Safer roundabouts are replacing traffic signals (2023)

I'm an American who lived in the UK for a couple of years. They have many roundabouts there, and I love them. But now I live in an American town with a few, and I've realized that there's a reason that they are less safe in the US than in the UK--besides the fact that American drivers are less familiar with them. It's a solvable problem, but not one I've heard people talk about. (Though to be clear, I'm not a traffic engineer.)

Most American drivers are familiar with slip lanes, which allow drivers to make a right-hand turns without necessarily coming to a stop. (Wikipedia article: https://en.wikipedia.org/wiki/Slip_lane. Note that the diagram shows an example from a country where they drive on the left side of the road.) They're convenient for drivers, but dangerous for anyone on foot or a bike. This is because a driver in a slip lane is looking for an opening in traffic in the direction opposite of the direction they're traveling.

A roundabout is basically an intersection made up of nothing but slip lanes. So they're fundamentally dangerous to pedestrians in the same way that a slip lane is, but the fact that vehicles are moving slower means that they're still safer than typical American intersections.

However, if I remember correctly (it's been over 20 years ago), in the UK they don't mix roundabouts and crosswalks. They'd put crosswalks (called "Zebra crossings": https://en.wikipedia.org/wiki/Zebra_crossing) between intersections, where drivers aren't distracted by other things. I think we need to do that in the US as well if we're going to adopt roundabouts.

Anecdotally, I also think the way roundabouts get built in the US is better now than a decade or two ago. It used to be that roundabouts (being unfamiliar) were just treated as a cookie-cutter object to plunk into the roadspace blindly.

Nowadays I often see the designers making conscious decisions like:

* what radius?

* what angle do we need so it doesn't even make sense to try to turn left?

* hard curb or drivable curb?

* central pit, flat center, or raised center?

* full roundabout, or teardrop-shaped (common on both sides of a highway bridge)? Apparently peanut-shaped is also a possibility though I haven't seen one.

* one-lane, two-lane, or a mixture (potentially including partial three-lane) depending on what part of the circle (common when there's a "major" road meeting a minor one)?

This is all of course ignoring the fact that drivers are also more aware of how to use them nowadays.

I spend a lot of time near Manchester, VT where there are a handful of roundabouts including two in quick succession, one of which is as small as it is busy. The problem, based on my observations, is that many Americans have no idea how to use roundabout, nor how to signal through them. I feel unsafe every time I'm in the roundabout and have nearly been T-boned multiple times by people feeling they have the right to enter the roundabout regardless of existing motorists already being there. The Yield sign before the roundabout is ignored.

In rural America, there are super dangerous 4-way intersections with stop signs. We're talking highways with 55+ MPH (~88 KPH) speed limits that are relying on everyone to see the sign and stop. Roundabouts would be much safer and better for traffic flow.

There was a recent event where the interstate was closed (accident or something) and everyone had to re-route on those highways resulting in chaos at those intersections.

Trying to explain how roundabouts work to someone who doesn't get them is extremely frustrating. The rules are simple, but for some reason a lot of folks are vastly overthinking it.

The thing is, I like roundabouts, but I'm somehow not surprised that the metrics focus on accidents involving death or injury. I think that because people have to slow down, it must improve those metrics. But there's a particular glut of bone-headed people who power right into the roundabout without anything resembling yielding, to the point where I would legitimately not be surprised if there were actually more accidents overall. That may still be better, but it's incredibly frustrating how badly people handle roundabouts given their simplicity.

Most people who object to roundabouts are drivers who don't know how to drive on them, which leads to hand-wavy dismissals of all criticisms of roundabouts as "you'll learn, look at these stats, they're safer!"

But for a pedestrian in a populated area, roundabouts are not an improvement.

Quick, how does a pedestrian safely cross a lane of traffic? Is it while dodging moving traffic, or does it involve traffic coming to a stop?

If you said the first, I hereby revoke your license to design public infrastructure. For pedestrians to safely cross a lane of traffic, cars need to come a stop, period.

And the whole selling point of a roundabout is that cars don't come to a stop. This is fine for rural areas or large interchanges. But for anywhere that pedestrians are expected to be, roundabouts make the environment more hostile.

And this is before we consider that to cross a roundabout requires setting the pedestrian crossings back from the intersection, forcing pedestrians to zig-zag in order to use them.

And this is also before we consider that we know for a fact that shallower turns (which allow cars to retain more speed) are less safe than sharper turns (which require cars to shed speed), which further exacerbates the pedestrian safety issue.

To say nothing of the fact that roundabouts preclude implementing pedestrian scrambles, which are the safest and most efficient form of pedestrian crossing.

Roundabouts are a solution to a problem of making roads safer for cars, at the expense of pedestrians and cyclists. They exacerbate the problem of our depressingly car-oriented infrastructure. "But the stats say they're safer!" Yeah, and when Google reduced page sizes they saw their average latencies increase. This is a fun way of lying with statistics. Sure, fatalities from roundabouts go down when you create such a human-hostile environment that every pedestrian and cyclist goes out of their way to avoid it, or just throws their hands up in despair and buys a car, since it's a signal that car owners are the only thing people worth optimizing for.

Having looked at some of the links in the article, I just realized that one extra feature of roundabouts is that they allow U-turns (which is not always the case at an intersection).

"As a person with a vehicle built within the past 15 years with massive A-pillars, I don't like them."

I'm actually fond of rotaries in general. But especially for newer smaller ones, it feels like the gradual turning of your path is much worse for keeping a walking pedestrian within your recently-created front blind spot as you're merging in, just when your attention is focused on other cars. I counter by bobbing my head left and right to see around the post, but I don't think most drivers do this.

I obviously can't argue with the statistics, but I also have to wonder if they're telling the whole story.

No HN discussion of roundabouts is complete until someone has posted the Magic Roundabout. There are several in the UK, this is the one nearest to me. And yes it's as insane to drive on as it looks, but safer as everyone is terrified and drives slowly. https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempst...

When cycling or walking, I find roundabouts less safe and more inconvenient than traffic lights. Especially the multi-lane variety.

Road Guy Rob did a video a little while ago, "Let's FIX the HIGH SCHOOL... with 152 ROUNDABOUTS!":

> When the bell rings at Carmel High School, parents race in from all directions to create a zoo of cars, students, and tired teachers all try to use the road at the same time. How a city's failed attempt to build two roundabouts to fix the problem led to an addition.

* https://www.youtube.com/watch?v=1ZUZA76L09M

Related, "Roads don't have to be FAT to be FAST":

> Red lights ruin perfectly good highways and make them grow wider than they really need to be. How a town got a highway moving fast again without adding a single new lane.

* https://www.youtube.com/watch?v=UV0x2hNRYnU

I live in a country where roundabouts are common. They're great for relatively low traffic intersections as you can often get through much faster than lights.

They are a liability when traffic levels are high enough - say during peak times - when one inbound direction is blocked by another.

Wondering why Americans loathe them?

Roundabouts are great, if they are single-lane, low speed, and have great visibility for every exit direction.

As soon as you overcomplicate it, like adding lanes, lights, 5+ exits at different angles, I would bet the advantages mostly disappear.

I like single lane roundabouts.

Multi-lane roundabouts, though, freak me out when they're really tight, have a lot of lanes or don't have lane markers (e.g. Place Charles de Gaulle in Paris).

I didn't get from the article: are they better than all traffic signals, or signals with unprotected left turns? And what's a good vs. bad turnabout like?

I have had to go through a few that feel extremely dangerous compared to having all cars stop for me. So I know I must be missing something.

Edit: Also, I see a lot of comments on yield. I'm probably confused too, but how do they work when traffic is non-stop? Is there a specific traffic rate beyond which roundabouts become less safe?

Carmel, Indiana has over 150 roundabouts and they are building more. I believe we have less than 5 traffic light intersections now but I'm not 100% sure.

The movement around Carmel is remarkable compared to driving next cities (Indy, Fishers, etc). Fishers and Westfield are building more roundabouts as well.

As for one person who commented about high traffic locations - Carmel would make an overpass for those intersections though they are not many.

Exactly the same was true in 1970. Yet 50 years on, and nobody really cares.

It's always someone else's daughter who will be killed in a car accident.

As an American, I don’t see a ton of these - but they are absolutely more efficient at intersections without a ton of traffic. The length of red lights can be ridiculous in places where you just sit and wait with no traffic.

I'll like roundabouts as soon as someone comes up with a good way to fix the resource starvation problem (i.e., if there's a constant stream of traffic from your left, you'll never get a turn to go).

(2023)

Convincing an American that roundabouts are good is about the same conversation as convincing an American to give up their gun.

Some will 'get it', most will not.