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Safety benefits of roundabouts

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Re: Safety benefits of roundabouts

#211

Post by Moru »

peeters wrote: post #169
Enginerrrd wrote: post #107

Earlier quoted context omitted.

Transportation engineer here: Multi-lane roundabouts don't typically have any safety benefits. Single lane roundabouts do. Also, on the small side where you have traffic circles rather than roundabouts, those also suck.

> Multi-lane roundabouts don't typically have any safety benefits. There seems to be quite a bit of literature that flatly disagrees with this statement. Perhaps you could add a source? The conventional wisdom where I'm from is that multilane roundabouts don't reduce the absolute number of crashes (and might even increase crash rates), but they still dramatically reduce the severity of crashes. Canada: > However rece…

The accident rate also goes down with time, people needs to get used to roundabouts.

Re: Safety benefits of roundabouts

#212

Post by Moru »

mitthrowaway2 wrote: post #132
Enginerrrd wrote: post #107

Earlier quoted context omitted.

Transportation engineer here: Multi-lane roundabouts don't typically have any safety benefits. Single lane roundabouts do. Also, on the small side where you have traffic circles rather than roundabouts, those also suck.

While you're here, can I ask you a question I've always wanted to ask about traffic circles? Perhaps this is also related to why they suck for safety. At least where I live, there are two rules for traffic circles: (1) yield to traffic that is already in the traffic circle, and (2) when two cars arrive at the same time, yield to traffic on your right . Rule 1 is the same as for a roundabout, but rule (2) is a bit str…

Sweden treats the roundabouts as it's own road. To get into the circle you yield to whatever is inside the circle. The cars inside the roundabout is on their own road so only yields on lane change from inner to outer lane. When exiting they are leaving the road and is yielding to any pedestrian/bicycle crossing directly after the roundabout. Well, they are supposed to do but mostly don't.

There are a few non-standard roundabouts that has no yield sign and the lane goes straight into the roundabout but then it usually doesn't have an outer lane before that entrance.

Re: Safety benefits of roundabouts

#213

Post by annica »

2muchcoffeeman wrote: post #194
annica wrote: post #192

I could see how these have benefits in some cases. There are also drawbacks… the uncertainty of who is yielding (except maybe by AI). What about snow and ice? If you do some searching there are plenty of reasons why you might not want roundabouts.

> the uncertainty of who is yielding Same we know red light means stop. You make up a rule. In Australia anyone from the right has right of way.

It’s not the same though. Red means stop. It is ambiguous as to who must yield precisely because there is no red light to indicate it. What would the rule be? Your best guess as to the speed and distance of the other driver?

Re: Safety benefits of roundabouts

#214

Post by martijnvds »

LRVNHQ wrote: post #155
michaelteter wrote: post #141

Two lane roundabouts are pretty good. More than two lanes are very questionable. And roundabouts which include... stoplights!?!? are just stupid. I live in the Netherlands, where roundabouts are very common. In many cases, they are an improvement. But NL is also a huge bike country. And at most roundabouts, bikes have right of way. So as a car driver, you have to worry about other cars as well as bikes which may turn…

> But NL is also a huge bike country. And at most roundabouts, bikes have right of way. The fact that it's on a case-by-case basis an not actually a consistent traffic law is really awful. To add insult to injury, the only signage is usually a yield sign painted on the road that is invisible as soon as it's dark and the road is wet. And this is of course further combined with the absolute scandalous amount of cyclist…

It's supposed to be consistent: within built-up areas ("bebouwde kom") bicycles have priority, outside of those areas they don't have priority.

Re: Safety benefits of roundabouts

#215

Post by martijnvds »

ryukafalz wrote: post #179
LRVNHQ wrote: post #155

Earlier quoted context omitted.

> But NL is also a huge bike country. And at most roundabouts, bikes have right of way. The fact that it's on a case-by-case basis an not actually a consistent traffic law is really awful. To add insult to injury, the only signage is usually a yield sign painted on the road that is invisible as soon as it's dark and the road is wet. And this is of course further combined with the absolute scandalous amount of cyclist…

> To add insult to injury, the only signage is usually a yield sign painted on the road Doesn't the red asphalt denoting a cycleway also typically continue across the exits when cyclists have priority?

Generally but not always. The triangle markings on on the ground (like tiny "yield" signs) are a better indicator.

Re: Safety benefits of roundabouts

#216

Post by bobthepanda »

Moru wrote: post #206
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…

Our town has loads of them too, and everyone think they understand them. Still accidents are common because people think it's ok to just go straight through by changing lane to inner and then directly exiting without yielding to the ones crossing their path in the outer lane.

At least in the Netherlands its recommended that the two lane roundabouts have mountable curbs specifically to prevent lane changing.

The US is unfortunately loth to install any sort of divider more than paint or a feeble plastic post, and less than a jersey barrier.

Re: Safety benefits of roundabouts

#217

Post by Moru »

Clamchop wrote: post #151
josephg wrote: post #92

Earlier quoted context omitted.

> because everyone drives incredibly slowly and cautiously since the experience is scary as hell Apparently there are fewer accidents on the roads when the traffic lights aren’t working. The reason is exactly that - everyone is terrified and drives really slowly to make up for it.

I've read that yields can often be safer than stop signs for the same reason.

Just to throw off the statistics: We have a road in town that used to be a straight run through the forest. Suddently it got a yield sign and a bus road crossing it. This ofcourse lead to a number of accidents with cars driving into busses not noticing the yield sign. So next step was stop signs. Still lots of accidents though, since this road has been alone so long and was built for 70 km/h from the start so you don't get any hints about that you should slow down. Then came the thick white lines across the road at regular intervals before the crossing. Still accidents. Now they built some stone divider between the lanes so you have to go a little to the side and can't blow straight through the crossing. I'm just waiting for the speed bumps, that is usually the first stage already, bit confusing that they didn't do that yet.

Re: Safety benefits of roundabouts

#218

Post by Moru »

ajb wrote: post #100
cryptoegorophy wrote: post #46

Earlier quoted context omitted.

How is it even legal? You need a special school just for this one 99lvl king of the roundabouts

You only need to know one fact to navigate it: the middle is not a roundabout, ignore the fact that it is round. Every driver in the UK is used to sequences of two or three roundabouts, they are part of the driving test. As long as you are not bamboozled by the pseudo roundabout in the middle, you just navigate it based on principles you already know.

As a right hand driver since 40 years I can't wrap my head around the combo roundabouts. I get terrified just looking at youtube drivers trying to explain how they work in England.

Re: Safety benefits of roundabouts

#219

Post by dcminter »

KaiserPro wrote: post #41
hristov wrote: post #20

The greatest thing about roundabouts is that they protect against the idiot that goes through an intersection at full speed. He does that either because he is passed out behind the wheel or because he did not notice a stop sign and thought he had the right of way, or maybe because he just does not care. Well with a roundabout if you just go straight ahead you hit the center circle. Good roundabouts always have a slig…

It certainly has some protection: https://www.youtube.com/watch?v=xTk_kPeA63c (turn the sound off, its just road noise) This is what happens when you go full bore into a big roundabout. This kind of roundabout is used to join one large road to one or more small road (think two lanes going from 6-12 on the clock, with single lane road at 3 & 9) In the UK, we don't normally have stop signs, as most junctions have clear…

> we only have one

Actually there's another in Hemel.

Re: Safety benefits of roundabouts

#220

Post by VagabundoP »

Roundabouts work well in my country, mostly, even the three lane ones. However a few weeks ago my wife encountered someone who obviously had a moral objection to the "round" in roundabout and drove in the straight line across three lanes of the traffic to the exit.
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