Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Safety benefits of roundabouts

theconversation.com

Post reply on HN
Print view View original

151–160 of 409 posts

Re: Safety benefits of roundabouts

#151

Post by Clamchop »

josephg wrote: post #92
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.

> 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.

Re: Safety benefits of roundabouts

#152

Post by boxtifer »

tunesmith wrote: post #81

Two-lane roundabouts still confuse me a bit. Even the video tutorial in that article has what looks like a problem to me. At 1:06, the pink car in the right lane skips the first exit. How does the orange car in the left lane know it's safe to take the second exit? That's a collision risk right there if the pink car wants to continue counter-clockwise.

When entering the roundabout, there are two lanes with two different rules.

The right lane is only permitted to turn right or continue straight. So the pink car is not supposed to continue counter-clockwise.

The left lane is only permitted to go straight or turn left. Thus it won't run into the cars on the right lane.

A collision could occur if people don't follow the rules, much like everything else when it comes to driving a car.

Re: Safety benefits of roundabouts

#153

Post by kieranmaine »

swatcoder wrote: post #99
kieranmaine wrote: post #91

Earlier quoted context omitted.

I disagree. As a pedestrian, I only have to worry about cars coming from 2 directions (on to/off the roundabout) instead of 4 at an intersection. I'm confused by your comment that drivers merging into a roundabout are too distracted. As a driver merging into a roundabout I find I have far less cognitive load. I only have to look for pedestrians crossing in front of me and cars coming from the left. When coming off th…

With the exception of decorative 1-lane roundabouts in sleepy residential neighborhoods, all the roundabouts I encounter in Central and Southern California are 2-3 lane circles with various lane->exit mappings, some of which overlap and some of which are exclusive. Drivers coming into them, who want to actually benefit from the roundabout and not just turn it into an awkward stop sign, are responsible for reversing t…

My experience of roundabouts includes single lanes ones in sleepy residential neighbours all the way up to the infamous https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempst....

I'd argue that 1 lane roundabouts are far from decorative in residential neighbourhoods and are safer and allow for a better flow of traffic.

I'm slightly confused by your description, but it sounds like traffic lights for the pedestrian crossings would be a better option (which is often the case with the bigger roundabouts in the UK). Are the roundabouts you referring to like this one https://maps.app.goo.gl/xfxzDWTx4a7WPasUA or smaller?

Re: Safety benefits of roundabouts

#154

Post by hnick »

AmericanChopper wrote: post #122
squarefoot wrote: post #8

Safety aside, roundabouts lower traffic significantly by never forcing cars to stop. Congestion increases as cars need to stop because of the inevitable latency propagating along the tails, and having more than one traditional intersections along the way can only make things even worse, so any solution to prevent cars from slowing down to a stop would mitigate those effects.

They’re often worse in heavy traffic situations. Especially if you have two entrances that feed heavy traffic into the roundabout at peak times, the one that has to yield can end up basically locked out of the flow.

Yes traffic lights can be far better in heavy traffic - at least everyone gets a turn. In some roundabouts I've driven through, where there is a "main" way the cars coming from the other directions often get locked out as people queue through it. It works out if people have some courtesy and take turns but that's not always a good basis for traffic planning.

Re: Safety benefits of roundabouts

#155

Post by LRVNHQ »

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 cyclists who don't have lights at night and are dressed in fully dark clothes.

Roundabouts are already a traffic situation that require heightened attention as a driver, so in the interest of safety I believe crossing cyclists should yield to cars at the exit. It's too many things to worry about otherwise. But at the very least, make it the same everywhere so it's always absolutely clear to both drivers and cyclists who has the priority.

Re: Safety benefits of roundabouts

#156

Post by hnick »

smeej wrote: post #135
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.

I think you're right about single vs. 2+ lanes. It doesn't matter how many diagram signs they put up before the roundabout entry, people will NOT understand a roundabout with more than one lane, and under no circumstance will people going straight through realize they have to yield to someone coming from the opposite side who's going 270° around the circle and exiting from the inner lane. Roundabouts are fine if the…

I don't know what the letter of the law is but I (and most people I've seen here in Australia based on driving patterns) interpret yielding to cars on the roundabout as giving way if I will get in the way. If they're still on the other side of the island, and we can both pass through without getting in each others' way, it's fine.

Of course the de facto standard here (which many people actually think is the law) would be "give way to the right" (i.e. left for US) meaning some people will proceed without stopping even if the car to their direct left got there just before them. I think this is predictable since more risk falls on the driver who is going to get T-boned in their driver side door if they don't stop so they will be naturally cautious.

Re: Safety benefits of roundabouts

#157

Post by InSteady »

citizenkeen wrote: post #149

Portland, Oregon has a roundabout with four stop signs and I've been mad about it for thirty years. Why?!

Because its on a busy intersection and people are idiots. I've used it hundreds if not thousands of times on my bike, not to mention as a pedestrian. I would not do either one if not for the stop signs. I've seen so many idiotic interactions over the years that were only mitigated by the slow speeds starting from a full stop.

People like to zoom down Cesar Chavez especially at night when traffic is light. It would be a death zone for pedestrians and cyclists under normal traffic circle conditions imo.

Also, there are heavily used crossings for two different elementary schools within a few hundred feet of this traffic circle. The impediment to flow of traffic is probably intentional for that reason alone.

Re: Safety benefits of roundabouts

#158

Post by nkozyra »

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…

> And roundabouts which include... stoplights!?!? are just stupid.

I hate these so much. Seems to break the purpose of a roundabout in the first place - to let a single entry and exit pattern dictate the traffic.

Stoplights in them fundamentally break their benefit, which is smooth, one-way flow.

Re: Safety benefits of roundabouts

#159

Post by quickthrower2 »

olyjohn wrote: post #125
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.

Correct me if I'm wrong... but compared to a traffic light, you have to go significantly slower, so most accidents are not as severe as at a traffic light. You also aren't crashing into someone in a t-bone situation, usually they are sideswiped at more of an angle for less impact force. Of course someone could still fly into a roundabout at full speed. Anything is possible, but feel like think overall there still hav…

That is a good point. In the UK when I was last there they needed all sorts of tricks to get people to slow down on roundabouts on A roads or just after a motorway end, going from say 70mph to zero.

You might have a curve leading up to the round about plus roundabout signs, plus give way signs, plus 300, 200, 100 yard markers, plus painted lines on the road that get closer together as you approach, and finally the <<<<< sign on the roundabout itself.

Re: Safety benefits of roundabouts

#160

Post by j16sdiz »

kmeisthax wrote: post #112
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.

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

Depends on which country/state you are from, they may or may not be the same.

Look up on wikiprdia, there are even different types of roundabouts

Post reply on HN