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

We're excited about our new roundabout

wsdotblog.blogspot.com

Post reply on HN
Print view View original

211–220 of 316 posts

Re: We're excited about our new roundabout

#211

Post by ndsipa_pomu »

maltalex wrote: post #88
woleium wrote: post #77

Earlier quoted context omitted.

In the UK they are called mini roundabouts, and are sometimes just painted on: https://commons.m.wikimedia.org/wiki/File:Mini-roundabout.jp...

Painted roundabouts will be invisible when it snows.

I'm not sure what your point is as roads become invisible when it snows. Is there something unique about a mini roundabout versus any other road markings? It's almost as though you're implying that drivers will speed towards a multi-road junction when it's snowing and not bother to slow down, despite the signage.

Re: We're excited about our new roundabout

#212

Post by ColinWright »

shiroiushi wrote: post #161
lmm wrote: post #100

Earlier quoted context omitted.

They absolutely are. Even if they don't prevent all collisions, they turn T-bones into glancing hits and so save a lot of lives. The worst roundabout beats the best 4-way stop any day of the week. Sometimes there really are easy answers.

>Even if they don't prevent all collisions, they turn T-bones into glancing hits No, they don't, at least not in America. When you let American traffic engineers design a roundabout, you get this: https://www.google.com/maps/@38.8643875,-77.2755474,583m/

As others have said ... that's not a roundabout.

Here's one of my favourite hybrid "roundabout" junctions:

https://www.openstreetmap.org/search?query=Boughton%20Heath%...

Re: We're excited about our new roundabout

#213

Post by fransje26 »

Plasmoid2000ad wrote: post #170
fransje26 wrote: post #154

Earlier quoted context omitted.

As the credited inventors of the modern roundabout, I've always wondered how the UK traffic planners managed to misunderstand their own creation to the point that they come up with such designs.. An other baffling design I've encountered in the UK is a roundabout with traffic lights half-way through.. Wasn't the concept based on removing traffic lights to fluidify traffic..? As a whole, if designers come up with far-…

Roundabouts with traffic lights are a bit of a failure alright - and the larger ones are i'd argue not roundabouts at all - they just share the shape. I believe traffic lights are always trying to solve a capacity issue - where the roundabout has hit it's maximum capacity and is suffering some throughput issue, which tend to sort of get exponentially worse. With traffic light sequencing, particularily dynamically, th…

> Slowing down is important though, as it give drivers time to think and react. Whether they choose to use that time correctly is a problem, but hopefully some or all of the other drivers can use patience and avoid an accident.

I fully agree, and I also think that the "original" roundabout design serves that purpose well, although throughput might different than with dynamic traffic lights.

The point I was trying to make was that slowing down traffic through added complexity could be a dangerous approach to take. It's a switch from a low cognitive load approach by simple design -slow down to a stop/almost stop, look to one side, give way if necessary-, to a slow down of higher cognitive load -slow down, figure out how to navigate a more complex (new) intersection, and maybe remember to give way-. So where in the first approach cognitive load is used to assess how to give way, in the second approach some of that load is used to deal with a more complex/unfamiliar situation. And for some users, I argue, that could already push them more towards accident territory as less cognitive capacity is available to properly assess the traffic situation. Sometimes less is more.

Re: We're excited about our new roundabout

#214

Post by cameronh90 »

lmm wrote: post #100
bnralt wrote: post #95

Earlier quoted context omitted.

Online I see this mentality that roundabouts are great no matter what and it seems really strange to me. It really depends on the design of the roundabout and the traffic conditions. Where I grew up there are a lot of roundabouts, but many of them are so dangerously designed I started actively avoiding them. It’s not that you can’t poorly design a four way stop, but it seems to be much less common, for whatever reaso…

They absolutely are. Even if they don't prevent all collisions, they turn T-bones into glancing hits and so save a lot of lives. The worst roundabout beats the best 4-way stop any day of the week. Sometimes there really are easy answers.

Roundabouts not good for pedestrians and cyclists. In London we’ve been replacing roundabouts with other types of junction to improve pedestrian and cyclist safety.

We don’t have four way stops though so instead it’ll be min/maj junction or traffic lights.

Re: We're excited about our new roundabout

#215

Post by jnovacho »

watwut wrote: post #194
bane wrote: post #108

This is oddly timely. I'm travelling in Europe at the moment and have been covering a lot of area with a lot of roundabouts where they would be signaled or signed intersections in the US. They definitely make traffic flow smoothly and I've noticed a few areas where they are used to eliminate dangerous left turns at places like parking lots, you leave turning right, hit the next roundabout to "uturn" then head back th…

> They definitely make traffic flow smoothly They make slow or medium traffic flow smoothly. If the traffic is heavy, roundabouts make everything worst.

Yep, in my city we have a roundabout with 4 cardinal directions, roughly aligned with compass directions.

The West connection is to/from highway, so it has most traffic. People arriving from North/East/South want to leave on the West. And this causes massive jams, as the constant supply of traffic going from South entry to the West exit (i.e. doing left turn, and passing all ramps) essentially blocks all the other traffic.

Roundabout are great, they increase safety of dangerous intersections. But sometimes a controlled intersection is just a better idea.

Re: We're excited about our new roundabout

#216

Post by moffkalast »

alt227 wrote: post #164
jen729w wrote: post #157

Earlier quoted context omitted.

Similarly this is a mandatory mention. https://en.wikipedia.org/wiki/Magic_Roundabout_(Hemel_Hempst...

Oh come on the Swindon one is the original and best :) https://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

> In 2009, it was voted the fourth-scariest junction in Britain

Only fourth? Pssh!

Re: We're excited about our new roundabout

#217

Post by USiBqidmOOkAqRb »

bnralt wrote: post #158
Arn_Thor wrote: post #129

Earlier quoted context omitted.

I'd really like to know where this was or see some pictures of it. It's almost inconcievable that something designed like a roundabout would be more dangerous. It might indeed cause more accidents due to the kind of confusion you describe, but at the very least the angles and grading should lower speeds dramatically and result in fewer deadly accidents.

It's set up like this - busy avenue with lanes (left to right) 1, 2, and 3 enter into roundabout with circles (inner to outer) A, B, and C. The problem is that half way around the circle, where the avenue continues, A, B, and C then have lines indicating that you can either continue on the circle or move in a perpendicular direction to the circle and exit back such like this A -> 1, B -> 2, and C -> 3. And that's wha…

PIT maneuver is not a T-bone. Even if you cut across a lane (from C to A) there won't be enough of lateral velocity to make it potentially deadly. That's one the of the major points of roundabouts.

Re: We're excited about our new roundabout

#218

Post by Filligree »

Ekaros wrote: post #184
talideon wrote: post #144

Earlier quoted context omitted.

The right solution would've been to remove all the stops. They defeat almost the whole purpose of the roundabout.

I thought the standard for roundabouts is yield sings on all entrances. Not stops, just simple yields...

Yields, yes.

Re: We're excited about our new roundabout

#219

Post by rjmunro »

Ekaros wrote: post #184
talideon wrote: post #144

Earlier quoted context omitted.

The right solution would've been to remove all the stops. They defeat almost the whole purpose of the roundabout.

I thought the standard for roundabouts is yield sings on all entrances. Not stops, just simple yields...

This. If it's not the case that all entrances have a Yeild (what we call "Give Way" in the UK), it's not a normal roundabout.

The feature that seemed to be missing from the roundabout in the original post was any kind of signage. Normally in the UK, roundabouts have a sort of map view as you approach them, then on the islands are signs telling you where to exit.

Re: We're excited about our new roundabout

#220

Post by rjmunro »

WillPostForFood wrote: post #109
lmm wrote: post #100

Earlier quoted context omitted.

They absolutely are. Even if they don't prevent all collisions, they turn T-bones into glancing hits and so save a lot of lives. The worst roundabout beats the best 4-way stop any day of the week. Sometimes there really are easy answers.

No easy answers, no solutions only trade-offs. Perhaps better for safety, but they makes crossing as a pedestrian longer and harder. And while intersections designed for roundabouts can be pretty smooth, retrofitting undersized roundabouts into intersections designed a 4-way makes for ugly and difficult to navigate messes. I like them, but it is a mistake to blindly install them anywhere possible.

In most of the world, unless the intersection has pedestrian features (like traffic lights with green men or islands with pedestrian waiting areas), it's better to cross the road away from the intersections. Then you only have 2 directions of traffic to worry about. AFAICT, in the US, crossing away from the intersections is illegal in many cases.

When Cycling and approaching a roundabout move to the middle of the lane and follow the same routes as a car. Yes you slow the cars a bit but they are supposed to be going slowly anyway. If you don't want to do that, you can get off your bike and cross as a pedestrian would.

Post reply on HN