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We're excited about our new roundabout

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Re: We're excited about our new roundabout

#311

Post by skeeter2020 »

rob74 wrote: post #260
consp wrote: post #228

Earlier quoted context omitted.

Sometimes roundabouts are used to limit traffic speed, since you MUST slow down, while keeping the same flow (for the calculated traffic throughput). Maybe that was the purpose. Roundabouts are generally more expensive than intersections due to needing more land works and more land than a normal cross intersection.

I don't know if that was the purpose or just a side effect, but I would have thought that the purpose of a bypass is to provide a more attractive route than the one going through the town center (so motorists have an incentive to use it), and having to slow down at the roundabouts (along with the mentioned tight curves and the 60 km/h speed limit) completely destroys the attractivity.

drivers may interpret it differently, but flow is typically faster than stop&go, plus the illusion of "if you're moving you're getting somewhere" helps.

Re: We're excited about our new roundabout

#313

Post by JohnClark1337 »

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…

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Re: We're excited about our new roundabout

#314

Post by desas »

ProllyInfamous wrote: post #289
desas wrote: post #125

Earlier quoted context omitted.

Like the Magic Roundabout in the UK? https://www.bbc.co.uk/news/articles/cdx9nlgk97eo

I would do everything possible to avoid this UK Round-a-bout — nothing Magical about it having three concentric lanes just in its inner loop! =P Ours is much simpler, with a round-a-bout on either side of a regional highway. One of the difficult parts about it is everybody is already jacked the fuck up (on account of 2 of the 5 input/outputs being extremely steep grade to enter/exit a river-crossing, with speeds aver…

Oh, I've re-read and you just mean there are two fast paced roundabouts that are close by and they both have two lanes around them.

That wouldn't raise an eyebrow here in the UK, it's very normal for highway junctions to have on/off ramps that end in 2-3 lane roundabouts, one each side of the highway.

Re: We're excited about our new roundabout

#315

Post by barrkel »

bane wrote: post #288
watwut wrote: post #194

Earlier quoted context omitted.

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

I believe that I've read that elsewhere. They allow for better and higher flow than an intersection, but have a weird failure mode at very high rates where the circle gets loaded and all directions thus stop.

It's rather that if there's a continuous inflow of traffic that usually doesn't take one of the exits, then all traffic coming coming from that exit doesn't get a chance to join the roundabout.

What usually happens is the roundabout gets traffic lights.

Re: We're excited about our new roundabout

#316

Post by PaulRobinson »

rswail wrote: post #151
al_borland wrote: post #87

Earlier quoted context omitted.

I think part of the issue is that it’s multi-lane. So if you’re in the right-lane to go to one road, and miss it, staying in the right-lane forces you onto the highway. If there is a car in the left lane you can’t get over to avoid it without causing an accident, or stopping, which would backup the whole circle and also risk accidents. So you end up paying the 9 mile tax. There is no way to miss your turn and easily…

I like the German roundabouts that have 3 lanes at each entry. The furthest left takes you to the 3rd exit (left hand turn), the middle takes you to the 2nd exit (straight ahead), and the right hand lane takes you the 1st exit (right hand turn). The lanes are painted to "spiral" so that if you take the furthest left hand, by the time you get to the 3rd exit, it's the outermost lane.

Spiral roundabouts are very common all over Europe, including the UK. They take a little getting used to, but once you realise your drivers side wheel just needs to stay the correct side of the white line, and the white line will take you where you need to go, it's all good.
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