63 points ngruhn 2 days ago 131 comments
herbst 2 days ago | parent
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.
LargoLasskhyfv 1 day ago | parent
However, crossings with traffic lights I can take at any speed I'm able to, when they are green for me, and I don't need to turn. Or if I can oversee them from afar, and they are empty, and I can give a shit about 'lights'.
herbst 1 day ago | parent
Other than that it's obviously by design. There is no reason to speed at constant 50kph in a city. Nether for a car, motorbike or e-bike.
rightnutwingjob 9 hours ago | parent
Which does two things, raises state revenue and causes drivers to spend way to much time concentrating on how fast they are going rather than driving to suit the conditions and paying focusing to what’s going on in front of them.
And don’t get me started on the pot holes.
oneeyedpigeon 50 minutes ago | parent
Well, provided you can still stop in time should the lights begin to change.
marcosdumay 7 hours ago | parent
The one that where mass transit works better.
But yeah, a city still needs cars, and roundabouts are still unbeatable in low-traffic crossings. But they are not the most impacting change a city can make.
brudgers 1 day ago | parent
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]
rightnutwingjob 9 hours ago | parent
Here’s one in Australia near Perth:
https://youtu.be/h8lhX9Q6Z5g?si=eloUWLcH8q3eJiZH
And I’m certain I’ve driven through other roundabouts with traffic lights in other states.
perilunar 8 hours ago | parent
They work well when the peak-hour traffic tends to block some of the entrances. You can use the lights to allow the blocked entrances to flow, then turn the lights off out of peak-hour.
Jarmsy 7 hours ago | parent
throwawayffffas 21 minutes ago | parent
wat10000 8 hours ago | parent
teddyh 9 hours ago | parent
Or a dog: <https://en.wikipedia.org/w/index.php?title=Roundabout_dog&ol...>
magarnicle 7 hours ago | parent
gs17 7 hours ago | parent
orthoxerox 3 hours ago | parent
grebc 9 hours ago | parent
Lights suck unless there’s sufficient traffic.
UltraSane 8 hours ago | parent
projektfu 8 hours ago | parent
In my current city, I can identify at least 3 intersections that would be better as a roundabout, but I don't have my hopes up.
grebc 7 hours ago | parent
Also where I moved from recently, they changed a roundabout intersection into a traffic lights intersection. And the traffic used to flow. Now it’s a stand still.
There’s always so many little insights when you use the road daily that a planner will never have unless they do the same.
Melbourne where I am kind of close to now, has an absolute clusterf*ck of overpasses, underpasses, toll ways, free ways, tunnels all coming & going out of a neatly planned grid. They probably think it’s planning perfection while driving it as a non-resident is an absolute nightmare. Sydney which is famously poo poo’d for not being planned in Australia is 10x more straight forward to drive.
pornel 9 hours ago | parent
orev 8 hours ago | parent
derbOac 8 hours ago | parent
I think roundabouts work fantastically well in some places but in others they are unnecessary and in others don't work as well as alternatives. Maybe that's obvious but every so often I feel like they are overapplied — probably because of what you're mentioning, along with the fact they were underapplied in other areas in the past. I've come to like them usually but sometimes it feels like the civil engineers were having too much fun at the cost of practicality.
UltraSane 8 hours ago | parent
pkamb 2 hours ago | parent
rusty_rick 9 hours ago | parent
ngruhn 26 minutes ago | parent
erelong 8 hours ago | parent
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
mig39 8 hours ago | parent
A similar collision on a roundabout is almost always a "glancing" blow, at an angle, and rarely causes injury or death.
Roundabouts force you to slow down when approaching. Stop signs can be ignored. Roundabouts can't.
lexicality 1 hour ago | parent
esafak 8 hours ago | parent
pocketman 8 hours ago | parent
jkubicek 8 hours ago | parent
Bimos 8 hours ago | parent
propter_hoc 8 hours ago | parent
- 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.
emil-lp 7 hours ago | parent
Freedom2 6 hours ago | parent
xethos 5 hours ago | parent
They have their downsides, but "It doesn't work in America" is more informative of American motorists than roundabouts
TacticalCoder 2 hours ago | parent
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.
embedding-shape 49 minutes ago | parent
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.
ds_opseeker 1 hour ago | parent
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.
forgotmypw17 6 hours ago | parent
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.
sandos 3 hours ago | parent
embedding-shape 48 minutes ago | parent
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.
piker 2 hours ago | parent
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.
VBprogrammer 2 hours ago | parent
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.
piker 2 hours ago | parent
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.
embedding-shape 52 minutes ago | parent
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.
cjs_ac 2 hours ago | parent
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.
piker 2 hours ago | parent
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.
derr1 1 hour ago | parent
cjs_ac 1 hour ago | parent
windward 1 hour ago | parent
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.
embedding-shape 1 hour ago | parent
Still, all across the world the average driver seems to below what I imagined the average driver to be, before I started driving myself.
cjs_ac 1 hour ago | parent
oneeyedpigeon 56 minutes ago | parent
GlacierFox 43 minutes ago | parent
RHSeeger 41 minutes ago | parent
throwawayffffas 28 minutes ago | parent
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.
cjs_ac 5 minutes ago | parent
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.
throwawayffffas 31 minutes ago | parent
jmkd 58 minutes ago | parent
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.
darkwater 33 minutes ago | parent
pkamb 2 hours ago | parent
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".
kazinator 2 hours ago | parent
tokai 1 hour ago | parent
bulder 1 hour ago | parent
pasc1878 6 minutes ago | parent
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.
embedding-shape 1 hour ago | parent
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.
ubercore 35 minutes ago | parent
* 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!
cucumber3732842 22 minutes ago | parent
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.
embedding-shape 11 minutes ago | parent
dagurp 2 hours ago | parent
kazinator 2 hours ago | parent
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.
kawsper 2 hours ago | parent
embedding-shape 57 minutes ago | parent
oneeyedpigeon 51 minutes ago | parent
rob74 2 hours ago | parent
- 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).
embedding-shape 58 minutes ago | parent
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.
kazinator 2 hours ago | parent
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.
williamdclt 30 minutes ago | parent
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.
MrSkelter 2 hours ago | parent
You can draw a circle on the road and have “roundabout rules” without the need for any car to even turn their wheels.
Lvl999Noob 1 hour ago | parent
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.
scrlk 52 minutes ago | parent
Drivers treat them as a normal roundabout by giving way to traffic on the right.
embedding-shape 53 minutes ago | parent
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.
Gravityloss 1 hour ago | parent
embedding-shape 55 minutes ago | parent
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.
jwr 1 hour ago | parent
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.
zeumo 1 hour ago | parent
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.
cucumber3732842 13 minutes ago | parent
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.
ncruces 1 hour ago | parent
You know that's like, the entire point of roundabouts: force traffic to slow down.
hahajk 1 hour ago | parent
another con: If only one of the exits gets backed up, it clogs the traffic circle and causes every connecting road to back up.
bgnn 1 hour ago | parent
ubercore 37 minutes ago | parent
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.
outside1234 31 minutes ago | parent
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.
tremon 15 minutes ago | parent
cucumber3732842 27 minutes ago | parent
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.
YuechenLi 7 hours ago | parent
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.
kazinator 2 hours ago | parent
Bimos 7 hours ago | parent
gorgoiler 6 hours ago | parent
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 6 hours ago | parent
https://lostcolonials.wordpress.com/2015/09/20/milton-keynes...
Fun for drifting late at night. Like a chav version of tōge from Initial D.
ngruhn 2 hours ago | parent
kj4211cash 6 hours ago | parent
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.
pkamb 2 hours ago | parent
ds_opseeker 1 hour ago | parent
Love this.
Likewise "free markets" which work great when embedded in a system of laws and regulations. Or more critically, in a high-trust system where people keep their word because that's what matters.
But not sure how many people are in favor of the more unregulated black markets, where contracts are enforced by rule of violence instead of rule of law.
As if we've forgotten Hobbes, and the horrors he lived through which informed his philosophy.
Quiza12 4 hours ago | parent
pi-err 2 hours ago | parent
But mostly I see roundabouts as one of the most depressing, ugly and environmentally-destructive gimmicks of 20th century car culture.
M95D 1 hour ago | parent
I expect it to be a lot worse.
- roundabout, light traffic : break, turn, accelerate again, 100% of the time
- (dumb) traffic light, light traffic: 50% chance of stopping and accelerating again, 50% chance of not slowing down at all.
- roundabout, heavy traffic : stop, move 3m, stop again, move 3m more, stop again, repeat 10 times, finally turn, accelerate.
- traffic light, heavy traffic: stop & engine off, start & move 100m, stop & engine off, start again and accelerate.embedding-shape 1 hour ago | parent
I'll take a roundabout any time of the day, but then I mostly to drive out in the public when the traffic is the least, so any stop lights tend to be more annoying that useful.
Miksel12 26 minutes ago | parent
throwawayffffas 24 minutes ago | parent
Their conclusion i believe was they were about the same in pretty much all regards.
It was highly synthetic, people driving around a small course with roundabouts or fourway intersections, continuously for an hour or something.
chris_money202 1 hour ago | parent
AndrewSwift 1 hour ago | parent
In France, if you move up too far, you can no longer see what color the light is — consequently everyone waits back where they should.
In the US, you can edge out into the traffic and still see your light.
embedding-shape 1 hour ago | parent
Not sure this will stop people. In Spain we have the same, the stop lights go before the pedestrian zebra thing, yet still some people think you're supposed to stop on top of the zebras, beyond the stoplight, then they wait for someone behind them to blink. No, makes no sense to me either.
INTPenis 57 minutes ago | parent