Traffic Circles/Roundabouts?

[3930dave]

3930dave, in australia on roadtrain (2-4 trailers) routes through towns ,they have a raised concrete dome (painted for visibility) so the road trains can drive over it .1st trailer goes round 2nd cuts in 3rd & 4th trailers go over part or all of centre dome. The trailers are 15m long. As long as your engineers learn from australian experiance they should be ok. Lastly remember a truck with a long trailer often needs to turn from the opposite lane, ie turn left from right lane as trailer will cut in to the left lane on smaller roundabouts. If you use the left lane left turn approach you have trailer tracks in the centre lawn/garden,and a lot of mud on the road ,oops.

With a little luck here, the big dual 53' trailers won't see many roundabouts - with our traffic density AFAIK triples or longer aren't allowed in Ontario.

The construction I was thinking of near Toronto was recent renovations to large expressway cloverleaf interchanges - small vehicle traffic volume is so high that it has to be considered re. dual 53'ers being able to merge/maneuver on these major clover leafs.

Rgds, D.

 

[Oaktree]

NH has installed a couple near me now. Their way of keeping it small is to raise the center of the circle with cobble stones. Keeping the 4 wheel cars off but allowing the trucks to ride over the center if needed.

We call 'em rotaries here in New England. For some reason in the 70s & 80s a lot got removed, I'm sure some traffic flow "expert" deemed them inefficient or something. Now they're starting to put them back. They seem to work better than the multi-way stop intersections they went to for a while.

 

[rd_macgregor]

FWIW, this showed up on my news feed today.
Rise of the roundabout: 'Don't be alarmed'

 

[PJSprog]

Ooh ... zombie thread.

There were very few roundabouts in my area until about 5 years ago. Now, they're popping up everywhere like weeds. There's a large one in the center of Belleville, IL that's been there for a long time ... has a large fountain in the middle and everything, very well done. Most of these newer ones, though, are too small and not very well used by the general public. I think most municipalities putting them in are just riding the latest trend. I really don't see these small ones in small towns as any more beneficial than a 4-way stop, and they take up 4-times the space.

The Belleville fountain / roundabout

 

[bcp]

There are more and more around here. What I don't like is that they are all different.

Some have one lane entry, some two lane, and with both one and two lane exits. The right lane may require you to exit at the next street or it may allow you to pass by. Then it may or may not require an exit on the next street. It appears that they tried one each of every combination possible.

Bruce

 

[Sysop]

It's all something to show your tax dollars at waste. They are a way for towns small and large to spend large amounts of money. Fountains, Statues, Flowerbeds, Marble borders and crosswalks; All vast wastes of our tax money in both implementation and maintenance.

 

[CADplans]

We are getting a new one,,, that is specifically designed for mostly 18-wheeler traffic.
It will be used to mesh a major E-W road with two N-S roads, one of which is an interstate.

This will be interesting!!?? :confused2:

It is replacing a 4-way traffic light intersection that sets next to the interstate cloverleaf.
Currently, each of the four entrances to the 4-way intersection gets the green light, on its own.

Miss the light, you might as well shut off your engine waiting for the green light to cycle around,,,

I hope the circle reduces the wait at the intersection,,, :thumbsup:

 

[fidowanttobe]

Getting them here slowly in higher rush hour areas and they are doing very well. Seem to produce a constant even flow as to lights where lots of cars stopped to let one pass. Newspaper polls showed LOTS of apprehension before but have since changed to approval.

 

[downsizingnow48]

One was recently installed along Highway 20 near Upper Lake. This is a fairly rural area. The problem is a few folks think they have the right of way going in. So everyone has to stop or go very slow in the roundabout to make sure they are not going to get rammed by incoming vehicles. Result it is less efficient than the simple T intersection with stop signs that it replaced. At huge cost I am sure it took six months to build.

 

[Egon]

Traffic congestion at the roundabout.

[video]https://www.google.ca/search?q=paris+roundabout&client=safari&hl=en-ca&prmd=inmv&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi79rvv3drPAhVkyoMKHcrGD8oQ_AUIBygB&biw=1024&bih=681#imgrc=uYA7IVRoDNrbEM%3A[/video]

The interchange solution.

Siberian Rush Hour.

[video]https://www.google.ca/search?q=siberian+roads&client=safari&hl=en-ca&prmd=vimn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjNnNyw5NrPAhWhx4MKHRbqDJcQ_AUICCgC&biw=1024&bih=681#imgrc=fXpK94qUcQ_NFM%3A[/video]

Downunder Rush Hour.

https://imgur.com/oT6UMli

 

[k0ua]

What do you guys think of the Diverging Diamond overpasses. We are getting more and more of them here in Branson, and Springfield.

 

[prichard]

In FL they went to something similar to the diverging diamond where both exit ramps or on ramps can flow at the same time. Very efficient.

Around here there are lots of new roundabouts replacing 4 way stops. These seem to keep traffic flowing much better than the 4 way stops did.


Edit this is what I saw in FL: Single-point urban interchange - Wikipedia

 

[bigtiller]

I have been on a few of them and most of them seem to small. It seams a pick-up truck pulling a 16' trailer would use up his lane and a lot of the other lain.

 

[turnkey4099]

One was recently installed along Highway 20 near Upper Lake. This is a fairly rural area. The problem is a few folks think they have the right of way going in. So everyone has to stop or go very slow in the roundabout to make sure they are not going to get rammed by incoming vehicles. Result it is less efficient than the simple T intersection with stop signs that it replaced. At huge cost I am sure it took six months to build.

Wait until people are used to it and you will find traffic movign very smoothly.

 

[turnkey4099]

I have been on a few of them and most of them seem to small. It seams a pick-up truck pulling a 16' trailer would use up his lane and a lot of the other lain.

Not unusual to see at least the pup wheels going right over the hump in the middle.

 

[3930dave]

Not unusual to see at least the pup wheels going right over the hump in the middle.

No curb on the hump - no harm/no foul - a reasonable trade-off vs. making the circle much larger.

Once people get used to them, traffic flows well. Out in farm country, where traffic is normally light - you can (legally) keep rolling through what used to be a 4 way stop - really nice, esp. when pulling something.

Things get maxed out eventually; once traffic gets heavy enough, the flow gains from circles may not be there.

Rgds, D.

 

[aczlan]

They put in a pair of roundabouts near the county fair grounds (which also hosts a dirt racetrack).
They have one paved lane and then a sloped curb and an inner "lane" that is made of stamped, colored concrete (so it looks like bricks).
It is about the same for light traffic, but much better with medium to heavy traffic. When it gets swamped, its a pain, but its still better than the previous 4 way stop.

 

[QRTRHRS]

Now that everyone has expounded on the traffic circles, try on the "crossover intersection". (Do a search) They work where there is not enough room for a true cloverleaf but o'wow', the first time through is a treat. There is one in Lexington, KY, RT 4 and Harroldsburg Road. Having been through it a couple of dozen times or so, I still get a kick out of it.

 

[2ndhalf]

Now that everyone has expounded on the traffic circles, try on the "crossover intersection". (Do a search) They work where there is not enough room for a true cloverleaf but o'wow', the first time through is a treat. There is one in Lexington, KY, RT 4 and Harroldsburg Road. Having been through it a couple of dozen times or so, I still get a kick out of it.

I think I went through one of those around San Antonio. I googled it and it looked like the image that came up. Your right they are a little trippy at first.

 

[2ndhalf]

I have been on a few of them and most of them seem to small. It seams a pick-up truck pulling a 16' trailer would use up his lane and a lot of the other lain.

Oh well... "When your in it you own it"... as I heard stated!