This is a problem with all multi-lane layouts and exacerbated by drivers' behaviour.
The problem is road users new to the road do not know which lane to be in already and they are pressured to go fast. The instant it looks like they've chosen a lane, a driver from behind who is familiar with the layout closes the gap in the other lane, trapping them.
This can be mitigated a bit by the first user having the confidence to slow down and straddle lanes until they are sure of the correct lane, but it's surprising how quickly such opportunities are missed.
The real problem is familiarity with lane layouts allows the road to operate at far higher capacity then normally possible and with less maintenance. They are squeezed to their limits in morning rush hours comprised of mostly familiar users. You'll even see users observing essentially invisible road markings because they're doing it from memory. No chance of you're unfamiliar with the road. Roads start to fail way before 100% capacity, but these lane markings allow that to be squeezed further during rush hours.
Coming out of Oxford on the A4144 there are two lanes; the left lane is for taking the first two turns and the right lane for the remaining three. But, drivers unfamiliar with the layout who haven't seen the markings, or who fancy jumping the queue, will sometimes use the left hand lane to go straight ahead onto the A44. There's a similar situation coming from the A40 to the East.
I've seen a few accidents there and even been involved in one as a result of this (someone tried to undertake me at speed as I exited, and caused a collision, 100% their fault according to our insurers).
Two lane roundabouts are pretty good. More than two lanes are very questionable. And roundabouts which include... stoplights!?!? are just stupid.
I live in the Netherlands, where roundabouts are very common. In many cases, they are an improvement.
But NL is also a huge bike country. And at most roundabouts, bikes have right of way. So as a car driver, you have to worry about other cars as well as bikes which may turn (go away from the roundabout) or continue (cross the adjacent road circularly around the roundabout.
In good visibility conditions, it's ok. And by OK, I mean it can still really f* up car traffic, especially when it is a high traffic area not far from a school. In lower vis conditions, and/or when electric higher speed bikes are concerned, it becomes a whole new kind of danger.
I would argue that the benefits of roundabouts diminish or fully disappear when the number of lanes exceeds 2, or when traffic lights are added to roundabouts, or (and!) especially when bike paths intersect with and circulate around the roundabouts.
Under light to medium loads, roundabouts are preferable to junctions with stop lights, as you rarely need to wait long to enter the roundabout. But under high loads, they can cause starvation when there are no breaks in traffic along the more major road, so traffic cannot enter from the side road. When that happens, you need to add traffic lights to allow traffic to enter from the side road. But the traffic lights can be set up to only operate at busy times, so then you get the best of both worlds. Traffic lights on a roundabout at quiet times - yes, that's just stupid.
> But NL is also a huge bike country. And at most roundabouts, bikes have right of way.
The fact that it's on a case-by-case basis an not actually a consistent traffic law is really awful. To add insult to injury, the only signage is usually a yield sign painted on the road that is invisible as soon as it's dark and the road is wet. And this is of course further combined with the absolute scandalous amount of cyclists who don't have lights at night and are dressed in fully dark clothes.
Roundabouts are already a traffic situation that require heightened attention as a driver, so in the interest of safety I believe crossing cyclists should yield to cars at the exit. It's too many things to worry about otherwise. But at the very least, make it the same everywhere so it's always absolutely clear to both drivers and cyclists who has the priority.
This is near where I live and it is indeed safe, mainly because everyone drives incredibly slowly and cautiously since the experience is scary as hell.
> because everyone drives incredibly slowly and cautiously since the experience is scary as hell
Apparently there are fewer accidents on the roads when the traffic lights aren’t working. The reason is exactly that - everyone is terrified and drives really slowly to make up for it.
Using roundabouts of roundabouts it's actually possible to build a 3 dimensional roundabout where traffic along the x, y and z axis can safely meet on the surface of a sphere.
I’ve always thought that the safety effect of the roundabouts - is not anything related to it’s traffic flow properties, but rather the fact that roundabouts are confusing and people slow down and proceed with caution.
We could accomplish the same with other forms of creative driver-hostile road construction and deliberately unproductive signage.
Australia does well, but not everywhere. We also had our few decades of automania, that saw our tram lines ripped up in the burbs, and sprawl reach outward with highways. I had to battle this old auto-topian design this week in order to take my car to a mechanic, ironically.
There is a train station about 500 meters behind the workshop, as the crow flies. I thought I would just drop my car off, walk to the train, head into the city.
It took 45 minutes of detours and a lot of sketchy sections to actually get to the train station. Lucky to have the suburban train for sure, but this particular old suburb had assumed everyone was in a car, and it simply hasn't put in the work to make it traversable to pedestrians. No sidewalks, lots of dead end roads and uneccessary fences. At one point I was staring at the station, with no way to get to it. Looong impermeable business parks etc. I just wasn't meant to be there by design.
It seems that a lot of American traffic engineering is about increasing automobile throughput at the expense of all other factors. Safety, expense, even how economically productive the street is in terms of supporting businesses and housing.
Here's an explainer on "conflict points" [1] which seems central to the argument. Most folks intuitions are correct that roundabouts eliminate cross-traffic (major conflicts), but they also reduce merge, diverge and weave conflicts (minor).
I like roundabouts but American drivers on average have no idea what to do with them, not even from a common sense perspective. To be fair, American drivers are vanishingly able to handle four way intersection, but I digress.
There are two roundabouts near me. The same two problems are rampant.
1. Failure to yield and yoloing into the circle at or nearly at full speed. One of the circles has a full stop sign, where some drivers seem to think that just because they stopped they are entitled to go next and the traffic already in the circle should and will stop to let them go, like a four way. The other doesn’t have stop sign, and I think people take the lack of one to mean they don’t have to yield or in any way pay attention because, hey, no stop sign. Admittedly, part of this is due to shitty design of the circles themselves.
2. Cars in the circle suddenly exiting without signaling, often veering across the outer lane of traffic. Part of this is driver’s education issue (I don’t think they taught us about roundabouts when I got my license several decades ago), part is the fact that in general people are allergic to signaling and have no awareness of other vehicles around them, as we have the same problem on highways.
Perhaps this is more of an awkward transitional period for their use in the States, but honestly I think the bigger problem is we on average have very poor roadmanship and inconsistent road design.
Stanford University has been installing roundabouts in recent years. But they put pedestrian cross walks across all the entrances and exits. So you find yourself driving around and come across a car fully stopped in the loop because some kid is crossing the exit on foot.
In the Netherlands we had a huge phase of replacing regular crossings with roundabouts, which I consider to be an improvement. Now, however this is followed by a re-engineering phase of many of these roundabouts. The 2-lane ones, where a driver needs to pre-select whether they want to go a quarter round (turn right in Netherlands) or select for straight-ahead and 3 quarters round. The lanes on these roundabouts are separated by a rather high ridge to avoid drivers changing their mind and change lanes. This probably done for safety, except that they feel more unsafe now, by introducing "choice stress" upon entry of the roundabout, especially if the road directions aren't very clear. To me it feels like over-engineering.
I’m from rural Ireland, and I always remember my first roundabout - I used go driving with my dad when learning, and as the weeks progressed I’d get closer and closer to Killarney which was the nearest town. Coming from our side the first thing you meet is a roundabout with 3 exits, one bringing you out the roads that bypass the town, one to the town centre, and one to a housing estate off the roundabout. As I joined the roundabout I met a woman driving against me on the roundabout taking a shortcut to her exit of the housing estate - frightened the shit outta 16 year old me, my dad was spooked too. I managed to make room enough for her to pass - she was oblivious. My dad actually knew her, lived there all her life, she must have driven that road 1000 times - how often was she taking that shortcut
I grew up in a town in Australia nicknamed "The City of Roundabouts". Essentially all intersections in the entire town are roundabouts, including two lane ones, etc. It's quite common to drive the entire length of town (~20 blocks) in reasonably heavy traffic without ever stopping. On a good day you do it in 2nd gear, the whole way. At night you can do it in 3rd gear, because it's exceptionally easy to see headlights of any car you need to yield to.
Four way stops do not exist (I've never seen one in all of Australia), and they are still the strangest concept for me living in Canada. They feel like a colossal waste of time and energy, and vastly worse than roundabouts.
The greatest thing about roundabouts is that they protect against the idiot that goes through an intersection at full speed. He does that either because he is passed out behind the wheel or because he did not notice a stop sign and thought he had the right of way, or maybe because he just does not care.
Well with a roundabout if you just go straight ahead you hit the center circle. Good roundabouts always have a slight hill and some kind of barrier (a tree or some kind of statue) in the center so that the guy that just goes straight through will hit something in the center and wont come out the other side and will thus be less likely to kill an innocent person.
Single lane roundabouts are usually a good idea if the cost justifies it. Double and more lane roundabouts probably should be avoided in the US; they include rather obscure rules as to which lane you are allowed to drive in at any moment and americans do not like to learn new rules.
As long as that center circle is high enough. I had a woman in a Toyota (Camry?) fly over one at about 45+mph and slam into me as I looped around it. Totaled her car, broke parts off my Explorer (repairable). Her son then tried to attack me with my bumper.
She kept insisting I turned in front of her (technically true, I was in a roundabout). She was arrested for drunk driving, and, later on, fined for all the flowers she damaged in the circle and the median she also ran over on her way into the intersection.
Good roundabouts always have a slight hill and some kind of barrier (a tree or some kind of statue) in the center
Interestingly enough, a new roundabout was installed in my neighborhood. We considered something pretty to look at in the middle, but the city said no way. "Emergency vehicles need to be able to go through the middle at full speed". Meanwhile, busses have zero issues negotiating the circle at normal driving speeds...
This kind of roundabout is used to join one large road to one or more small road (think two lanes going from 6-12 on the clock, with single lane road at 3 & 9)
In the UK, we don't normally have stop signs, as most junctions have clear rights of way (https://www.rac.co.uk/drive/advice/road-safety/uk-road-marki... see "Give way to traffic on major road") In suburban roads, roundabouts are often used instead of stop signs. It allows much freer flowing of traffic in both heavy and light traffic.
Just don't look up the magic roundabout, thats just fucking batshit, we only have one. The reason why they keep it is because there is literally nothing else interesting about the place.
Not necessarily. Some roundabouts have the center circle partially paved so that oversize loads can drive right through if needed. There are curbs, speed bumps and road pillars that make it obvious for normal traffic not to take the shortcut.
It also doesn't fully protect vehicles already inside the roundabout. My father got rear-ended once while inside a roundabout by a possibly distracted driver and the car was a near write-off.
The main advantage of roundabouts is traffic fluidity. When compared to intersections with stop signs or traffic lights, unless it is full you can often enter a roundabout without coming to a complete stop first.
They're perfect for crossings with low to middle traffic. No useless waiting time, good visiblity and no need for traffic lights.
For heavy traffic, though, they're useless as the car flow of one entry/exit can take over the roundabout and block all other entries.
Also, it seems hard to understand for many drivers that regulations regarding changing lanes don't change in a roundabout. So more than 3 lanes are not advisable in my opinion.
Inside cites, those traffic lights in intersections were usually also semaphores for pedestrian crosswalks. So when you replace the intersection with a roundabout, you usually keep the traffic lights for the crosswalks alone. At the speed a car exits a roundabout, a non-regulated crosswalk could be quite dangerous.
So if an intersection is (e.g.) four-way, and one particular entrance monopolizes things than it can be given red at times and the others green (and than one-green/three-reds).
See (e.g.) "Performance and Safety of Roundabouts with Traffic Signals" by Tracz and Chodura:
> The paper presents designs, advantages and some drawbacks of various layouts of roundabouts with traffic signals, used in urban arterials on crossings with large traffic volumes. The authors analyze signal settings with alternative phasing used at intersections that can provide the intersection capacity of about 6500 veh/h in 2x2 lanes arterials or even 8000 veh/h in 2x3 lanes arterials. Accident statistics for roundabouts with traffic signals in Krakow are also given and discussed. In addition, presented are practical examples of changes of signalized roundabouts geometry; reconstruction into a form of turbo- roundabout and its effects regarding traffic safety and good performance.
Roundabouts for high traffic areas are good. The problem is when they are overused in low traffic areas where they create obstacles to efficient continuous motion, increase pollution, and waste time.
PS: One place that doesn't do proper traffic design (or architecture): Texas. They insist on placing massive concrete dividers everywhere and have camouflaged by wear obstacles in the middle of paths that are injurious to bicyclists. It's nothing like the Netherlands where there aren't many random, dangerous surprises.
Personally, I'm fine with the simple single-lane roundabouts. They're convenient for U-turns, for example.
For anything above that where I have to cross lanes to get to the center circle and then cross lanes again to get back out and exit, I'd rather just have a conventional traffic light-controlled intersection. (I try to minimize lane changes when I drive.)
Here in France they have both types of roundabouts, yield-to-left-on-entry and yield-to-right. They are well signaled, so there is no confusion. The latter type is less common and seems to be mostly in less-busy areas. I'm not sure why they still use them though. Is it because you have better visibility to the right, since you're already in the intersection? It's an interesting design choice.
Safety aside, roundabouts lower traffic significantly by never forcing cars to stop.
Congestion increases as cars need to stop because of the inevitable latency propagating along the tails, and having more than one traditional intersections along the way can only make things even worse, so any solution to prevent cars from slowing down to a stop would mitigate those effects.
Amazing to see a "What is a roundabout?" article living in UK. The way they are put in over here you get the idea traffic engineers not only love them, they are in love with them. I largely detest them, if I'm very honest. They can be done really well, but most aren't.
Interesting that there are no listed downsides. I saw a more balanced article a while back and recall that it listed cost (especially of the additional real estate, since roundabouts are larger) as being one downside. And in built-up cities, it's basically impossible to convert traditional intersections to roundabouts, because there's simply no room.
It is nice to not have to pay for replacement signals, or have to deal with power outages that kill the signals though.
Roundabouts are great (and common where I live), but a downside is they can be difficult for pedestrians to cross. You need crossings that are set back from the exits, but this also makes it a longer path for the pedestrian.
There are roundabouts in England that are just a painted white circle in the middle of the intersection. Those work once the population knows how to handle roundabouts though. In the US, people barely comprehend regular roundabouts and in my town the larger one actually has traffic lights controlling the roundabout. So all the cost of the roundabout + all the cost of lights but none of the traffic flow benefits.
[+] [-] devnull3|2 years ago|reply
When visiting for the first time on a specific spiral roundabout:
1. Lane markings are faded
2. You do not know the specific lane unless you come very close to it and have to make a quick decision
3. Often due to queued traffic you cannot even see the lane marking until its too late.
Because of this I have seen people change lanes on a roundabout because they made a mistake and its dangerous.
[1] https://www.google.com/maps/place/Sainsbury's/@51.5080462,-0...
[+] [-] Enginerrrd|2 years ago|reply
Also, on the small side where you have traffic circles rather than roundabouts, those also suck.
[+] [-] globular-toast|2 years ago|reply
The problem is road users new to the road do not know which lane to be in already and they are pressured to go fast. The instant it looks like they've chosen a lane, a driver from behind who is familiar with the layout closes the gap in the other lane, trapping them.
This can be mitigated a bit by the first user having the confidence to slow down and straddle lanes until they are sure of the correct lane, but it's surprising how quickly such opportunities are missed.
The real problem is familiarity with lane layouts allows the road to operate at far higher capacity then normally possible and with less maintenance. They are squeezed to their limits in morning rush hours comprised of mostly familiar users. You'll even see users observing essentially invisible road markings because they're doing it from memory. No chance of you're unfamiliar with the road. Roads start to fail way before 100% capacity, but these lane markings allow that to be squeezed further during rush hours.
[+] [-] throw0101a|2 years ago|reply
* https://www.youtube.com/watch?v=e6TsX9Ob91w
I'm more curious about the straight-through path of [1] above.
[+] [-] gvurrdon|2 years ago|reply
https://www.google.com/maps/@51.7874467,-1.278506,17.57z?ent...
Coming out of Oxford on the A4144 there are two lanes; the left lane is for taking the first two turns and the right lane for the remaining three. But, drivers unfamiliar with the layout who haven't seen the markings, or who fancy jumping the queue, will sometimes use the left hand lane to go straight ahead onto the A44. There's a similar situation coming from the A40 to the East.
I've seen a few accidents there and even been involved in one as a result of this (someone tried to undertake me at speed as I exited, and caused a collision, 100% their fault according to our insurers).
[+] [-] ikekkdcjkfke|2 years ago|reply
[+] [-] michaelteter|2 years ago|reply
I live in the Netherlands, where roundabouts are very common. In many cases, they are an improvement.
But NL is also a huge bike country. And at most roundabouts, bikes have right of way. So as a car driver, you have to worry about other cars as well as bikes which may turn (go away from the roundabout) or continue (cross the adjacent road circularly around the roundabout.
In good visibility conditions, it's ok. And by OK, I mean it can still really f* up car traffic, especially when it is a high traffic area not far from a school. In lower vis conditions, and/or when electric higher speed bikes are concerned, it becomes a whole new kind of danger.
I would argue that the benefits of roundabouts diminish or fully disappear when the number of lanes exceeds 2, or when traffic lights are added to roundabouts, or (and!) especially when bike paths intersect with and circulate around the roundabouts.
[+] [-] mhandley|2 years ago|reply
[+] [-] LRVNHQ|2 years ago|reply
The fact that it's on a case-by-case basis an not actually a consistent traffic law is really awful. To add insult to injury, the only signage is usually a yield sign painted on the road that is invisible as soon as it's dark and the road is wet. And this is of course further combined with the absolute scandalous amount of cyclists who don't have lights at night and are dressed in fully dark clothes.
Roundabouts are already a traffic situation that require heightened attention as a driver, so in the interest of safety I believe crossing cyclists should yield to cars at the exit. It's too many things to worry about otherwise. But at the very least, make it the same everywhere so it's always absolutely clear to both drivers and cyclists who has the priority.
[+] [-] nkozyra|2 years ago|reply
I hate these so much. Seems to break the purpose of a roundabout in the first place - to let a single entry and exit pattern dictate the traffic.
Stoplights in them fundamentally break their benefit, which is smooth, one-way flow.
[+] [-] rwmj|2 years ago|reply
This is near where I live and it is indeed safe, mainly because everyone drives incredibly slowly and cautiously since the experience is scary as hell.
[+] [-] josephg|2 years ago|reply
Apparently there are fewer accidents on the roads when the traffic lights aren’t working. The reason is exactly that - everyone is terrified and drives really slowly to make up for it.
[+] [-] marginalia_nu|2 years ago|reply
[+] [-] hermitcrab|2 years ago|reply
[+] [-] cryptoegorophy|2 years ago|reply
[+] [-] VincentEvans|2 years ago|reply
We could accomplish the same with other forms of creative driver-hostile road construction and deliberately unproductive signage.
[+] [-] rcpt|2 years ago|reply
Only one result and it's not even about roundabouts.
This is how American traffic engineering is done.
[+] [-] ehnto|2 years ago|reply
There is a train station about 500 meters behind the workshop, as the crow flies. I thought I would just drop my car off, walk to the train, head into the city.
It took 45 minutes of detours and a lot of sketchy sections to actually get to the train station. Lucky to have the suburban train for sure, but this particular old suburb had assumed everyone was in a car, and it simply hasn't put in the work to make it traversable to pedestrians. No sidewalks, lots of dead end roads and uneccessary fences. At one point I was staring at the station, with no way to get to it. Looong impermeable business parks etc. I just wasn't meant to be there by design.
[+] [-] davidw|2 years ago|reply
[+] [-] CalRobert|2 years ago|reply
[+] [-] lobochrome|2 years ago|reply
[+] [-] buro9|2 years ago|reply
https://i.imgur.com/4pMhdMl.gif
[+] [-] Zanni|2 years ago|reply
[1] https://www.apsed.in/post/conflict-points-at-intersection
[+] [-] moribvndvs|2 years ago|reply
There are two roundabouts near me. The same two problems are rampant.
1. Failure to yield and yoloing into the circle at or nearly at full speed. One of the circles has a full stop sign, where some drivers seem to think that just because they stopped they are entitled to go next and the traffic already in the circle should and will stop to let them go, like a four way. The other doesn’t have stop sign, and I think people take the lack of one to mean they don’t have to yield or in any way pay attention because, hey, no stop sign. Admittedly, part of this is due to shitty design of the circles themselves.
2. Cars in the circle suddenly exiting without signaling, often veering across the outer lane of traffic. Part of this is driver’s education issue (I don’t think they taught us about roundabouts when I got my license several decades ago), part is the fact that in general people are allergic to signaling and have no awareness of other vehicles around them, as we have the same problem on highways.
Perhaps this is more of an awkward transitional period for their use in the States, but honestly I think the bigger problem is we on average have very poor roadmanship and inconsistent road design.
[+] [-] Fatnino|2 years ago|reply
[+] [-] rapnie|2 years ago|reply
[+] [-] osullish|2 years ago|reply
[+] [-] grecy|2 years ago|reply
Four way stops do not exist (I've never seen one in all of Australia), and they are still the strangest concept for me living in Canada. They feel like a colossal waste of time and energy, and vastly worse than roundabouts.
[+] [-] hristov|2 years ago|reply
Well with a roundabout if you just go straight ahead you hit the center circle. Good roundabouts always have a slight hill and some kind of barrier (a tree or some kind of statue) in the center so that the guy that just goes straight through will hit something in the center and wont come out the other side and will thus be less likely to kill an innocent person.
Single lane roundabouts are usually a good idea if the cost justifies it. Double and more lane roundabouts probably should be avoided in the US; they include rather obscure rules as to which lane you are allowed to drive in at any moment and americans do not like to learn new rules.
[+] [-] Jtsummers|2 years ago|reply
She kept insisting I turned in front of her (technically true, I was in a roundabout). She was arrested for drunk driving, and, later on, fined for all the flowers she damaged in the circle and the median she also ran over on her way into the intersection.
[+] [-] dfxm12|2 years ago|reply
Interestingly enough, a new roundabout was installed in my neighborhood. We considered something pretty to look at in the middle, but the city said no way. "Emergency vehicles need to be able to go through the middle at full speed". Meanwhile, busses have zero issues negotiating the circle at normal driving speeds...
[+] [-] KaiserPro|2 years ago|reply
https://www.youtube.com/watch?v=xTk_kPeA63c (turn the sound off, its just road noise) This is what happens when you go full bore into a big roundabout.
This kind of roundabout is used to join one large road to one or more small road (think two lanes going from 6-12 on the clock, with single lane road at 3 & 9)
In the UK, we don't normally have stop signs, as most junctions have clear rights of way (https://www.rac.co.uk/drive/advice/road-safety/uk-road-marki... see "Give way to traffic on major road") In suburban roads, roundabouts are often used instead of stop signs. It allows much freer flowing of traffic in both heavy and light traffic.
Just don't look up the magic roundabout, thats just fucking batshit, we only have one. The reason why they keep it is because there is literally nothing else interesting about the place.
[+] [-] boricj|2 years ago|reply
It also doesn't fully protect vehicles already inside the roundabout. My father got rear-ended once while inside a roundabout by a possibly distracted driver and the car was a near write-off.
The main advantage of roundabouts is traffic fluidity. When compared to intersections with stop signs or traffic lights, unless it is full you can often enter a roundabout without coming to a complete stop first.
[+] [-] gumby|2 years ago|reply
[+] [-] _zamorano_|2 years ago|reply
They're perfect for crossings with low to middle traffic. No useless waiting time, good visiblity and no need for traffic lights.
For heavy traffic, though, they're useless as the car flow of one entry/exit can take over the roundabout and block all other entries.
Also, it seems hard to understand for many drivers that regulations regarding changing lanes don't change in a roundabout. So more than 3 lanes are not advisable in my opinion.
[+] [-] severino|2 years ago|reply
Inside cites, those traffic lights in intersections were usually also semaphores for pedestrian crosswalks. So when you replace the intersection with a roundabout, you usually keep the traffic lights for the crosswalks alone. At the speed a car exits a roundabout, a non-regulated crosswalk could be quite dangerous.
[+] [-] andrepd|2 years ago|reply
[+] [-] throw0101a|2 years ago|reply
Not wrong, but traffic lights can be added to roundabouts as well ("signalized roundabouts")
* https://www.youtube.com/watch?v=XCrAPcUzOdw
So if an intersection is (e.g.) four-way, and one particular entrance monopolizes things than it can be given red at times and the others green (and than one-green/three-reds).
See (e.g.) "Performance and Safety of Roundabouts with Traffic Signals" by Tracz and Chodura:
> The paper presents designs, advantages and some drawbacks of various layouts of roundabouts with traffic signals, used in urban arterials on crossings with large traffic volumes. The authors analyze signal settings with alternative phasing used at intersections that can provide the intersection capacity of about 6500 veh/h in 2x2 lanes arterials or even 8000 veh/h in 2x3 lanes arterials. Accident statistics for roundabouts with traffic signals in Krakow are also given and discussed. In addition, presented are practical examples of changes of signalized roundabouts geometry; reconstruction into a form of turbo- roundabout and its effects regarding traffic safety and good performance.
* https://pdf.sciencedirectassets.com/277811/1-s2.0-S187704281...
And §8.1 Traffic Signals at Roundabouts:
* https://www.fhwa.dot.gov/publications/research/safety/00067/...
Also:
* https://www.access-board.gov/research/prow/literature-rounda...
[+] [-] oldbbsnickname|2 years ago|reply
PS: One place that doesn't do proper traffic design (or architecture): Texas. They insist on placing massive concrete dividers everywhere and have camouflaged by wear obstacles in the middle of paths that are injurious to bicyclists. It's nothing like the Netherlands where there aren't many random, dangerous surprises.
[+] [-] a_e_k|2 years ago|reply
For anything above that where I have to cross lanes to get to the center circle and then cross lanes again to get back out and exit, I'd rather just have a conventional traffic light-controlled intersection. (I try to minimize lane changes when I drive.)
[+] [-] citizenkeen|2 years ago|reply
[+] [-] gniv|2 years ago|reply
[+] [-] squarefoot|2 years ago|reply
[+] [-] alex-moon|2 years ago|reply
[+] [-] gnicholas|2 years ago|reply
It is nice to not have to pay for replacement signals, or have to deal with power outages that kill the signals though.
[+] [-] polemic|2 years ago|reply
[+] [-] jgeada|2 years ago|reply
[+] [-] 123pie123|2 years ago|reply
have you seen the mini roundabout yet?
people kind of follow the rules but sometime cut over the middle - especially on the very small ones
[+] [-] gniv|2 years ago|reply
[+] [-] ceejayoz|2 years ago|reply