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Safety benefits of roundabouts

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Re: Safety benefits of roundabouts

#391

Post by peeters »

RHSeeger wrote: post #222
yreg wrote: post #140

Earlier quoted context omitted.

> people will NOT understand a roundabout with more than one lane We have tons of 2-lane ones and everyone understands them…

Honestly, even looking at a picture showing how a 2-lane roundabout works ( https://www.epermittest.com/drivers-education/roundabouts ), I still can't understand how it works. Assuming 0 is the bottom and 90 is the right, how is it that a person following the inside route from 0 (exiting the left lane at 180) isn't going to get hit by someone following the outside route from 90 (exiting the right lane at 270)? I woul…

> Assuming 0 is the bottom and 90 is the right, how is it that a person following the inside route from 0 (exiting the left lane at 180) isn't going to get hit by someone following the outside route from 90 (exiting the right lane at 270)?

The person following the outside route from 90 must yield before even entering. It's very confusing until you're actually in them, but they're small enough that what you're saying usually isn't really a problem (at least in well designed roundabouts). When the car at 90 enters the roundabout intending to take the 270 exit, they yield to traffic in ALL lanes that might be exiting. Not just traffic in the outer lane. If they were intending to take the 180 exit, they only need to worry about traffic in the outer lane (or people incorrectly changing lanes when exiting).

Re: Safety benefits of roundabouts

#392

Post by peeters »

dublinben wrote: post #193
peeters wrote: post #173

Earlier quoted context omitted.

Not sure exactly what you mean by freely, but in most popular roundabout designs you can exit from the inner lane. A "standard" two lane roundabout will have two lanes entering AND exiting. You never change lanes in roundabouts, at least where I'm from. Only in a massive multi-lane roundabout (that's at that point more like a ring road) would you ever change lanes to exit. e.g. for a standard two lane roundabout with…

The car from the inner lane swiping into the car in the outer lane is the exact issue I'm talking about. The problem is when drivers enter in the left/inner lane, fully intending to take the first exit. If they proceed to exit directly from the inner lane, without first changing lanes, signalling, or yielding to outer traffic, they would intersect with a car in the outer lane innocently heading to the second exit. In…

> The problem is when drivers enter in the left/inner lane, fully intending to take the first exit. If they proceed to exit directly from the inner lane, without first changing lanes, signalling, or yielding to outer traffic

Yes, in that case a driver not understanding the rules of the road (that you can't take the first exit from the inner lane, which is usually clearly signed) could cause an accident. The exact same way turning right from the left lane in a signalized intersection can cause an accident. The question is, what's the damage of an ignorant driver and how fast do people learn? The research indicates that right-of-way incursions in a roundabout result in dramatically fewer injuries than right-of-way incursions at other types of intersections, and the research also indicates that contrary to your belief, drivers actually do learn how to use them.

Re: Safety benefits of roundabouts

#393

Post by VincentEvans »

rwmj wrote: post #11

If you like roundabouts, try a roundabout of roundabouts: https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempst... This is near where I live and it is indeed safe, mainly because everyone drives incredibly slowly and cautiously since the experience is scary as hell.

I’ve always thought that the safety effect of the roundabouts - is not anything related to it’s traffic flow properties, but rather the fact that roundabouts are confusing and people slow down and proceed with caution.

We could accomplish the same with other forms of creative driver-hostile road construction and deliberately unproductive signage.

Re: Safety benefits of roundabouts

#394

Post by datavirtue »

bheadmaster wrote: post #340
datavirtue wrote: post #330

Earlier quoted context omitted.

Adorable. Where I live people stop in the roundabout when they see other cars coming or they stop at the roundabout if they see any car approaching. People just don't get it.

Well, I don't know where you live, but where I live, if you're entering the roundabout, and cause an accident by not yielding to the person who's already inside the roundabout, it's entirely your fault and you (or your insurance) pay the damages. So anyone who's inside the roundabout can be pretty sure that nobody will slide in in front of them.

And yet they keep stopping...don't know what to say

Re: Safety benefits of roundabouts

#395

Post by kmeisthax »

pests wrote: post #174
kmeisthax wrote: post #112

Earlier quoted context omitted.

wait I thought "traffic circle" and "roundabout" were synonyms

This is the first time I've even heard the term "traffic circle"

It's an Americanism. "Roundabout" is the God Given Queens[0] English equivalent.

[0] King Charles is so uncharismatic I do not acknowledge his existence

Re: Safety benefits of roundabouts

#396

Post by yreg »

JohnFen wrote: post #386
yreg wrote: post #339

Earlier quoted context omitted.

Bratislava, Slovakia. I don’t recall anyone I know having an accident on a roundabout. Newbie drivers I talk to/drive with are much more worried/unsure about crossings (both the ones without traffic lights and the big ones with many lanes) and of course about parking. Of course, there will be SOME people who are clueless on roundabouts, similar to how there are always some people who will stop on a highway after miss…

> there are always some people who will stop on a highway after missing an exit and pull back. What?? People do that?? My mind is blown. I've never once seen that happen, so the possibility never entered my mind. Now that I think about it, though, I should probably be more surprised that I haven't encountered it.

Some people drive crazy

https://youtu.be/r86kxxU-LUY

Re: Safety benefits of roundabouts

#397

Post by pests »

kmeisthax wrote: post #395
pests wrote: post #174

Earlier quoted context omitted.

This is the first time I've even heard the term "traffic circle"

It's an Americanism. "Roundabout" is the God Given Queens[0] English equivalent. [0] King Charles is so uncharismatic I do not acknowledge his existence

I am American! Metro Detroit area. I guess we also don't have many roundabouts. A lot of our road designs are based on Michigan Lefts[0] though which Wikipedia says are also called "median U‑turn crossover or median U‑turn, or restricted crossing U-turn (RCUT)" which I don't see much elsewhere in the country.

[0] https://en.wikipedia.org/wiki/Michigan_left

Re: Safety benefits of roundabouts

#398

Post by fy20 »

devnull3 wrote: post #78
throw0101a wrote: post #74

Earlier quoted context omitted.

"Spiral Roundabouts | Understanding what to do": * https://www.youtube.com/watch?v=e6TsX9Ob91w I'm more curious about the straight-through path of [1] above.

There is a sign board which tells whether to take the middle road or left [1] This is the round-about layout [2] None of the above tell the precise lane to take. Only when you enter the roundabout you will know. See.[3]. Imagine cars waiting on these markings. This is what frustrates me the most. [1] https://www.google.com/maps/@51.5066257,-0.5789164,3a,75y,32... [2] https://www.google.com/maps/@51.506316,-0.5784722,…

My city has a lot of large roundabouts and a few years ago they made big improvements that reduced the number of incidents and improved traffic flow:

1. They switched from 3 lane traditional to 2 lane spiral roundabouts. There are signs well before you enter the roundabout telling you what lane you need to be in, so you can get into the right lane early. We have a lot of snow in winter, so road markings are not visible.

Example of a sign indicating which lane you need to be in. After this sign, there are two more signs indicating lanes before you get to the roundabout - the next has destination names.

https://maps.app.goo.gl/zJLaFC78i232mUkh6

2. The lanes on the roundabouts have solid white lines which you must not cross. You can only cross lanes to go more towards the center. I'm surprised, but people actually follow this rule.

Example of lanes (and a rare sight of police...)

https://maps.app.goo.gl/HbnkXYkacX3dfq4j6

3. They added speed bumps on the roundabout. This slows down the traffic on the roundabout, giving more chance for vehicles to enter.

https://maps.app.goo.gl/fMKBjocYAFTmpE6ZA

Re: Safety benefits of roundabouts

#399

Post by sfn42 »

peeters wrote: post #390
sfn42 wrote: post #259

Earlier quoted context omitted.

The part you're missing is you have to yield when changing lanes, just like in any other road. If you are in the inner lane and you want to exit, you have to make sure the coast is clear. In other words, you are responsible for not getting hit. If you just blindly change lanes you might get crashed into and that would be your fault.

> The part you're missing is you have to yield when changing lanes, just like in any other road. This is not true with most roundabouts in North America at least. If you look at the diagram GP posted, you do not change to the outer lane to exit. You exit directly from the inner lane. In fact, you NEVER change lanes in a roundabout. The reason this works (where the inside lane crosses the outside) is because the round…

That doesn't work. If I enter a 4-way roundabout going left, I will start off in the left lane. I will pass two exits and leave through the third. When I exit, someone from the second exit could be in the lane next to me, going to the road I came from. I have to yield.

When you exit from the inner lane you necessarily have to change lanes because the inner lane is completely inside the outer lane. You may not think of it as a lane change because you're going across the lane not merging into it, but it is a lane change and you have to pay attention.

Re: Safety benefits of roundabouts

#400

Post by DrScientist »

Big fan of roundabouts - generally they keep the traffic flowing much better than lights and work well for cars.

However if I'm on a bicycle, or I'm a pedestrian trying to cross the road near them, they can be more dangerous.

There is a special kind of roundabout that is designed to tackle this issue - the so called dutch roundabout ( at least in the UK :-) ) however it does require drivers to know how it works - so there is always a chicken and egg problem as you introduce them.

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