?

I think the whole point of the design is that there are fewer accidents at the same time as higher throughput.

Does it have one of those "X days without an incident" signs next to it? :)

Great idea. Will pitch that to the council.

Ah, a fellow Swindonian!

He's not the only one.

My Canadian province has been on a big roundabout building spree. Nothing fancy just one lane or two lane types. I like them but many people fear them for some reason I suspect because they don't understand them. Some people actually go the wrong way when entering (against traffic). Some people will cross from an outside lane over the inner lane nearly crashing into cars.

Brit from Ontario here and have to agree. The problem is roundabouts were never on the Canadian drivers test until a few years ago and no one knows the rules.

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.

If you live or learned to drive somewhere that doesn't have them I can understand being confused or scared by it. I love them but frequently see people stop in the middle of one because they think they need to yield to those entering

This was the default rule in Russia until very recently. Most (but not all) of roundabouts had yield signs on each entrance essentially enforcing “normal” rule, still it’s an utter source of confusion as many larger roundabouts have complex priority signs and lights systems, so it couldn’t go into muscle memory.

Hanger Lane Gyratory System - the most frightening roundabout in the UK (or possibly anywhere) - https://www.mylondon.news/news/west-london-news/ealings-noto...

Having commuted through it every day for 2.5 years, I’m genuinely not sure what the fuss is about. It’s just a big roundabout. (And while this isn’t a pure positive!) if you were unsure, it was usually so slow moving you had plenty of time to figure out what to do.

The only disturbing aspect it brought to my life wasn’t navigation stress, but rather its unpredictable effect on my commute. :)

> if you were unsure, it was usually so slow moving you had plenty of time to figure out what to do.

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.

If this was voted the 4th scariest intersection where the first 3?

NVM: Found the answer in the wiki. http://news.bbc.co.uk/2/hi/uk_news/england/london/7140892.st...

In usual fashion, Wikipedia links sources where they can. In this case, this is the source: http://news.bbc.co.uk/2/hi/uk_news/scotland/glasgow_and_west...

There's one just like this North of Hatton Cross Station (just outside the perimeter road of Heathrow Airport) ...


These are actually pretty easy to drive around: just think of it as a tiny ring road with round-abouts along it.

The only difference between this and a "normal" ring road with round-abouts is that the distance between roundabouts is 50m not 5km :)

A sign of globalization: there are now many roundabouts in Montana. I get the impression that every new road construction project, where there is space, uses roundabouts. Many drivers still don't understand how to use them however.

The linked page didn't explain how it worked well, but this Wired video does: https://www.youtube.com/watch?v=6OGvj7GZSIo

The closest thing to this I've seen in America is a 5 points intersection, which most of just have a sign that says "keep right" or something to that effect. Might as well just say "Good Luck!"

Columbus Circle in NYC, on the corner of the park [1]

[1] https://en.wikipedia.org/wiki/Columbus_Circle

Phsaw, how about a 7 point intersection:


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.

I build maps for a living. This roundabout complex has been a test case for map building systems for at least the last fifteen years. It's positively brutal in its special cases.

Never change, you brilliant British bastards.

This roundabout still gives me shudders after learning to drive (well trying to learn to drive) in Swindon in the 90s.

I find the whole "inner ring for people who know what they're doing and outer ring for people who have no business driving in heavy traffic" concept highly attractive but the fact that the safety claims revolve around injuries and makes no mention of overall accidents (if it reduced overall accidents surely they would mention it) makes me suspect this thing is a fender bender (and therefore traffic jam) factory.

From tfa:

> In 2010, the National Cooperative Highway Research Program concluded that the roundabout reduces injurious crashes by three quarters

>From tfa:

> 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?

I wonder how people with a terrible sense of direction (like me) handle this roundabout. Seems like a nightmare.

A valuable thing to remember about roundabouts is that they are generally meant to slow down traffic in areas of high pedestrian activity and are, above all else, a safety mechanism.

There are roundabouts in places with no pedestrians at all.

I never implied there weren’t.

I'd crash so hard ...

I've navigated this thing a few times. The first time I just stayed on it for 20 minutes, trying to work it out, and yeah .. basically just confused as hell for a while.

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 ..

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