The UK is replacing roundabouts with traffic lights; US is doing the opposite
theguardian.com
theguardian.com
https://www.google.com/maps/@38.5801855,-121.4694376,3a,75y,...
https://www.google.com/maps/@38.6759386,-121.5367581,3a,90y,...
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,...
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.
Maybe outside of cities. In cities, they are the best thing ever for pedestrians.
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.
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.
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.
https://www.google.com/maps/place/Washington,+DC/@38.9092507...
https://www.google.com/maps/place/Washington,+DC/@38.9020455...
I just checked via Google street view and it confirms my memory.
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.
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.
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($), whereas the inconvenienced/threatened party is given the right to several prolonged honks of the horn.
5. Where visibility over the other converging roads is not obstructed by building, bush or otherwise, the four-way stop may be completely ignored when not approached by another vehicle with an estimated arrival time that is within a second, either way, of one's own arrival time. (Pedestrians and cyclists may optionally be counted as vehicles at the driver's discretion.)
Who needs roundabouts?
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$. The governing principle here is consistency -- with rule (2).
(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.
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 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.
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.
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
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.
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.
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.
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 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...).
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.
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.
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.
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?
There should be a compass marking at the center of each roundabout as standard.
There. I feel better now. Thanks.
Wait, no the rage is coming back - multi-lanes!!! ahhh!! help!