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The UK is replacing roundabouts with traffic lights; US is doing the opposite

49 points by jonathansizz 11y ago

rwmj 11y ago
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-roundabout-design-for-cyclists.html http://www.aviewfromthecyclepath.com/2014/05/the-best-rounda...
stormcrowsx 11y ago
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.
hugh4 11y ago
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.
- phire 11y ago
  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.
mixmastamyk 11y ago
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.
- rwmj 11y ago
  The UK also has a lot of roundabouts retrofitted with traffic lights (especially at motorway junctions).
- msandford 11y ago
  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 https://www.youtube.com/watch?v=lwHfibl1AoI
  - mixmastamyk 11y ago
    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.
zb 11y ago
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.
- r0m4n0 11y ago
  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,210.19h,69.12t/data=!3m6!1e1!3m4!1s3yb-E21Li76n8bfNCBpINw!2e0!7i13312!8i6656!6m1!1e1 https://www.google.com/maps/@38.5801855,-121.4694376,3a,75y,...
  - fryguy 11y ago
    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.
  - jotux 11y ago
    Live in Sacramento, the half-roundabouts drive me crazy. Here's another: https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,249.97h,57.49t/data=!3m7!1e1!3m5!1sdd_YkL3XJu7bDNqbRXo4tQ!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3Ddd_YkL3XJu7bDNqbRXo4tQ%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D98.265709%26pitch%3D0!7i13312!8i6656 https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,...
    - ScottRAB 11y ago
      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 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 http://tinyurl.com/bzf7qmg
Sanddancer 11y ago
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.
vermontdevil 11y ago
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?
Someone 11y ago
"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-dutch-roundabout-abroad/ 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.pdf https://www.swov.nl/rapport/Factsheets/UK/FS_Road_fatalities...).
- malandrew 11y ago
  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.
chrismealy 11y ago
Dutch roundabouts are the best. Lots of videos here: https://bicycledutch.wordpress.com/tag/roundabout/ https://bicycledutch.wordpress.com/tag/roundabout/
sremani 11y ago
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.
ck2 11y ago
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.
shocks 11y ago
Here is a particularly terrifying roundabout: https://www.google.co.uk/maps/@51.5628134,-1.7714704,177m/data=!3m1!1e3 https://www.google.co.uk/maps/@51.5628134,-1.7714704,177m/da...
bitwize 11y ago
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.
zkhalique 11y ago
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.
- josu 11y ago
  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.
  - r00fus 11y ago
    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.
malandrew 11y ago
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.
anotherevan 11y ago
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 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.
ctstover 11y ago
I fucking hate roundabouts. There. I feel better now. Thanks. Wait, no the rage is coming back - multi-lanes!!! ahhh!! help!
andrewchambers 11y ago
Why not have a roundabout with traffic lights on the entrances which are turned on at peak times only to ensure even flow.
dynomight 11y ago
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.

49 points by jonathansizz 11y ago

rwmj 11y ago

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-roundabout-design-for-cyclists.html http://www.aviewfromthecyclepath.com/2014/05/the-best-rounda...

stormcrowsx 11y ago

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.

hugh4 11y ago

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.

phire 11y ago
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.

mixmastamyk 11y ago

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.

rwmj 11y ago
The UK also has a lot of roundabouts retrofitted with traffic lights (especially at motorway junctions).
msandford 11y ago
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 https://www.youtube.com/watch?v=lwHfibl1AoI
- mixmastamyk 11y ago
  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.

zb 11y ago

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.

r0m4n0 11y ago
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,210.19h,69.12t/data=!3m6!1e1!3m4!1s3yb-E21Li76n8bfNCBpINw!2e0!7i13312!8i6656!6m1!1e1 https://www.google.com/maps/@38.5801855,-121.4694376,3a,75y,...
- fryguy 11y ago
  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.
- jotux 11y ago
  Live in Sacramento, the half-roundabouts drive me crazy. Here's another: https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,249.97h,57.49t/data=!3m7!1e1!3m5!1sdd_YkL3XJu7bDNqbRXo4tQ!2e0!6s%2F%2Fgeo3.ggpht.com%2Fcbk%3Fpanoid%3Ddd_YkL3XJu7bDNqbRXo4tQ%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D98.265709%26pitch%3D0!7i13312!8i6656 https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,...
  - ScottRAB 11y ago
    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 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 http://tinyurl.com/bzf7qmg

Sanddancer 11y ago

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.

vermontdevil 11y ago

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?

Someone 11y ago

"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-dutch-roundabout-abroad/ 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.pdf https://www.swov.nl/rapport/Factsheets/UK/FS_Road_fatalities...).

malandrew 11y ago
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.

chrismealy 11y ago

Dutch roundabouts are the best. Lots of videos here: https://bicycledutch.wordpress.com/tag/roundabout/ https://bicycledutch.wordpress.com/tag/roundabout/

sremani 11y ago

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.

ck2 11y ago

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.

shocks 11y ago

Here is a particularly terrifying roundabout: https://www.google.co.uk/maps/@51.5628134,-1.7714704,177m/data=!3m1!1e3 https://www.google.co.uk/maps/@51.5628134,-1.7714704,177m/da...

bitwize 11y ago

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.

zkhalique 11y ago

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.

josu 11y ago
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.
- r00fus 11y ago
  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.

malandrew 11y ago

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.

anotherevan 11y ago

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 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.

ctstover 11y ago

I fucking hate roundabouts. There. I feel better now. Thanks. Wait, no the rage is coming back - multi-lanes!!! ahhh!! help!

andrewchambers 11y ago

Why not have a roundabout with traffic lights on the entrances which are turned on at peak times only to ensure even flow.

dynomight 11y ago

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.