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

theguardian.com

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

#41

Post by fryguy »

duaneb wrote: post #26
verelo wrote: post #21

Earlier quoted context omitted.

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 lo…

> 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.

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.

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

#42

Post by mikestew »

kazinator wrote: post #33
zb wrote: post #6

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 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.

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

#43

Post by mmanfrin »

r0m4n0 wrote: post #11
zb wrote: post #6

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.

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,...

That's not a roundabout. That is a 2-way stop with a speed-abatement island.

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

#44

Post by zkhalique »

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.

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

#45

Post by msandford »

jrbancel wrote: post #37
msandford wrote: post #10

Earlier quoted context omitted.

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 p…

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…

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.

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

#46

Post by Nadya »

herbig wrote: post #40
kazinator wrote: post #33

Earlier quoted context omitted.

> 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.…

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.

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

#47

Post by function_seven »

fryguy wrote: post #28
function_seven wrote: post #17

Earlier quoted context omitted.

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.

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

#48

Post by malandrew »

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.

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

#49

Post by kazinator »

herbig wrote: post #40
kazinator wrote: post #33

Earlier quoted context omitted.

> 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.…

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.

West coast Canada. (See mikestew's sibling comment to yours).

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

#50

Post by toast0 »

mixmastamyk wrote: post #5

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 traffi…

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.
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