The Beauty of Roundabouts
gruhn.me
gruhn.me
- 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 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.
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.
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.
- 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 fact that you mention light-controlled roundabouts highlights that they do not, actually, "work perfectly fine".
Roundabouts are a practical example of the tyranny of the majority; minor traffic flows suffer against major. The centre of Salisbury is a perfect example, constantly gridlocked at two roundabouts except at odd hours on a Sunday.
Adding traffic lights to 'fix' this problem then leads to tailbacks on the major routes and congestion on the roundabout, such that the timing sequence for the minor routes are subsequently reduced, returning to the original problem.
Roundabouts, in the plurality, are used as a lazy 'solution' to at-grade traffic crossing, which the road designers themselves presumably don't have to suffer. They also cause pollution from brake dust from slowing and exhaust fumes from accelerating.
I don't think anyone is claiming that roundabouts work in every and all situations: design handbooks often say they're good 'up to X vehicles per hour/day'.[1] But that does not mean they do not work, or not useful, for <X.
Intersections are an engineering problem, and there is a hardly ever an engineering solution that works everywhere and always. There is usually a spectrum of solutions for the various situations that are faced.
[1] https://www.fhwa.dot.gov/publications/research/safety/00067/... § 1.6.1, 3.3.1
The council and national highways are working on it, but the problem is not one of roundabouts - its one of increases in traffic and lack of capability to make the roads bigger and/or build a bypass. Unless we're willing to knock down a load of housing and cultural sites we're stuck with something around or slightly more than the road capacity we have.
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.
Still, all across the world the average driver seems to below what I imagined the average driver to be, before I started driving myself.
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.
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.
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".
Some data seems to conflict with this:
> A 1993 study in the Netherlands examined collision experience at 181 intersections converted to roundabouts. Pedestrian collisions (all injury severities) dropped 73% and pedestrian casualties dropped 89%.
> Evaluations in Sweden concluded that single-lane roundabouts are very safe for pedestrians, at about a 78% reduction in injuries, and that multi-lane roundabouts are about as safe as other intersections.
> A 2002 study of collision experience at the roundabouts in Park City, Vail, West Vail and Avon, Colorado, showed 2 pedestrian crashes prior to the roundabouts operating with over 164 million vehicle movements, compared to 1 pedestrian crash with roundabouts experiencing over 282 million vehicle movements.
* https://www.tac-atc.ca/wp-content/uploads/weber.pdf
> With the installation of a roundabout, this study finds that the before-after analysis results in a 40% decrease in all severity injury crashes for all roadway users, a 70% decrease in fatal and serious injury crashes for bikes and pedestrians, and a 15% decrease in total pedestrian bike and pedestrian crashes.
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.
* 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!
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.
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.
A good trade
- 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).
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.
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.
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.
Junctions have their own problems though: Usually drivers will not permit a cyclist to merge in front of them while traffic is not stopped, which means if the stream of traffic is continuous you need to plan your lane change when traffic is stopped by lights.
As a pedestrian, roundabouts with islands (aka all roundabouts here) are vastly superior.
You know that's like, the entire point of roundabouts: force traffic to slow down.
I'm not convinced of this either. It may make sense when considering one intersection in isolation, but over a corridor with ten intersections, you are going to get caught in a red light at least once, and that one full stop will cost you more than all the gains you get from not having to slow 10 mph through each intersection.
This is setting aside fuel efficiency and safety considerations which also favor roundabouts, IMO.
But collisions overall are down, and severe crashes down 80%:
* https://tirf.ca/blog/fact-vs-fiction-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.
While it would slightly defeat the purpose in some ways, roundabouts with traffic lights are a thing:
* https://www.traindrivinginstructor.co.uk/roundabouts-with-tr...
So if one way has heavier traffic (at times), things could be signalized to allow (e.g.) that one direction primarily some of the time and the other three directions the rest.
> Finally, they're also (mostly) worse for cyclists and pedestrians.
Some data seems to conflict with this:
> A 1993 study in the Netherlands examined collision experience at 181 intersections converted to roundabouts. Pedestrian collisions (all injury severities) dropped 73% and pedestrian casualties dropped 89%.
> Evaluations in Sweden concluded that single-lane roundabouts are very safe for pedestrians, at about a 78% reduction in injuries, and that multi-lane roundabouts are about as safe as other intersections.
> A 2002 study of collision experience at the roundabouts in Park City, Vail, West Vail and Avon, Colorado, showed 2 pedestrian crashes prior to the roundabouts operating with over 164 million vehicle movements, compared to 1 pedestrian crash with roundabouts experiencing over 282 million vehicle movements.
* https://www.tac-atc.ca/wp-content/uploads/weber.pdf
> With the installation of a roundabout, this study finds that the before-after analysis results in a 40% decrease in all severity injury crashes for all roadway users, a 70% decrease in fatal and serious injury crashes for bikes and pedestrians, and a 15% decrease in total pedestrian bike and pedestrian crashes.
another con: If only one of the exits gets backed up, it clogs the traffic circle and causes every connecting road to back up.
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.
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.
The "you need power to accelerate out of danger" is a motorcycle argument (and a pretty flimsy one); in a car, you are not gas-pedaling your way out of anything. Your emergency control devices are brakes and steering, that's it. There are moves that powerful acceleration lets you get away with, and they are all reckless, and often built on the assumption that only you have that acceleration. People are now using their high-torque EVs like this. You will never be in a collision close call caused by someone or something doing something unexpected, where the reaction of stepping on the accelerator is the action that saved the day. Can't deny that it could help run from a tsunami wave or fire or something.
You can draw a circle on the road and have “roundabout rules” without the need for any car to even turn their wheels.
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.
Drivers treat them as a normal roundabout by giving way to traffic on the right.
I mostly like them though.
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.
For example, the one at [0] regularly sees bendy buses[1] traverse it without any issues. The trick is that there's an outer ring of asphalt and an inner layer of paving stones: cars the asphalt as it is far more comfortable to drive, but longer vehicles like buses and trucks can let their rear wheels ride over the raised paved area as well.
And yes, it works the same when they are completely round instead of oval - this just happened to be the first clear example I came across.
[0]: https://www.google.com/maps/@52.0660752,5.1198197,3a,75y,21....
[1]: https://busposities.nl/voertuig/cxx_SolarisUrbino18E_9686
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.
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.
Of course, they are augmented by allowing the main direction of travel to bypass the circle and go over/under it
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 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.
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.
Make the roundabout larger then, and you can keep just about the same speed. How can a roundabout take more mental and physical capabilities and slow you down less, than a stoplight on the interstate? That's very backwards, and not sure what roundabouts you've experienced, if that's the case.
But to answer your question, roundabouts always require drivers approaching from all directions to slow down, lookout for cross traffic and assess other drivers' behavior. Stop lights have 2 modes that promise safe passage, and they can be set to prioritize routes.
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.
And the second thing is when you have very large roundabouts, there’s always a bit of chaos involved between shifting lanes from the innermost lane towards the outermost lane because I’ve noticed people don’t enter the roundabout on the right lane, so there’s always a little bit of chaos during the crossover.
I have literally never noticed this. Are you perhaps speeding through them, instead of properly slowing down?
> there’s always a bit of chaos involved between shifting lanes from the innermost lane towards the outermost lane because I’ve noticed people don’t enter the roundabout on the right lane, so there’s always a little bit of chaos during the crossover.
Multi-lane roundabouts are a completely different beast, and shouldn't be used until both the engineers and the population have gotten plenty of experience with regular one-lane roundabouts. Two-lane ones are just about doable with hard lane separation, but anything more is asking for trouble.
All the sources I can find say roundabouts reduce crashes of all types.
Carmel, IN, America's "roundabout capital" has more than tripled in population while reducing overall traffic accidents / year: https://eri.iu.edu/erit/case-studies/carmel-indiana-roundabo....
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.
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.
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.
Especially with heavy traffic, the traffic all slows down, a lot, from the section before the roundabout. Everyone is always in a hurry, so likely 10-25 MPH over the recommended speed (not the speed limit) for the roundabout, and all of them are at a 6 foot following distance.
You are playing with death to step into that. It's no joke. You end up effectively waiting for the upstream light to turn red so traffic can clear and you can cross.
The only solution I've thought of is to put a large grocery cart full of paint buckets at the roundabout for pedestrians to push into the crosswalk without risking their own lives.
In the real world, drivers frequently do not stop in the presence of pedestrians.
I mean, it depends on your standards for roundabout. We didn't put highways through town centres so largely highway ramps and pedestrians are mutually exclusive scenarios here. Where pedestrian crossings exist, there's usually (a) an island and (b) 2 lanes prior to the island, splitting to 4 lanes either where the traffic is already slowed or past the island, which makes it much more pleasant than crossing at an equivalent junction. Also as a driver, it means you've cleared the pedestrian area before you have to consider/deal with the cross direction drivers as there's a small waiting area post-pedestrian-crossing/pre-roundabout.
If you're stuck because you already have a highway in your urban core and need pedestrians to safely cross the highway, then you are pretty much limited to overpasses and underpasses.
- When there's a low traffic lane merging with a high traffic one, it's either impossible to enter, and you have to wait forever, or there's a traffic light cleverly hidden a couple hundred meters away, as to not break the illusion
- They do work in the middle of nowhere merging two low traffic roads. However for every roundabout you have to slow down which breaks the flow of traffic, and consumes more gas. There's often a string of 5-6 of these things.
- Having to turn to even go straight makes me queasy. Not too bad if there's just 1, but can be super uncomfortable when there's a string of them (which is common)
- 2 lane roundabouts are crazy dangerous and confusing (which is the same). You might understand how they work, but the car behind you might not. Besides due to the geometry of the whole thing, you have to cut across diagonally to car traffic to get to the inner lane.
- There's another kind of 2 lane roundabout, which is less dangerous, but only allows you to turn right from the outer lane. If you're unfamiliar with which kind you're facing, you might be in for a detour. Even if you know, there's often a fight to merge into the inner lane, which is not exactly pleasant or safe.
I guess roundabouts are a niche solution that can work sometimes, but there's a whole internet cult for them, composed mostly of people who don't really live in an area with roundabouts.
Alternatively: it's people who do live in areas which have a lot of them - and well-designed ones at that. Most of your issues boil down to "people aren't familiar with them", which automatically solves itself over time.
There is no such thing as a "roundabout fever", just like there isn't a "traffic light fever". To any halfway-competent engineer, they are just one tool among many.
They have their downsides, but "It doesn't work in America" is more informative of American motorists than roundabouts
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.
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.
Damage to roads is related to the third power of speed and the fourth power of axle weight.
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.
Is there something unique about American drivers or traffic engineers which makes them incapable of handling the concept of a roundabout that I am unfamiliar with?
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.
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.
>How big was this roundabout when it took 25 minutes doing 3 victory laps in a roundabout?
This is explained in the next sentence, I took two wrong exits and had to double back?
It was clogged probably :)
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.
[0]: https://nl.wikipedia.org/wiki/Turborotonde#/media/Bestand:Tu...
https://www.youtube.com/watch?v=wqF8zLWo570
Even refueled while driving and got pulled over by police once. The police was basically just like "It's not illegal, but we got a report about you and wanted to make sure you're okay. You can keep doing it as long as you're not impeding traffic".
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.
Thun has just a really good street system and city layout generally I guess.
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'.
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.
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.
And to make it a two-for-one special: roads shouldn't need speed signs to begin with. The road should be designed for a certain speed, so that driving any faster feels uncomfortable and unsafe. If it is physically possible to drive 80 in a 30, something has gone terribly wrong already. Roundabouts are a great addition to this: you can't exactly speed through them, so you are forced to slow down.
I’d rather be in flow state while doing any of those, than constantly be yanked out of it because I’m concerned I might be do 3kph over the legal speed limit.
Well, provided you can still stop in time should the lights begin to change.
Also I'm not riding 'blindly', though if I can oversee that from afar, and it's empty, I'm pretending color-blindness.
I'm doing this since about 1980 at speeds up to 70kph for maybe up to two minutes on flat grounds
(exception 73.5 uphill here https://www.openstreetmap.org/?mlat=50.719937&mlon=7.111630#... in the middle of two lanes between gridlocked cars, unforgettable ooomph),
55 to 60 for about an hour, and 45 to 50 effortless, with no sweat, almost any time. Of course I feel strong head-winds, and they do slow me down.
And never ever caused an accident, just touched the rubberlip of a Citroen 2CVs rear bumper with my front wheel once at about 65.
In a roundabout ofc, because the fuckers slowed down for turning out without even blinking. Bicycle was trash, but I've been unhurt, except for very numb and tingling at the same time, hands, soles of my feet, and initial breathlessness. Which all went away after a few minutes, no bruises, no torn clothes.
After having made a salto over the handlebar, managed to separate from my bicycle in the air, pushing it aside, and landing flat on my back after 15 to 20 meters, or so.
Holding my head upright, intentionally. No tingling or numbness there.
https://www.openstreetmap.org/#map=19/51.070329/6.999691
Long live the CWU-36P Nomex Flight Jacket from about 1981. Still have that one, but with a new zipper, and new cuffs. I'm considering that thing my 'supercape' :-) And real Levis 501 as they were made in 1988!
Got myself a 'pre-owned' Bianchi with Campagnolo group the next day, for 1500 Deutsche Mark and cackled madly with joy :-)
80 to 90 downhill(on paved roads, not through the wilderness!), if weather allows, and I'm in top form. 90kph is not a good, or easy thing on any bicycle. But... speed is what I need!
Where am I even doing 90? Several places on CO82, on my way back from Independence Pass to Aspen. If weather (mostly wind, can't have strong gusts!) and traffic permits.
https://www.openstreetmap.org/?mlat=39.1197&mlon=-106.5797#m...
What else? I don't wear a helmet. And no doping. Never even tried that. For what?
His house, built into the volcanic rock, was beautiful too: https://en.wikipedia.org/wiki/C%C3%A9sar_Manrique#/media/Fil...
Or a dog: <https://en.wikipedia.org/w/index.php?title=Roundabout_dog&ol...>
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]
Land can approximately be converted to a recurring cost via rents.
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.
I assume the person who designed that was 6 months away from retiring to Florida.
What a legacy. I’m having a vicarious chuck now.
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.
It’s not, I used to live near Perth, Tasmania.
How many Perths are there?
https://lostcolonials.wordpress.com/2015/09/20/milton-keynes...
Fun for drifting late at night. Like a chav version of tōge from Initial D.
Lights suck unless there’s sufficient traffic.
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.
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.
This is basically it.
Roundabouts make sense for low/moderate traffic, but you get to a point where the traffic gets so heavy that a roundabout just clogs things up, especially when traffic is primarily coming from one direction.
I will die on one hill though: 4-way Stop intersections should absolutely never exist, and any situation where you think a 4-way Stop is appropriate should be replaced with a roundabout.
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.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.
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.
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.
But mostly I see roundabouts as one of the most depressing, ugly and environmentally-destructive gimmicks of 20th century car culture.
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.
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.
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.
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.
"Traffic" here is an analogy for "society at large", so any response along the lines of "but the government built the roads" or "but public transport is more efficient" is kind of missing the point. And it's a good analogy in that it shows how much order can emerge from people acting in their self interest without being aware of other peoples plans or goals. I also think it makes it pretty intuitive that predictable and general rules of the game are far superior to ad hoc and ever changing ones, although as an argument in favor of laissez faire, it's definitely not a good one.
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.
https://www.youtube.com/watch?v=pBtrEZpa6OQ&pp=ygUQcm9uZGVsb...
Yes, roundabouts are good, but there's things to consider.
In the highway code see rule 190 for two threeway roundabouts stuck together. https://highwaycode.org.uk/roundabouts/
Wikipedia shows a few e.g.
https://commons.wikimedia.org/wiki/File:Germany,_Sachsen-Anh...
https://commons.wikimedia.org/wiki/File:Waterloo,_Ontario,_m...
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
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.
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.
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An important note: in the U.S., the vast majority of jurisdictions permit making a right turn on a red light, and some, including the state of Oregon, permit making a left turn onto a one way road from a red light. In high congestion areas, such as here in Las Vegas Valley, many drivers will not fill a right lane at a red light when they are not turning right as a courtesy to those needing to turn right at the intersection.
During commute hours, everyone disobeys all laws to get home or get to work. When there are regularly spaced roundabouts on a long stretch of road, drivers get exceptionally impatient and will drive at the performance limits of the vehicles, late-braking like they are F1 drivers. This ends up grouping all of the drivers into a very solid wolf pack who will not stop for anyone and will speed through the roundabout, making it impossible for pedestrians and drivers other onramps to enter the roundabout.
The vast majority of drivers do not know how to use the roundabout, as is evidenced when they enter from the left lane of a two-lane road and use the exit lane that is only marked for use from the right lane. Americans who know how to use the roundabout respond to this by habitually stopping at the roundabout entrance when they see a car in any lane entering the roundabout at high speed, which is most vehicles. Then the drivers behind the stopped vehicle think the stopped vehicle is driven by someone who doesn't know how to drive on a roundabout and begin honking incessantly or attempting to illegally pass the stopped driver.
Henderson, Nevada provides many such examples of this. Most interesting to me is that parts of the town have nearly identical roads that are served by either only traffic signals or only roundabouts. My experience is that the roads with traffic signals have far fewer issues than the roads with roundabouts.