The UK is replacing roundabouts with traffic lights; US is doing the opposite
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Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#2There 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...
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#3I could see roundabouts being an advantage on smaller one or two lane streets but beyond that it seems like it would get dangerous fast.
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#4It'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.
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#5The 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.
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#6I 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.
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#7The 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 traffi…
The UK also has a lot of roundabouts retrofitted with traffic lights (especially at motorway junctions).
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#8The 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.
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#9It'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…
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.
Re: The UK is replacing roundabouts with traffic lights; US is doing the opposite
#10The 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 traffi…
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