The UK is replacing roundabouts with traffic lights; US is doing the opposite(theguardian.com)
theguardian.com
The UK is replacing roundabouts with traffic lights; US is doing the opposite
http://www.theguardian.com/cities/2015/oct/19/traffic-lights-roundabouts-way-out
19 comments
I don't see roundabouts as a replacement for traffic lights in the US. Above a certain traffic volume, you'll almost always want to move to traffic lights anyway. They're actually a replacement for the 4-way Stop - a ridiculous type of intersection that ought not to exist.
> 4-way Stop - a ridiculous type of intersection that ought not to exist.
Ought not to exist in places like Europe, perhaps.
The four-way stop has the virtue that it is easy for Americans and Canadians to understand.
1. Everyone arriving at the four-way pretends to stop by slowing down to around 20 mph.
2. Regardless of who arrived first, if two or more vehicles take conflicting paths, the biggest asshole goes first. (The algorithm for determining this party takes into account factors such as vehicle size, general socio-economic background, minimum velocity achieved during four-way stop approach, and their apparent perception of where the white stop line is.)
3. When two vehicles take nonconflicting paths (e.g. two directly facing vehicles both go right) they need not acknowledge each others' existence.
4. Only left turns must be indicated. If someone fails to indicate while approaching, they are assumed to be going straight or turning right. Should that be incorrect, the situation is resolved by a fair division of rights: right of way is given to the non-indicating left turner($), whereas the inconvenienced/threatened party is given the right to several prolonged honks of the horn.
5. Where visibility over the other converging roads is not obstructed by building, bush or otherwise, the four-way stop may be completely ignored when not approached by another vehicle with an estimated arrival time that is within a second, either way, of one's own arrival time. (Pedestrians and cyclists may optionally be counted as vehicles at the driver's discretion.)
Who needs roundabouts?
----
$. The governing principle here is consistency -- with rule (2).
Ought not to exist in places like Europe, perhaps.
The four-way stop has the virtue that it is easy for Americans and Canadians to understand.
1. Everyone arriving at the four-way pretends to stop by slowing down to around 20 mph.
2. Regardless of who arrived first, if two or more vehicles take conflicting paths, the biggest asshole goes first. (The algorithm for determining this party takes into account factors such as vehicle size, general socio-economic background, minimum velocity achieved during four-way stop approach, and their apparent perception of where the white stop line is.)
3. When two vehicles take nonconflicting paths (e.g. two directly facing vehicles both go right) they need not acknowledge each others' existence.
4. Only left turns must be indicated. If someone fails to indicate while approaching, they are assumed to be going straight or turning right. Should that be incorrect, the situation is resolved by a fair division of rights: right of way is given to the non-indicating left turner($), whereas the inconvenienced/threatened party is given the right to several prolonged honks of the horn.
5. Where visibility over the other converging roads is not obstructed by building, bush or otherwise, the four-way stop may be completely ignored when not approached by another vehicle with an estimated arrival time that is within a second, either way, of one's own arrival time. (Pedestrians and cyclists may optionally be counted as vehicles at the driver's discretion.)
Who needs roundabouts?
----
$. The governing principle here is consistency -- with rule (2).
The four-way stop has the virtue that it is easy for Americans and Canadians to understand.
I realize you're being facetious, but that statement is so untrue for the Pacific Northwest of the U. S. that _Portlandia_ even devoted part of an episode to it.
And, surprise, they have trouble with roundabouts, too. Though unlike 4-way stops, it looks like mossbacks are starting to grok roundabouts.
I realize you're being facetious, but that statement is so untrue for the Pacific Northwest of the U. S. that _Portlandia_ even devoted part of an episode to it.
And, surprise, they have trouble with roundabouts, too. Though unlike 4-way stops, it looks like mossbacks are starting to grok roundabouts.
Where exactly do you live? I've driven all over the east coast and have never, ever seen any of this to be remotely true.
My guess is west coast.
(1) is even lovely titled "California Pit Stop". Because people from California don't know to stop on the white line (or have a terrible perception of where the front of their vehicle is) many people stop in the pedestrian crossing. They proceed to roll through the 4-way stop so long as they don't see anyone. Although 20mph is cutting it, perhaps 10-15? Either way they never come to a full and complete stop.
(2) is because seemingly nobody knows 4-way stops are FIFO and believe it's "Straights first then turns". If paths are non-conflicting, both people will go at the same time.
(4) is only partially true. If you're in a rush, left-signalling is not necessary; it's user discretion. Also all straight/right turn lanes are assumed to be straight, since nobody signals right turns. This is a reminder that it is your fault for not turning right due to potential oncoming traffic and the car behind you will occasionally honk in irritation that you didn't pull out in front of traffic that was potentially continuing straight.
Driving in the L.A area is hell.
(1) is even lovely titled "California Pit Stop". Because people from California don't know to stop on the white line (or have a terrible perception of where the front of their vehicle is) many people stop in the pedestrian crossing. They proceed to roll through the 4-way stop so long as they don't see anyone. Although 20mph is cutting it, perhaps 10-15? Either way they never come to a full and complete stop.
(2) is because seemingly nobody knows 4-way stops are FIFO and believe it's "Straights first then turns". If paths are non-conflicting, both people will go at the same time.
(4) is only partially true. If you're in a rush, left-signalling is not necessary; it's user discretion. Also all straight/right turn lanes are assumed to be straight, since nobody signals right turns. This is a reminder that it is your fault for not turning right due to potential oncoming traffic and the car behind you will occasionally honk in irritation that you didn't pull out in front of traffic that was potentially continuing straight.
Driving in the L.A area is hell.
Note that going at the same time for nonconflicting paths is logical: at least if everyone reliably indicates lefts! Intersection controls exist for resolving the conflict over a resource: a piece of road needed by multiple vehicles which they can't all occupy at the same time. If there is no conflict, the control serves no purpose to that case, other than "traffic calming".
Even when the user signals - there is no guarantee they will be actually be turning. Some users think it is in good form to signal an upcoming lane merge while stopped at an intersection.
I guess the point we're both trying to get across is that people on the west coast, as a whole, don't seem to understand how to drive. :) It was motivation enough for me to buy a dashcam.
I guess the point we're both trying to get across is that people on the west coast, as a whole, don't seem to understand how to drive. :) It was motivation enough for me to buy a dashcam.
I live in Los Angeles, particularly Beverly Hills / Century City, and am surprised when I see people acting civil at 4-way stops.
West coast Canada. (See mikestew's sibling comment to yours).
Or my personal favorite in Sacramento, roundabout with some stop signs sprinkled in. I hear horns and accidents daily...
https://www.google.com/maps/@38.5801855,-121.4694376,3a,75y,...
https://www.google.com/maps/@38.5801855,-121.4694376,3a,75y,...
Roundabouts with stop signs are insane, i see them in Ontario too and cannot figure them out.
Coming from Australia (that admittedly at times tends to over uses roundabouts) all i can ever wonder when i see a quiet road with traffic lights, or a seemingly pointless 4 way stop sign is "WHY IS THIS NOT A ROUNDABOUT?" I agree at a certain volume there are better alternatives, but there are massive benefits for a very long time and if you have the room for a large enough roundabout they can handle massive volume.
Here is a decent example that is just near Newcastle University in Australia. Traffic lights here would likely be much slower: https://goo.gl/maps/MPhri8vrt5M2
Side note: North America, please stop abusing using "stop" signs. No one stops anyway, just make them "Yield" signs unless its a seriously bad intersection.
Coming from Australia (that admittedly at times tends to over uses roundabouts) all i can ever wonder when i see a quiet road with traffic lights, or a seemingly pointless 4 way stop sign is "WHY IS THIS NOT A ROUNDABOUT?" I agree at a certain volume there are better alternatives, but there are massive benefits for a very long time and if you have the room for a large enough roundabout they can handle massive volume.
Here is a decent example that is just near Newcastle University in Australia. Traffic lights here would likely be much slower: https://goo.gl/maps/MPhri8vrt5M2
Side note: North America, please stop abusing using "stop" signs. No one stops anyway, just make them "Yield" signs unless its a seriously bad intersection.
> North America, please stop abusing using "stop" signs. No one stops anyway, just make them "Yield" signs unless its a seriously bad intersection.
Maybe outside of cities. In cities, they are the best thing ever for pedestrians.
Maybe outside of cities. In cities, they are the best thing ever for pedestrians.
I disagree. I think roundabouts like this one are much better for pedestrians:
https://www.google.com/maps/@38.5513462,-121.7200079,3a,75y,...
As a driver, there's 2 places I need to watch for pedestrians: just before I get into the roundabout, and right at the exit. And the place I need to watch for is the width of a lane of traffic that's directly in front of me. Compared to a 4-way stop. Now there's nearly 180 degrees I need to look: pedestrians crossing the street directly in front of you (so directly left and right), pedestrians crossing the direction you're going to, and the 3 other cars that are stopped at the lights trying to figure out whose turn it really is, since only one person can go because pedestrians are blocking. And then when someone starts going someone inevitably goes into the intersection even though it's not their turn. And bikes/pedestrians not even stopping and looking before going into the intersection. 4-way stops are a complete cluster when there's heavy pedestrian traffic and even a moderate amount of car traffic.
https://www.google.com/maps/@38.5513462,-121.7200079,3a,75y,...
As a driver, there's 2 places I need to watch for pedestrians: just before I get into the roundabout, and right at the exit. And the place I need to watch for is the width of a lane of traffic that's directly in front of me. Compared to a 4-way stop. Now there's nearly 180 degrees I need to look: pedestrians crossing the street directly in front of you (so directly left and right), pedestrians crossing the direction you're going to, and the 3 other cars that are stopped at the lights trying to figure out whose turn it really is, since only one person can go because pedestrians are blocking. And then when someone starts going someone inevitably goes into the intersection even though it's not their turn. And bikes/pedestrians not even stopping and looking before going into the intersection. 4-way stops are a complete cluster when there's heavy pedestrian traffic and even a moderate amount of car traffic.
I drive through that particular roundabout multiple times a day. At least 5% of the vehicles I encounter there will stop and yield to other traffic that is only approaching the roundabout, or more maddeningly, stop in the middle when they see traffic approaching.
I've had to slam on my brakes because someone wasn't stopping (and then they waved at me to thank me for stopping for them...). But that was once after the hundreds of time through there. I know it's not quite fair since they're at different places, but compare the roundabout to something like 3rd and F at 12:30. It's a nightmare there, whereas even when there's a bus letting off 60 people walking to the apartments by that roundabout, it's not that unpleasant.
I don't know about you, but in my mind when I see a yield sign...i'll stop if it makes sense. I don't feel that the stop sign changes my desire to not run over someone all that much. As a driver I want the flexibility to make a judgement on if stopping is required based on the situation. Maybe a red sign makes sense to provide additional information ("this is a bad intersection, be extra careful!") but I don't like that the sign requires me to stop, even if it doesn't make sense.
This goes back to my ongoing complain that driving laws are very relaxed (i.e. speed limits never complied with - but for some reason we still have them?) and its causing an inconsistent approach to driving. For example, hardly anyone signals when turning or changing lanes, and if they do its by the time they're already well into the turn. Its just bad driving, dangerous and quiet frankly while I do not want stricter laws, or more enforcement...i'd appreciate some consistency in how people behave on the roads.
To me this is just adds to the vibe of the 'broken window' issue with roads and how people interact with them right now.
This goes back to my ongoing complain that driving laws are very relaxed (i.e. speed limits never complied with - but for some reason we still have them?) and its causing an inconsistent approach to driving. For example, hardly anyone signals when turning or changing lanes, and if they do its by the time they're already well into the turn. Its just bad driving, dangerous and quiet frankly while I do not want stricter laws, or more enforcement...i'd appreciate some consistency in how people behave on the roads.
To me this is just adds to the vibe of the 'broken window' issue with roads and how people interact with them right now.
Agreed. And besides which stop signs may get treated as yield but yield signs are treated even worse.
The only thing better than stop signs for pedestrians (and I'd say they're better than traffic lights with dedicated pedestrian signals in most cases) is probably total chaos (as per some cities in switzerland) where there's seven way intersections with trams and no clear boundary between sidewalk and road, and motorists just need to stop and figure it out.
The only thing better than stop signs for pedestrians (and I'd say they're better than traffic lights with dedicated pedestrian signals in most cases) is probably total chaos (as per some cities in switzerland) where there's seven way intersections with trams and no clear boundary between sidewalk and road, and motorists just need to stop and figure it out.
Cars still would still have to stop for pedestrians at the yield sign. Works very well in other countries. If there are too many pedestrians, just put a traffic light up to regulate traffic between pedestrians and cars. Key here though is that the light isn't on a timer but actually adjusts to someone pressing the button or a car rolling over a sensor in the ground.
For true insanity you need to go to Washington DC which has roundabouts with divided lanes, pedestrian crossings, traffic lights, stop signs, and turning lanes.
https://www.google.com/maps/place/Washington,+DC/@38.9092507...
https://www.google.com/maps/place/Washington,+DC/@38.9020455...
https://www.google.com/maps/place/Washington,+DC/@38.9092507...
https://www.google.com/maps/place/Washington,+DC/@38.9020455...
Traffic circles and rotaries are not modern roundabouts.
If any of the entry lanes has a stop sign, it’s not a modern roundabout.
If you could play a game of football in the center landscaped area, it’s not a modern roundabout.
If the circular roadway has a stop sign, yield sign or signal, it’s not a modern roundabout.
If you don’t have to slow down to enter it, it’s not a modern roundabout.
If you have to change lanes in the circular roadway to exit, it’s not a modern roundabout.
If you can easily drive faster than 20 mph in the circular roadway, it’s not a modern roundabout.
If it has a park for pedestrians, or a building, in the middle, it’s not a modern roundabout.
This is pretty common in France. Every major city has like dozens of these kinds of intersections (e.g. behind the Trocadero, around the Arc de Triomphe, etc)
My recollection is that the roundabouts in Paris are free for alls (a whole different kind of crazy, but it seems to work). I checked the satellite images of the circle around the arc de triomphe and it seems to be as I remember. There may be lights regulating entry into the circle, but the lanes aren't divided. And if I recall correctly pedestrians access the middle via underground walkway.
I just checked via Google street view and it confirms my memory.
I just checked via Google street view and it confirms my memory.
That's not really a roundabout though, it's a traffic circle, which is a replacement for speed bumps. I have one of those near my house in Sacramento as well.
Live in Sacramento, the half-roundabouts drive me crazy. Here's another:
https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,...
https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,...
Neighborhood traffic circles are not modern roundabouts.
Many people confuse other and older styles of circular intersections with modern roundabouts. East coast rotaries, large multi-lane traffic circles (Arc D’Triomphe, Dupont Circle), and small neighborhood traffic circles are not modern roundabouts. If you want to see the difference between a traffic circle, a rotary (UK roundabout) and a modern roundabout (UK continental roundabout), go to http://tinyurl.com/kstate-RAB to see pictures. And here’s another site that shows the difference between an older rotary and a modern roundabout: http://tinyurl.com/bzf7qmg
There are some of these in Palo Alto, as well. I don't think they tend to result in accidents, but I never really understood the point of putting a stop sign on a roundabout.
If I remember correctly, the justification of these here is that they are better for bikes than 4-way stops (which is true, but they're probably not the optimal solution).
https://www.google.com/maps/@37.4420644,-122.1552851,3a,75y,...
If I remember correctly, the justification of these here is that they are better for bikes than 4-way stops (which is true, but they're probably not the optimal solution).
https://www.google.com/maps/@37.4420644,-122.1552851,3a,75y,...
If it has a stop sign, it is a traffic circle with different rules than a modern roundabout.
Wait. Is that a 2-way stop? That looks dangerous as hell. If I come upon a stop sign with a island in the middle of the intersection, it is easy to assume that everyone has to stop.
There are a lot of 2-way stops in that area.
My wording is kinda of muddy. A 2-way stop isn't itself dangerous. I think seeing an island makes the intersection appear more like a roundabout, and makes drivers approaching from the side streets think that all entrances to that roundabout will have a stop sign.
DMV manual fail.
All way stops have a small sign below the stop sign that says ALL WAY. Any stop sign without that rider sign is not at an all way stop intersection.
Yup. I am a fan of this sign (https://commons.wikimedia.org/wiki/File:Cross_traffic_does_n...) instead of this one (http://safety.fhwa.dot.gov/intersection/resources/casestudie...)
If you look a few blocks away there's that sign: https://www.google.com/maps/@38.5676945,-121.4748759,3a,75y,...
That's not a roundabout. That is a 2-way stop with a speed-abatement island.
There are actually a lot of good cases for roundabout over intersection with traffic lights, but I think that's really something that needs to be decided on a per intersection basis.
To me the best replacement for a 4-way stop is really giving one street the right of way and using a yield sign for the less important street. However, that seems to be unheard of in the US.
That can make it really hard for the less important street to actually get across, if there are cars coming frequently enough on the more important street. Perhaps more importantly, a yield only works if the yielding street has adequate visibility, and it's primarily only used when merging into a lane (as opposed to crossing an intersection) because trying to keep track of oncoming traffic in both directions and determining when it's safe to cross can be quite hazardous.
In general, the 4-way stop is something that should be rarely used, but is appropriate in some cases. There's a 4-way stop near where I live that I think is very appropriate; the busier road isn't so busy that a stop sign causes traffic to pile up, but is busy enough that if it were given unimpeded flow, the cross street would have difficulty crossing. But installing a traffic light would likely cause longer delays on average for cars, and would also be a bit of a problem as the intersection is at the top of a hill and a traffic light would cause traffic on the main street to back up down the hill (and you don't want people to stop on an uphill if they don't have to).
FWIW, if topography allowed, this would make for a good roundabout spot. But it would take up a bit more space than the (admittedly large) intersection, and the topography of the hill would cause a problem. I suspect that something similar could be said of all appropriate 4-way stop signs, that they'd be better as roundabouts if space and/or topography wasn't a concern.
In general, the 4-way stop is something that should be rarely used, but is appropriate in some cases. There's a 4-way stop near where I live that I think is very appropriate; the busier road isn't so busy that a stop sign causes traffic to pile up, but is busy enough that if it were given unimpeded flow, the cross street would have difficulty crossing. But installing a traffic light would likely cause longer delays on average for cars, and would also be a bit of a problem as the intersection is at the top of a hill and a traffic light would cause traffic on the main street to back up down the hill (and you don't want people to stop on an uphill if they don't have to).
FWIW, if topography allowed, this would make for a good roundabout spot. But it would take up a bit more space than the (admittedly large) intersection, and the topography of the hill would cause a problem. I suspect that something similar could be said of all appropriate 4-way stop signs, that they'd be better as roundabouts if space and/or topography wasn't a concern.
Exactly... it's almost an intermediate step... too many locations move from 2/4-way stops straight to lights, when they rarely see enough traffic to really justify it... I think more rural and suburban locations are probably best for this...
If you have more than 2 lanes of traffic in either direction, they're a bad idea... I've seen them used pretty well for certain highway on/off ramps too.
If you have more than 2 lanes of traffic in either direction, they're a bad idea... I've seen them used pretty well for certain highway on/off ramps too.
It depends where you live. Personally, I love roundabouts and so does my city.
my city has a few normal roundabouts, and then one insane version where the cars in the roundabout have to yield to people entering. its pretty bad...
The question should be, what is best for this particular intersection in the near future? The two designs have different characteristics.
My understanding is that roundabouts are best when traffic is low, when it gets heavy they become much less efficient. Lights, while a lot of overhead in low traffic, scale better. There's also the question of space required.
Since the UK may have too many roundabouts due to traffic growth, and the US virtually none, they could both be building the opposite and making the right choice.
My understanding is that roundabouts are best when traffic is low, when it gets heavy they become much less efficient. Lights, while a lot of overhead in low traffic, scale better. There's also the question of space required.
Since the UK may have too many roundabouts due to traffic growth, and the US virtually none, they could both be building the opposite and making the right choice.
One of the great advantages of roundabouts is that they're approximately "fair" whereas traffic lights are not.
What I mean is that a traffic light is very arbitrary and stops people who just barely didn't make the cutoff. Multiply that by 5, 10, or 20 traffic lights on a journey and an extra minute at each one can add up. So people have incentive to run the light and shave the 30 seconds or a minute. But then when people run the light, it slows down the cross-road who has to wait extra for the road to clear, despite it being "their turn". So then people on that side have an incentive to run the light, because they got wrongfully cutoff by the arbitrariness and the other jerks running the light first. Rinse and repeat for a few cycles and it's easy to see that this is not a good situation.
Traffic circles on the other hand don't suffer from this as there isn't arbitrariness on such a 'long' timescale. If you have to wait for a couple of extra cars it's only a few seconds, versus a minute or so. Because it's just a couple of seconds, people have less to lose and are more inclined to be nice. Which ultimately means that driving is more pleasant, even if it's not as efficient.
I also might disagree with the idea that roundabouts aren't effective at high traffic levels. https://www.youtube.com/watch?v=lwHfibl1AoI
What I mean is that a traffic light is very arbitrary and stops people who just barely didn't make the cutoff. Multiply that by 5, 10, or 20 traffic lights on a journey and an extra minute at each one can add up. So people have incentive to run the light and shave the 30 seconds or a minute. But then when people run the light, it slows down the cross-road who has to wait extra for the road to clear, despite it being "their turn". So then people on that side have an incentive to run the light, because they got wrongfully cutoff by the arbitrariness and the other jerks running the light first. Rinse and repeat for a few cycles and it's easy to see that this is not a good situation.
Traffic circles on the other hand don't suffer from this as there isn't arbitrariness on such a 'long' timescale. If you have to wait for a couple of extra cars it's only a few seconds, versus a minute or so. Because it's just a couple of seconds, people have less to lose and are more inclined to be nice. Which ultimately means that driving is more pleasant, even if it's not as efficient.
I also might disagree with the idea that roundabouts aren't effective at high traffic levels. https://www.youtube.com/watch?v=lwHfibl1AoI
The problem with roundabouts is starvation.
I grew up in France, which has more than 50% of the world's roundabouts. They are everywhere.
Where I am from, there is a roundabout at the intersection of a major road and a small road with little traffic. During rush hour, it is impossible to enter the roundabout coming from the small road because there is a continuous flow of cars coming from the major road. It is truly an uninterrupted flow of cars because the cars come from another roundabout...
Before the roundabout, there was no problem because there was a light that would be always be green for the main road expect when a car was detected on the small road. It was optimal.
I grew up in France, which has more than 50% of the world's roundabouts. They are everywhere.
Where I am from, there is a roundabout at the intersection of a major road and a small road with little traffic. During rush hour, it is impossible to enter the roundabout coming from the small road because there is a continuous flow of cars coming from the major road. It is truly an uninterrupted flow of cars because the cars come from another roundabout...
Before the roundabout, there was no problem because there was a light that would be always be green for the main road expect when a car was detected on the small road. It was optimal.
Thanks for sharing! That makes sense that roundabout traffic flows can't be too lopsided or else you'll get this kind of behavior. It wasn't something I had ever thought of.
Not a traffic engineer, but it is what I was told by Kiwis when driving in NZ, and it matched my experience. Driving a particular roundabout was a breeze at lunch (much better typically than a light), but took a very long time just to get into it during the 5pm rush.
Traffic lights have other trade-offs that can be tweaked such as timing length, it is hard to say what is best without knowing more.
Traffic lights have other trade-offs that can be tweaked such as timing length, it is hard to say what is best without knowing more.
Right, for sure! I'm not suggesting that my analysis is correct, it's just something I've noticed in a big city with a lot of traffic lights. Red-running is endemic during rush hour, but I see much better behavior at the roundabouts.
One of the bummers of traffic lights is that they tend to be more efficient with longer light cycles since you amortize the 'start up cost' of getting vehicles moving through the intersection over a longer period of vehicles moving at full speed. But the downside is that this increases the perceived unfairness because a one car length difference now means an even longer arbitrary delay.
I'm not a traffic engineer either but living in a city with horrible traffic it is something I think about.
One of the bummers of traffic lights is that they tend to be more efficient with longer light cycles since you amortize the 'start up cost' of getting vehicles moving through the intersection over a longer period of vehicles moving at full speed. But the downside is that this increases the perceived unfairness because a one car length difference now means an even longer arbitrary delay.
I'm not a traffic engineer either but living in a city with horrible traffic it is something I think about.
Traffic lights with magnetic sensors to detect cars and amount of cars waiting work pretty well here in California. Unless you're riding a motorcycle...
Or a bicycle, which makes the lack of an Idaho Stop law even more frustrating.
Yeah. I know some motorcyclists who have gotten off their bike to walk to corner to push the crosswalk button to get the light to change. It may not be 100% legal, but you gotta do what you gotta do.
Now that is crazy, I just look around for cops a dozen times and floor it (carefully).
The UK also has a lot of roundabouts retrofitted with traffic lights (especially at motorway junctions).
Lights in low traffic can also be low overhead, if you have adequate sensors. If you only have sensors at the line, and there's a dominant flow, set the dominant flow to green, and cycle through when someone comes up on the non-dominant flow. If you have sensors back far enough, you can leave everyone on red, and cycle to green when someone comes up.
They also seem pretty OK when traffic is moderate, but only in one direction. The minor flow direction pays a price but the dominant flow direction is largely unimpinged compared to a stop light or four-way stop.
There seems to be no data supporting the article's assertion that roundabouts are being replaced by traffic lights across the UK as a whole. I'll add my own anecdata: many more roundabouts are being built in my area of the UK. There are also roundabouts with traffic lights.
As a driver, I much prefer roundabouts. When I'm cycling, I just prefer roads with fewer cars and can't wait for self-driving cars, since at least they won't be driven by idiots.
There are safer roundabout designs used in Holland: http://www.aviewfromthecyclepath.com/2014/05/the-best-rounda...
As a driver, I much prefer roundabouts. When I'm cycling, I just prefer roads with fewer cars and can't wait for self-driving cars, since at least they won't be driven by idiots.
There are safer roundabout designs used in Holland: http://www.aviewfromthecyclepath.com/2014/05/the-best-rounda...
The headline makes it sound like it's a wholesale thing, but from how the article describes it, traffic agencies in both countries are discovering that some intersections are more useful, safer, etc if they had a different kind of traffic control. As information disperses, it becomes easier for engineers from different countries to share ideas and knowledge to figure out what the best course of action is for a certain type of intersection.
"Cyclists have a demonstrably harder time with roundabouts."
As the text acknowledges, a lot depends on the design of the roundabout. Just last week, we got https://bicycledutch.wordpress.com/2015/10/13/explaining-the..., which explains the current thinking of the dutch on roundabout design.
Also, roundabouts have become more popular, but traffic deaths certainly haven't gone up in the Netherlands (https://www.swov.nl/rapport/Factsheets/UK/FS_Road_fatalities...).
As the text acknowledges, a lot depends on the design of the roundabout. Just last week, we got https://bicycledutch.wordpress.com/2015/10/13/explaining-the..., which explains the current thinking of the dutch on roundabout design.
Also, roundabouts have become more popular, but traffic deaths certainly haven't gone up in the Netherlands (https://www.swov.nl/rapport/Factsheets/UK/FS_Road_fatalities...).
Really? I don't find them challenging at all. Would be even nicer is they put a protected bike ring around the outer edge so cyclists only have to watch out for the part they are crossing across.
Comment I'd made[0] on a previous article about roundabouts and their potential for confusion:
I live in Victoria, Australia, and we’ve had roundabouts for ages. I think they are very good for a certain scale of road/traffic. Mostly intersections with moderate amounts of traffic on average, and not high-speed. e.g., the main intersections within housing estates. Having too many of them instead of give-way signs drive you a little batty (I’m looking at you, Warrnambool) while really heavy traffic, major intersections work better with traffic lights.
My daughter recently got her learner license, and she has found roundabouts one of the trickier intersections to navigate. You have to read the traffic flow. This person about to enter on your right is going straight ahead, so will block you entering the roundabout[1], but they have to wait for that person coming the other way from you and going straight through, so you can slip in the gap that creates without cutting anyone else off. As with many things it is familiarity and practice that makes them work[2]. I think roundabouts work very well here for the most part, and my daughter is getting pretty good at reading the traffic. It’s not rocket science[3].
The science of roads and traffic I imagine is a surprisingly nuanced expertise involving a lot of physics and psychology. I find when I cross over the border to New South Wales I feel like a long-tailed cat in a room full of rocking chairs. I eventually figured out it was because the signage was a different distance before the intersection compared to my home state. Once I was aware I could adapt.
[0] https://news.ycombinator.com/item?id=10242816
[1] We drive on the left side of the road because Australia is in the southern hemisphere.
[2] I bet the first traffic lights caused an uproar. “Why the hell should I stop just because there’s a red light?!”
[3] Oh wait, actually, it is rocket science.
I live in Victoria, Australia, and we’ve had roundabouts for ages. I think they are very good for a certain scale of road/traffic. Mostly intersections with moderate amounts of traffic on average, and not high-speed. e.g., the main intersections within housing estates. Having too many of them instead of give-way signs drive you a little batty (I’m looking at you, Warrnambool) while really heavy traffic, major intersections work better with traffic lights.
My daughter recently got her learner license, and she has found roundabouts one of the trickier intersections to navigate. You have to read the traffic flow. This person about to enter on your right is going straight ahead, so will block you entering the roundabout[1], but they have to wait for that person coming the other way from you and going straight through, so you can slip in the gap that creates without cutting anyone else off. As with many things it is familiarity and practice that makes them work[2]. I think roundabouts work very well here for the most part, and my daughter is getting pretty good at reading the traffic. It’s not rocket science[3].
The science of roads and traffic I imagine is a surprisingly nuanced expertise involving a lot of physics and psychology. I find when I cross over the border to New South Wales I feel like a long-tailed cat in a room full of rocking chairs. I eventually figured out it was because the signage was a different distance before the intersection compared to my home state. Once I was aware I could adapt.
[0] https://news.ycombinator.com/item?id=10242816
[1] We drive on the left side of the road because Australia is in the southern hemisphere.
[2] I bet the first traffic lights caused an uproar. “Why the hell should I stop just because there’s a red light?!”
[3] Oh wait, actually, it is rocket science.
I think if the roundabouts were large, then in fact they would always be superior to traffic lights. I could probably run the math on that, but the idea is that the lights aren't sensitive to the actual flow of traffic, and often make things backed up for no reason.
But roundabouts are insensitive to where the traffic is coming from. With light traffic, this is not a problem, but with heavy traffic, if all directions are getting the same priority, it may hurt the entrances with more traffic.
In France, you see main thoroughfares have overpasses or under-passes and signals into the roundabout that it avoids. Hard to find a map, but essentially, it is to address your concern.
It's possible they're both being sensible. Roundabouts are certainly under utilised in the US (unlike those awful four-way stop signs which are particularly hellish for law-abiding cyclists) so putting more in is a good move.
However, as traffic at any particular intersection increases it eventually may make sense to replace a roundabout with a traffic light. Roundabouts can handle large amounts of traffic, but only if they're large roundabouts -- if you can't expand the actual road space then the traffic light is the best move.
However, as traffic at any particular intersection increases it eventually may make sense to replace a roundabout with a traffic light. Roundabouts can handle large amounts of traffic, but only if they're large roundabouts -- if you can't expand the actual road space then the traffic light is the best move.
Also, in my experience, roundabouts work best if traffic at all entrances/exits are roughly equal (within an order of magnitude or two)
If traffic flow becomes highly unbalanced, a constant flow of cars from the primary entrance to the primary exit can block all cars from entering the roundabout at secondary entrances. They have to wait for a car to enter at the primary entrance then take the secondary exit so before they can enter.
I was once stuck at a roundabout for 5min due to a sports event in a nearby town creating a constant flow of south to north traffic, when I wanted to go from west to east. The roundabout useally worked perfectly fine, but was broken by the abnormal traffic.
If that intersection had traffic lights, the impact on non south-north traffic would have been minimal.
If traffic flow becomes highly unbalanced, a constant flow of cars from the primary entrance to the primary exit can block all cars from entering the roundabout at secondary entrances. They have to wait for a car to enter at the primary entrance then take the secondary exit so before they can enter.
I was once stuck at a roundabout for 5min due to a sports event in a nearby town creating a constant flow of south to north traffic, when I wanted to go from west to east. The roundabout useally worked perfectly fine, but was broken by the abnormal traffic.
If that intersection had traffic lights, the impact on non south-north traffic would have been minimal.
Wow I can't even. I live in Carmel, IN - basically the roundabout capital of USA. We just built our 100th roundabout and have several more near completion. Love them. Far better than traffic lights.
So weird to see the reason we have them is due to our Mayor visiting England many years ago. Now they are going the other way. Did their mayor or someone visit us and fell in love with traffic lights?
So weird to see the reason we have them is due to our Mayor visiting England many years ago. Now they are going the other way. Did their mayor or someone visit us and fell in love with traffic lights?
Strange. I rode the entire PBP (1200km) last month in France and many of the intersections were roundabouts. I didn't see them as any better or worse for cyclists than the 4 way intersections we have today. If anything, it makes it easier for a cyclist to be on the lookout for where a car that could hit them is coming from.
I tend to hate roundabouts. They're terrifying. But for 5-ways (and more) I think they can be a better solution than the complicated signage and striping of a traditional intersection. Provided that they are low speed.
There should be a compass marking at the center of each roundabout as standard.
There should be a compass marking at the center of each roundabout as standard.
Here is a particularly terrifying roundabout: https://www.google.co.uk/maps/@51.5628134,-1.7714704,177m/da...
O hai. Welcome to Massachusetts, where the roundabouts have traffic lights, and getting from the Tufts campus to downtown Somerville becomes a game of multidimensional live-action Frogger. And that's if you HAVE a walk signal.
Dutch roundabouts are the best. Lots of videos here:
https://bicycledutch.wordpress.com/tag/roundabout/
https://bicycledutch.wordpress.com/tag/roundabout/
The overuse of roundabouts is US is in Bend OR. For some reason, I have seen at least half-a-dozen roundabouts there. Most cities, I visited in US have at most a couple of them. Bend OR is roundabout-ville.
My town put in a few roundabouts last year and I already noticed memorial flowers at one of them, not sure if for pedestrian, bicycle or car.
I could see roundabouts being an advantage on smaller one or two lane streets but beyond that it seems like it would get dangerous fast.
Why not have a roundabout with traffic lights on the entrances which are turned on at peak times only to ensure even flow.
I fucking hate roundabouts.
There. I feel better now. Thanks.
Wait, no the rage is coming back - multi-lanes!!! ahhh!! help!
There. I feel better now. Thanks.
Wait, no the rage is coming back - multi-lanes!!! ahhh!! help!