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Comment by 015a | Hacker News Reader

You'll notice this quickly in cities with large numbers of roundabouts. Overall and on average traffic is absolutely faster, flows better, and is safer; but in times of high volume you can find yourself in situations where you're sitting at a left turn onto the stretch of road between two roundabouts totally unable to enter traffic because its flowing so smoothly and evenly. Phrased another way, and leaning on some intuition rather than hard data: large deployments of roundabouts seem to very well optimize travel times and safety for 95% of cars, but make the situation much worse for the remaining 5% (not to mention for pedestrians; my intuition as a pedestrian & cyclist in one of these cities is that I'd much, much rather cross signaled intersections when on foot; roundabouts are hyper-optimized for cars and hell for those not in one).

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> but in times of high volume you can find yourself in situations where you're sitting at a left turn onto the stretch of road between two roundabouts totally unable to enter traffic because its flowing so smoothly and evenly.

Go right and then go around the roundabout.

They'll sometimes design that pattern in with "dogbone" style roundabouts where there's a median between the two sides of the street, a roundabout at each end, and you HAVE to go one-way down one side and around the roundabout to turn around. It's quite annoying but probably saves lives.

You don't actually need a median either, you can just have an on-ramp and a yield.

Sure, fine, let me rephrase my issue in a way which changes literally nothing about it but maybe outlines why its still a problem:

I'm sitting at an intersection trying to go left, but with the intention to turn right and 180 around the roundabout; behind someone who also wants to go left but would rather wait for an opening in both directions of traffic.

People are idiotic; traffic systems should, ideally, account for and mitigate this idiocy as much as possible. That's why streets with a impassible divider in the middle exist.

If a wall isn't convincing enough, you can use an on ramp to make it so you can only go right. I think we can move this ticket to OBE

Add another roundabout between the roundabouts. Problem solved!

I have never been in one of these situations. Would it be reasonable to go one roundabout beyond one's turn, use it to reverse directions, and then make a right turn upon returning to the intended turn?

On the walk/bike angle: my vague recollection is that the Not Just Bikes Youtube channel has some recordings of roundabouts that work pretty well for non-drivers, but I can't remember specifics. Maybe just heavy prioritization of those users over drivers.

Yeah left turns like that should be eliminated, or restricted to non-peak traffic times.

You see this with stop signs too: someone trying to turn left downstream of a stop sign on a bigger road gets a neverending set of pulsed cars timed exactly right to just barely confound every opportunity.

Do your roundabouts not have pedestrian crossings? The one in my town usually have bike on-ramps that lead to the pedestrian crossings, and cars will stop if I just stand there with my bike. Or in lower traffic situations I can just ride into and out of the roundabout like a car.

It's a pretty bike friendly town though, so people here watch out. I probably wouldn't try that in a more urban city.

Absolutely, but you end up in weird situations such as with two-lane roads, car in the right lane stops and waits but its not obvious if the incoming car in the left lane will stop, so you can't start walking; or once you make it to the middle (generally with a pedestrian island) having to re-calculate incoming traffic exiting the roundabout, sometimes they'll stop in the dead center of the roundabout and wait for you to cross which is dangerous and idiotic but people do it because they think they're doing a nice thing.

Additionally, you're dealing with the effects that I outlined earlier in the paragraph, but at every single intersection; oftentimes, and especially at intersections where one direction of travel (say North-South) is significantly more popular than the other (e.g. West-East), traffic basically never stops because there's little crossing-traffic to stop drivers from entering the intersection for even a second; and drivers are not required to yield to pedestrians. You start forming prejudices against car brands real quick walking around cities like these ("ope, BMW, no way he'll let me go").

My shadow theory is: people overwhelmingly associate roundabouts as being better for pedestrians because of an unrelated knock-on effect: Cities which invest in roundabouts generally have more money than cities who don't, and cities which have more money are also likely to independently invest in dedicated pedestrian infrastructure, like dividers and rail trails. Roundabouts might be safer for pedestrians, because I'd guess that many pedestrian deaths are the result of cars running red lights, and that's just physically more difficult to do with a roundabout; that's only one component of "better" though, and even then I struggle to find a better data-backed source for that intuition than "some academic or city planner said they're safer for pedestrians".

> Absolutely, but you end up in weird situations such as with two-lane roads, car in the right lane stops and waits but its not obvious if the incoming car in the left lane will stop,

Where I grew up, if a car is stopped in front of a pedestrian crossing, not stopping next to it gets you a pretty hefty fine. Every few years the police have a big public service announcement campaign about it, then focus on giving fines for it in some of the more risky locations.

Roundabouts are better when they are not the multi-lane monsters US tends to build.

Carmel, Indiana is nearly _all_ roundabouts, and pedestrians/cyclists do well relative to other US cities because the crossing distances are short and cars speeds are slower.

https://www.carmel.in.gov/government/departments-services/en...

https://www.iihs.org/topics/roundabouts (ctrl f pedestrian)

I was in London a looong time ago and for some high volume roundabouts (I think they were a little outside of the city) they had stop lights in conjunction with the roundabout to solve this exact problem.

Whatabout roundabouts with pedestrianlights?

I've never seen those before. Does that mean the roundabout has redlights at every entrance

For any roundabout fans on this forum who doubt that roundabouts with stoplights exist, you simply must make a pilgrimage to Washington, DC. They not only have stoplights around their multi-lane traffic circles, they have 3-4 inside some of them! Note the white lines: https://i.imgur.com/4v1c9zB.png

I would argue that isn't a roundabout; its just a road.

A "roundabout" is a kind of intersection. One characteristic intersections generally have is that traffic should not stop upon entering the intersection. The picture you've linked is a circular road, with a half-dozen or so individual signaled intersection along it.

While roundabouts do have center islands, sometimes even with sidewalks, pedestrians generally are not expected to ever walk there. For the same reason as outlined in the previous paragraph: getting pedestrians safely to the center island would require interrupting the flow of traffic inside the intersection. Walking by some roundabouts with built-up center islands, I sometimes wonder how long someone could camp out in the thicket without ever coming within 20 feet of another human on foot; the islands are no-man lands, very unlike the satellite image you link.

I can reasonably envision a pedestrian signaled roundabout, where the crosswalks at the entrances and exits to the roundabout are all signaled. I have not, to my memory, ever seen one. And, again, I think the reality of their rarity speaks to my original point that pedestrians are, as in all US traffic design, always an afterthought.

Despite the circular nature of the roads, the major circles in DC do not function like traffic roundabouts, nor we're they designed with such considerations. On the other hand I suppose most traffic roundabouts don't have parks in the middle.

There are actual roundabouts in DC, but typically they don't have names.

> you simply must make a pilgrimage to Washington

I was in London area in the early 90's and they had stoplights at roundabouts that were high volume. If I remember right, a person told us the lights are only used at certain times of the day.

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