My best friend is a highly experienced civil engineer, specialized in designing intersections. His take on roundabouts:
- They are adored by urban planners because they look nice and you can put a statue or fountain in the middle
- They reduce T-bone collisions
However:
- Small fender benders and sideswipes are much more frequent
- They use way more area
- They work where each direction has an approximately equal amount of traffic. However, usually, one direction (north/south, say) has a larger share of the traffic. In those cases, the bulk of traffic all needs to slow down, downshift, turn a bit in one direction and then turn a bit in the other direction for the minority of traffic that's bleeding on or off the main artery. In those cases, a traffic light is better because the timing can be adjusted to the proportion of traffic from each direction (and more flexible since it can be adjusted over time).
- Finally, they're also (mostly) worse for cyclists and pedestrians.
Essentially, they have use cases, especially in small towns, and they're pretty, but they're usually not the right engineering solution.
I live in the UK, which has roundabouts, mini roundabouts, double and triple roundabouts, traffic-light controlled roundabouts, and magic roundabouts. They work perfectly fine.
The difference is that traffic flows very differently in the UK to the US. In fact, the way traffic flows in those two countries captures a lot of their cultural differences. In the US, everything needs a grand overarching theory and imposed order, which is why Americans need traffic lights, and why they’re so keen on a very specific set of liberties that allow them to freely live such similar lifestyles. The UK embraces mild chaos and ruthless pragmatism, with everyone finding locally optimal solutions to their own problems, so things like roundabouts fit well with the national mindset.
Try Spanish roundabouts. On the whole, poorly designed, implemented and regulated. On roundabouts with two or more lanes, laws favour those on the outside lane, so everyone takes the outside lane even if they are travelling 3/4 of the way round. As a result drivers who are in a position to take an exit, do not take that exit. In addition, indicators are not used by most drivers, or they simply leave their indicators on all the way round. In addition, it is not allowed to exit a roundabout from the inside lane even on to a two lane exit. In addition many roundabouts have three lanes to enter onto a two lane roundabout, or two into one, etc. No one knows the rules, or follows them, and no one seems to care, from the civil engineers right down to the end users. The only winners are repair shops.
In comparison, UK roundabouts are civilised examples of harmonious intellectual etiquette. Enjoy them.
[source] I learned to drive in Swindon, home of the Magic Roundabout.
If you complain about Spain, then go live and drive in Italy :)
I agree with this, and I'll offer a rationale.
Because the US largely "grew up with cars", the economy was built around the expectation that folks can drive to work. The population density of the US reflects this, and mass transit just doesn't work in small/middle America. That means everyone needs to be able to drive. If you can't drive, you can't work. That isn't the case in the UK, and you'll notice a lot of these "driver beware" analysis is explained by the fact that driving in the UK is seen as a privilege whereas it is a right in the US. This sort of "mild chaos" is prohibitive for a lot of would-be UK drivers, and they just take the bus.
>They work perfectly fine.
I don't want to celebrate UK roads too much. The majority of roundabout users in the UK are not indicating properly. Too many people are stopping at them when they have priority. Lanes are just a suggestion and using the correct lane is an invitation for someone to drive into the left of you.
In other areas: enough people don't know how to use a slip road that it becomes a problem to those who do. Likewise the flashing ambers of a pelican crossing. Lane discipline is much worse than on the continent, to the point you can see it creating traffic jams. Lots of people are driving big cars without the confidence needed to remain in their own lane.
There are millions of drivers who've never passed a theory test. We could do with more ruthlessness.
I feel like you're singling out UK drivers without much evidence here, I've driven lots across continental Europe, although mostly Spain<>France<>Germany<>Nordics, but in all countries people tend to not indicate properly, inside of roundabouts or outside of them. I'll admit to people in the Nordics being slightly better at signaling, but they make up by being so scared and non-confident in their driving that their hesitation causes near-accidents, rather than the opposite.
Still, all across the world the average driver seems to below what I imagined the average driver to be, before I started driving myself.
All of that is user error. The roads themselves might be in disrepair, but are otherwise well-designed.
It may be user error, but that doesn't mean roundabouts aren't a footgun. It only takes one driver who doesn't do everything correctly to cause problems. It's not much fun driving around in the correct lane, only for someone to pull alongside you to the left (equivalent of "right" in the US, of course!). I failed a driving test because someone cut across me on a roundabout.
"I failed a driving test because someone cut across me on a roundabout." That driver may have cut across you on that roundabout but that doesn't mean roundabouts are a footgun.
When comparing two interfaces and one allows a larger amount of user error that interface is inferior.
The point is roundabouts require more work to navigate correctly than a four way intersection with traffic lights. Thus drivers are more likely to navigate incorrectly.
> When comparing two interfaces and one allows a larger amount of user error that interface is inferior.
Seeing a safety issue and ignoring all other considerations is an excellent example of the ‘overarching theory and imposed order’ I argued that Britain rejects in my first comment.
If a given tool tends to have a high amount of user error, odds are there's a problem with the tool
Not gonna lie, I know about the flashing ambers of the pelican crossing, but they are uncommon enough, whenever I see one, I spend several seconds wondering what is happening, until it clicks it's one of these crossings.
American, in an area getting more roundabouts. The two most heartfelt criticisms of roundabouts I've heard are:
- I have to pay attention every time I go through one. (Vs. having your mind elsewhere works fine with traffic lights? That might explain some of those T-bone crashes.)
- Certain multi-roundabout intersections are "because the Road Dept. hates us" horrors to drive through. Most-often cited - https://www.google.com/maps/@42.5058488,-83.758072,18z?entry...
From my PoV, roundabouts are generally a good thing. Mostly because local engineering standards for traffic lights are wretchedly low - so I can get where I'm going far faster through roundabouts.
The UK has an over-reliance on roundabouts for junctions with motorways and large roads. They are also missing out on Turbo roundabouts, which are super cool and very common in the Netherlands.
The UK’s spiral roundabouts are the same as Dutch turbo roundabouts.
> the bulk of traffic all needs to slow down, downshift, turn a bit in one direction and then turn a bit in the other direction for the minority of traffic that's bleeding on or off the main artery.
Slowing/calming traffic like this is a good thing. Make it impossible to speed. Enforce the existing 35mph speed limit via concrete rather than allowing cars to rip through a yellow light at 70mph. You're also ignoring this aspect when you call roundabouts "(mostly) worse for cyclists and pedestrians".
A place where traffic slows down, without actually stopping, and becomes congested with no time/space gaps between vehicles, is worse for pedestrians.
> becomes congested with no time/space gaps between vehicles, is worse for pedestrians
Why? This feels like it's assuming pedestrians share the street with vehicles, but besides the US and some other places, don't most "modern" countries have separate pavements/streets for pedestrians? Besides in the country-side, vehicles and pedestrians don't generally share the road in populated areas here in Spain. For crossing roads outside cities, building a pedestrian tunnel below or a bridge above seems to preferred here, except in the cases where it isn't possible, and in cities obviously.
In my city in Norway, at least, there is never a traffic pattern where it's not either:
* a small roundabout with really clear pedestrian right of way marked * a pedestrian path that takes you over or under the road instead of crossing it
It's great!
> Why? This feels like it's assuming pedestrians share the street with vehicles, but besides the US and some other places, don't most "modern" countries have separate pavements/streets for pedestrians?
Surely this is a joke or just a flimsy pretext to imply that murka bad or whatever.
Even with a fully paved and sidewalked roundabout (or intersection of any other type) the more of a clusterfuck it is the less time and attention any given traffic participant has to give any other traffic participant is and this is where you get all the stupid "idiots trying to pass each other in a hallway" type misunderstandings and whatnot. It's just better for everyone if things aren't a clusterfuck.
Right, you're talking about "traffic participant", are you including pedestrians or not? Because as I said, in many places, "vehicles" and "pedestrians" are well-separated and don't impact/affect each other, so not sure what cluster-fuck could be created there. Seems less of a cluster-fuck than relying on cross-walks and stop-lights?
>Right, you're talking about "traffic participant", are you including pedestrians or not?
Yes, the point of inclusive nonspecific language is in fact to be inclusive and non-specific.
>Because as I said, in many places, "vehicles" and "pedestrians" are well-separated and don't impact/affect each other, so not sure what cluster-fuck could be created there. Seems less of a cluster-fuck than relying on cross-walks and stop-lights?
This is exactly the sort of garbage take the firste sentence of my comment was made to apply to. Even the richest places with the most investment in traffic segregation still have a lot of cross walks and signals.
The traffic has to yield to pedestrians when entering and exiting a roundabout, period.
Not in UK.
However there are often pedestrian crossings across the roads or the volume is low enough pedestrians can easily cross. A local roundabout got busy enough we had crossing added less than 10 years ago and the biggest road there was a minor B road.
I am a pedestrian due to sight issues and have found very few places where it is difficult to cross when needed.
No it isn't unless all driver all break the law and don't stop for waiting pedestrians.
That's a thing that happens.
But then, how come you blame this on the existence of roundabouts and not on the lawlessness of drivers?
> Small fender benders and sideswipes are much more frequent
Do you have any data on this? Everything I've ever read about them points to exactly the opposite conclusion. They actually reduce accidents and by a significant margin.
My only guess would be that you are referring to the US, where people are not used to roundabouts and yielding without a STOP sign.
> they're also (mostly) worse for cyclists and pedestrians
For cyclists, this is mostly true IMO (depending on implementation), but for pedestrians roudabouts are way better than traffic lights. In the absence of lights, pedestrians have right of way on crossing, so no waiting time, and physically slowed traffic make it safer.
>but for pedestrians roudabouts are way better than traffic lights.
This is ignorant texbook thinking.
As a pedestrian it's far easier to safely time a light, even one without a cross signal, than it is to cross through the un-broken streams of traffic that are entering/exiting a roundabout. You basically have to cross a ways back from the roundabout where the traffic is more like "just crossing a normal road". Which sucks if it's 4-lanes or really busy or fast or there's no sidewalk provision for that (like in the case of roundabouts at highway ramps) and is just a lot more walking to begin with.
For roundabouts that wouldn't be deserving of a light (i.e. the ones replacing 2/4way stops) it's a lateral move.
Depends on the driving culture and familiarity with roundabouts for sure. Moved from the US to a city in Norway with almost exclusively roundabouts, and it's _so much nicer_. Even in the edge cases, I have never once found myself wanting a traffic light.
Simple intersections can have very small roundabouts, and bigger ones you can connect roads from so many weird directions and have traffic flow well that I would never want to return some of the intersections I experienced in the US.
> In those cases, the bulk of traffic all needs to slow down, downshift, …
You know that's like, the entire point of roundabouts: force traffic to slow down.
Roundabouts do not need more space.
You can draw a circle on the road and have “roundabout rules” without the need for any car to even turn their wheels.
Not a civil engineer but as far as I know, the space is part of the point. If you keep the roads straight but just draw a circle in the middle, you don't have a roundabout. It only works properly if the drivers have to curve in and out of it.
You could keep the same space I guess by pinching the roads tighter near the entries/exits but I don't think anyone is talking about that.
The UK has mini roundabouts, which are just a painted white circle on the road: https://upload.wikimedia.org/wikipedia/commons/b/b0/Mini-rou...
Drivers treat them as a normal roundabout by giving way to traffic on the right.
> You can draw a circle on the road and have “roundabout rules” without the need for any car to even turn their wheels.
If it's physically possible to "skip the roundabout", if it's just a drawing rather than hard barriers, people here (Spain) will just skip it straight up, unless there is a ton of traffic. I think lots of these driving rules and infrastructure has to take local culture into account, as it differs from "We follow laws like our collective lives depend on it" to "We see laws more like suggestions" depending on the country.
There are more positives. - They keep traffic flowing better so you won't get "platoons" of cars all moving and stopping at the same time. This is especially effective when you do this in a sequence of intersections. - They calm do down traffic by forcing cars to slow down. - You don't need to install and maintain traffic lights.
Platoons of cars with space in between allow for pedestrians and vehicles to cross the road, downstream.
Nothing worse to have upstream of where you are trying to enter a road, or cross it, than a busy four way stop, with cars coming out of it at regular intervals, without sufficient time/space in between.
As a bicyclist and pedestrian (in Denmark) what is it that’s worse about roundabouts for me? I think they work really well.
I think to an American, a roundabout is this thing that only works for cars and don't take pedestrians or bicyclists into account, with no paths or crosswalks or anything, so hence "Worse for pedestrians". I don't blame them, both roundabouts and care for pedestrians seems uncommon over there, so of course their experience will point towards roundabouts being worse overall.
(UK experience) If you're trying to cross the road leading onto one, it's much harder to tell if a vehicle is going to hit you at speed. I often observe people turning quickly, without indicating, and had I chosen to cross at that time, there would have been some kind of accident. Junctions tend to not have this problem since cars turning out of them are usually going much slower.
Another pro: they can easily support more than 4 connections
another con: If only one of the exits gets backed up, it clogs the traffic circle and causes every connecting road to back up.
I think that's overly negative. Roundabouts have their place, mostly for low traffic intersections, but I agree that they tend to be overused, also here in Europe. Two examples where roundabouts are not the right solution:
- when there is too much traffic: if there is a constant stream of cars in the roundabout so you have to wait for a long time before being able to enter it, or force your way in (risking a fender bender), that's
- when you actually want traffic to flow. My small city has built a bypass road which is however IMHO completely botched: it starts with a roundabout, and the first exit leads to the route going through the center, only the second one goes to the bypass, so people are more likely to drive through the town. And it has three more roundabouts along the route, further making the option unattractive (in addition to a relatively low speed limit of 60 km/h and several tight curves).
> - when there is too much traffic: if there is a constant stream of cars in the roundabout so you have to wait for a long time before being able to enter it, or force your way in (risking a fender bender), that's
I think it's fine with lots of traffic in a roundabout, but it has to be somewhat balanced.
For example, we have a roundabout that sits on a relatively popular road, with one exit/entry that leads to a bigger highway. During rush hour, there is heavy traffic, from from/to every one of the three points, so traffic naturally divides, as cars turn off.
However, when there is no rush hour, the highway exit/entry isn't used, so cars mostly just pass through the roundabout, and everything still works, as the two entries/exits are still balanced.
Issues would arise if it's only one entry/exit being used, as then it'd always block the two other entries from being used properly, but seems that never happens, so seems to me it's proper and works well, regardless of the traffic being heavy.
It would be interesting to know your (friend's) country of origin.
As someone who drives manual, and so actually having to downshift myself when necessary, I would rather negotiate a larger roundabout 100% of the time than having to stop at a red light 30% of the time.
On my current gearbox, I can dip to around 30 km/h and gently accelerate while staying in 4th gear, which I'd be in up to around 50 km/h. So if I hit an uncontended larger roundabout that takes me 50-30-50, I don't have to do anything, transmission-wise.
Manual driving culture is probably one reason roundabouts have been popular in Europe long before North America started to warm up to them.
I don't understand the argument? Seems like you're saying that not having to handle a gear change makes roundabouts better, but that applies to both your manual technique and automatic, so I don't see how Europe would be different from NA?
Also, I'm not a particularly frequent/experienced driver but 4th gear at 30kmh on a roundabout doesn't seem very safe, it does not leave you much control to react to something unexpected (some car coming up that you didn't see, a car who changed their mind last minute about exiting, a car changing lane poorly...). Being able to decelerate or accelerate quickly is pretty important on a roundabout. Not such a big deal on a very big roundabout with excellent visibility where there's no-one, but that's pretty rare in europe at least.
Roundabout cyclist and pedestrian safety is a solved problem, in the Netherlands of course.
In Sweden they have these huge roundabouts in the countryside. Very large diameter and gentle curves. You can maintain your speed. Awesome. Saves energy too. I assume there's a huge amount of tried and tested traffic innovation that could be directly just copied.
In Spain we have these two, sometimes right outside metropolitan areas, that see a lot of daily traffic, especially around rush hour. They're naturally balancers, if you plan them correctly, makes a ton of sense to default to roundabouts instead of stoplights.
Especially nice for us who plan our car trips based on when there will be the least public traffic out there, as roundabouts don't force you to stop when there is no traffic, and you can essentially keep the same speed with these large roundabouts.
> They work where each direction has an approximately equal amount of traffic. However, usually, one direction (north/south, say) has a larger share of the traffic. In those cases, the bulk of traffic all needs to slow down, downshift, turn a bit in one direction and then turn a bit in the other direction for the minority of traffic that's bleeding on or off the main artery. In those cases, a traffic light is better because the timing can be adjusted to the proportion of traffic from each direction (and more flexible since it can be adjusted over time).
This point is so under-appreciated. Roundabouts are really good in some cases, but they're over-utilized in England. Imagine if the US had roundabouts on the interstate and you're getting close.
I think the main problem in England is that there is just too much traffic for too little road. I don't think there is a simple infrastructure solution to that problem.
For example I was going to point out that roundabout completely fail when one direction becomes nose to tail congested but when I thought about local examples, I'd rather take that over a set of traffic lights where it becomes near impossible to get out from one direction if the traffic keeps backing up onto the junction.
> I think the main problem in England is that there is just too much traffic for too little road.
I think Jevons paradox basically guarantees this in both countries. The difference between the two countries (in my theory) is how much responsibility they're willing to place on the drivers. The UK requires much more driver effort for good reasons I suggest in another thread.
> Imagine if the US had roundabouts on the interstate and you're getting close.
What's the problem with a roundabout on the interstate? Obviously it'd have to be huge to account for the speed, so people don't need to change speed too much, but given the right size, it'd work wonderfully.
Nothing depending on your perspective. Mine is a U.S. perspective and a disposition against. They slow things down and require more mental and physical capabilities than the U.S. approach. That’s not accidental or because U.S. people are dumber, it’s just a cultural difference between the countries in terms of driver expectations. I’ve proposed a rationale elsewhere.
The replies to your comment would be a lot funnier if I didn't share a country with some of these people.
You're not gonna "driving culture" your way around a 10:1 volume difference and only a fool would act like you could.
And this is coming from someone who's a big fan of roundabouts (and 4-way stops) on the basis that bad drivers have a worse time at them.
That would generate stronger agreement if the bad drivers’ struggles mostly affected them. Instead, their chaos radiates outward significantly onto those who know how to drive.
The "use more area" needs to be considered in the sense that, designed properly, they eliminate left turn lanes and "suicide lanes" in the center of the road.
Instead, with proper design, you make this "left turn" by going to the next roundabout, going around to follow the road the opposite direction, and then make a right turn.
It's also only true when compared against a no-frills intersection. A two-lane roundabout has better overall throughput than a two-lane intersection with traffic lights. To increase throughput, they usually add turn lanes to avoid cars having to stop in the through lanes -- but the turn lanes require more road surface than the roundabout would have.
I live in the US and roundabouts simply don't work.
Not much of America's traffic infrastructure works well. Every month, combined with poorly trained motorists, it contributes to another 9/11's worth of fatalities. The infrastructure you think works, kills enough people for a thirteenth month at the end of every year.
They have their downsides, but "It doesn't work in America" is more informative of American motorists than roundabouts
Yeah I regularly drive in France which has terrible drivers (road deaths way above EU average in France) but it's nowhere near as bad as the US.
The one thing people should ponder is this: Germany has less than 3x the number of road deaths (no matter how you count it: per 100 K people, per kilometer, etc.) than the US. And yet every time I'm in Germany I happily drive at 125 mph on the highway (including when I drive to Poland, where most autobahns near Dresde have no speed limit at all whatsoever). And at 125 mph, I'll get overtaken by some cars going proper fast.
So, what, 65 to 70 mph max speed limit vs unlimited speed and three times the deaths: what's the problem?
Note that I'm certainly not advocating for US (or France for that matter) highways without speed limits: drivers are way too bad.
Germany is somewhat an exception when it comes to good and safe driving though, I think they're all afraid the government will take Autobahn away from them if they drive too bad.
It's a huge difference passing through France, having near hit collisions every hour on the highway with distracted French families, arriving to start passing through Germany, and suddenly people actually use their blinkers, drive on the right side, seemingly everyone knows defensive driving, and no one is up in your ass if you're at the speed limit.
Love driving in Germany though, countries should look into how they managed to get the car culture they have. Maybe it helps the Germans invented the automobile and all that comes with that. Probably still there is lessons to be learned from them.
Huh. You might want to look at how the residents of Carmel Indiana think about this.
https://www.carmel.in.gov/government/departments-services/en...
a city frequently ranked in the top 10 places in the US, also frequently ranked as one of the best cities in the US for cyclists.
Thank you so much for putting into words what I have feeling but struggling to verbalize. (Boston area, drive for work.)
There is one more downside, they are easy to get lost in, especially in an unfamiliar area. Apple Maps does an OK job guiding me most of the time, but just yesterday I spent an extra 25 minutes going through the same roundabout 3 times before I went the right direction, and each time I had to drive the wrong way, turn around, and then negotiate the same roundabout again.
> but just yesterday I spent an extra 25 minutes going through the same roundabout 3 times
How big was this roundabout when it took 25 minutes doing 3 victory laps in a roundabout?
You might want to petition your local government to put the signs of the exits before the roundabout, together with exit signs inside of the roundabout, helps a lot to see what exit you should take.
Alternatively, try a different map viewer, both Google Maps and Waze handles roundabouts excellently with zero issues, Apple Maps might still be too new to be useful for daily use.
Roundabouts are perfect when youre confused, just go around and read all the signs 3 times, then select the exit! :)