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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

#31

Post by ajmurmann »

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.

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.

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

#33

Post by kazinator »

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 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).

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

#36

Post by eridius »

ajmurmann wrote: post #27
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.

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.

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

#37

Post by jrbancel »

msandford wrote: post #10
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…

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 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.

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

#38

Post by suneilp »

msandford wrote: post #10
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…

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…

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...

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

#40

Post by herbig »

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.…

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.
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