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.
show comments
herbst
The city I grew up in had no roundabouts back then. Today it does have some, some were even made and removed again since. People there hate roundabouts.
The city I live nearby now has so many roundabouts that I can drive for over an hour without seeing a traffic light. It always had those, people are used to using them.
Guess what works better and barely has any traffic issues at all.
show comments
rusty_rick
This led me down somewhat of a rabbit hole looking at roundabouts, then to the official roundabout page from the Department of Transportation, where I couldn't believe my eyes to see that National Roundabout Week is next week: https://highways.dot.gov/safety/intersection-safety/nrw
show comments
brudgers
[edit: for clarity, I am not against roundabouts]
I don't have real expertise in civil engineering
Traffic lights have a smaller physical footprint and require less construction activity.
Traffic lights fit on a cost spectrum from two stop sighs, to four stop signs, to stop signs plus blinking lights, to non-trivial signaling.
First make it work. Then make it good. Then make it fast.
Engineering is not a one size fits all discipline.
[edit: I have a background in urban planning, architecture, and real-estate development]
show comments
teddyh
> Roundabouts come with this otherwise unused patch of land in the middle. Apparently, it has become common practice around the world to put some random art there, or a little green space, or a fountain, or a "welcome to this town" sign.
Maybe, living in France where maybe half the roundabouts of the world exist, I have been exposed to too much beauty.
But mostly I see roundabouts as one of the most depressing, ugly and environmentally-destructive gimmicks of 20th century car culture.
grebc
I like roundabouts over lights at small intersections. I still prefer simple give way/stop that changes the next intersection over roundabouts.
Lights suck unless there’s sufficient traffic.
show comments
pornel
This dreaming about roundabouts is as American as the fantasies about using metric one day.
show comments
YuechenLi
The key disadvantage of a roundabout is that it takes up more space and is harder to setup than plopping down a couple of stop signs.
They are awesome otherwise, I do like them better for low traffic intersections though because I don't have to stop and think about if the next car is going to yield or not.
show comments
pocketman
Roundabouts are superior to other intersection types in nearly every case. Two lane roundabouts are a notable exception.
Roundabouts are the Segway of civil engineering. In theory, a game changing transport innovation. In practice, just a little too mismatched with everyday aesthetics to properly fit in. Dorky and annoying for pedestrians too!
Good old traffic lights have a much better feature of being able to control traffic to allow for pedestrians, give cyclists a head start, give smaller side roads a look in at busy junctions, and giving a platform for traffic monitoring.
qingcharles
I feel like the author would appreciate Milton Keynes, which is an entire city of 180 roundabouts on a grid system:
Fun for drifting late at night. Like a chav version of tōge from Initial D.
show comments
Bimos
I think here in China we are not super fan of roundabouts. But we got a 4-lane roundabout with traffic lights [1] and a roundabout on elevated roads with traffic lights. [2]
I was in Aruba recently, and I discovered that they had entirely replaced their traffic lights with roundabouts. Easier to maintain and more efficient in the island's low-traffic regime.
Bimos
I was hoping that it was "404 not found"
kj4211cash
It's so funny seeing most of the comments, plus the original article, implying that roundabouts are always better or always worse than traffic signals. As someone who used to be a Transportation Engineering professor, they have a time and place where they outperform traffic signals but it's definitely not everywhere. It is known and there are many traffic simulation software tools that will give you a pretty good indication of what will happen if you put a roundabout here or a traffic signal there.
This thread reminds me of when my libertarian friend was explaining to me how traffic shows how everything can work well when everyone acts in their own self interest. Well, sure, except for all the traffic laws, the difference between User and System Optimal that traffic engineers spend much of their lives trying to bridge, and, you know, the fact that it took an enormous effort by government to build smooth roads and put up signs everywhere. Sigh. I'm not saying Transportation Engineering is the most important, innovative field, but funny things happen when not transportation engineers talk about transportation systems.
show comments
somat
Reminder that technically a 4-way stop is the smallest possible roundabout.
show comments
elisbce
It is so funny to read this because in reality, roundabouts are some of the worst traffic congestion makers :)
show comments
erelong
I think I prefer maybe the simplicity of 4 way (or even 2 way) stops
There are some funny intersection videos from idk what country that have no stop signs or lights or roundabouts and somehow lots of people still manage to get through them
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.
The city I grew up in had no roundabouts back then. Today it does have some, some were even made and removed again since. People there hate roundabouts.
The city I live nearby now has so many roundabouts that I can drive for over an hour without seeing a traffic light. It always had those, people are used to using them.
Guess what works better and barely has any traffic issues at all.
This led me down somewhat of a rabbit hole looking at roundabouts, then to the official roundabout page from the Department of Transportation, where I couldn't believe my eyes to see that National Roundabout Week is next week: https://highways.dot.gov/safety/intersection-safety/nrw
[edit: for clarity, I am not against roundabouts]
I don't have real expertise in civil engineering
Traffic lights have a smaller physical footprint and require less construction activity.
Traffic lights fit on a cost spectrum from two stop sighs, to four stop signs, to stop signs plus blinking lights, to non-trivial signaling.
First make it work. Then make it good. Then make it fast.
Engineering is not a one size fits all discipline.
[edit: I have a background in urban planning, architecture, and real-estate development]
> Roundabouts come with this otherwise unused patch of land in the middle. Apparently, it has become common practice around the world to put some random art there, or a little green space, or a fountain, or a "welcome to this town" sign.
Or a dog: <https://en.wikipedia.org/w/index.php?title=Roundabout_dog&ol...>
Maybe, living in France where maybe half the roundabouts of the world exist, I have been exposed to too much beauty.
But mostly I see roundabouts as one of the most depressing, ugly and environmentally-destructive gimmicks of 20th century car culture.
I like roundabouts over lights at small intersections. I still prefer simple give way/stop that changes the next intersection over roundabouts.
Lights suck unless there’s sufficient traffic.
This dreaming about roundabouts is as American as the fantasies about using metric one day.
The key disadvantage of a roundabout is that it takes up more space and is harder to setup than plopping down a couple of stop signs.
They are awesome otherwise, I do like them better for low traffic intersections though because I don't have to stop and think about if the next car is going to yield or not.
Roundabouts are superior to other intersection types in nearly every case. Two lane roundabouts are a notable exception.
One additional benefit (or at least an unproven, theoretical benefit): https://www.youtube.com/watch?v=qdbJJ8UhM1I
Roundabouts are the Segway of civil engineering. In theory, a game changing transport innovation. In practice, just a little too mismatched with everyday aesthetics to properly fit in. Dorky and annoying for pedestrians too!
Good old traffic lights have a much better feature of being able to control traffic to allow for pedestrians, give cyclists a head start, give smaller side roads a look in at busy junctions, and giving a platform for traffic monitoring.
I feel like the author would appreciate Milton Keynes, which is an entire city of 180 roundabouts on a grid system:
https://lostcolonials.wordpress.com/2015/09/20/milton-keynes...
Fun for drifting late at night. Like a chav version of tōge from Initial D.
I think here in China we are not super fan of roundabouts. But we got a 4-lane roundabout with traffic lights [1] and a roundabout on elevated roads with traffic lights. [2]
[1] https://maps.app.goo.gl/rY6AH8nUEKvRuk1LA
[2] https://maps.app.goo.gl/Wea6Wt5FwHgKmG4C9
I was in Aruba recently, and I discovered that they had entirely replaced their traffic lights with roundabouts. Easier to maintain and more efficient in the island's low-traffic regime.
I was hoping that it was "404 not found"
It's so funny seeing most of the comments, plus the original article, implying that roundabouts are always better or always worse than traffic signals. As someone who used to be a Transportation Engineering professor, they have a time and place where they outperform traffic signals but it's definitely not everywhere. It is known and there are many traffic simulation software tools that will give you a pretty good indication of what will happen if you put a roundabout here or a traffic signal there.
This thread reminds me of when my libertarian friend was explaining to me how traffic shows how everything can work well when everyone acts in their own self interest. Well, sure, except for all the traffic laws, the difference between User and System Optimal that traffic engineers spend much of their lives trying to bridge, and, you know, the fact that it took an enormous effort by government to build smooth roads and put up signs everywhere. Sigh. I'm not saying Transportation Engineering is the most important, innovative field, but funny things happen when not transportation engineers talk about transportation systems.
Reminder that technically a 4-way stop is the smallest possible roundabout.
It is so funny to read this because in reality, roundabouts are some of the worst traffic congestion makers :)
I think I prefer maybe the simplicity of 4 way (or even 2 way) stops
There are some funny intersection videos from idk what country that have no stop signs or lights or roundabouts and somehow lots of people still manage to get through them