Roundabouts are fine for light to maybe even moderate traffic. But heavy traffic they are a night-mare
I friend of mine was a Lt in the Chelmsford MA police department during the time they turned the Drum Hill Rotary into the Drum Hill square with lights at each of the corners. Traffic accidents went from over 350/yr down to 5/yr. MA in general is set to eliminate these traffic nightmares.
http://archive.boston.com/news/local/articles/2004/03/27/mass_drives_to_remove_rotaries/
The rotaries referred to in that article from 2004 were already very old. I remember seeing such in the early 1970s on some early trips east. They were disconcerting to a 20-ish midwesterner.
Newly designed rotaries take up a lot more space and handle a lot more traffic volume than the old timers. Like newer cars, they have a lot more safety engineered into them. We will get used to them.
A year or two after high school graduation, a very sweet girl in my class and her friend were killed at a T intersection of a county road with US 10, both 2-lane roads then. I have thought of her for decades when near that intersection.
US 10 there is now 4-lane. Recently a rotary was constructed there. The likelihood of a fatal crash there is now almost zero.
What I am not fond of is how many busy four lane streets in the St. Louis metro area have a fifth âsuicideâ left turn lane the entire length of the road. It may make it convenient for left turns without circling around but there are plenty of accidents and head-on collisions.
Howâd I miss this when first posted @Cavell? I know exactly where that is. Right near Omni Brewing.
Minnesota traffic engineersâ love affair with roundabouts is almost as bewildering as their earlier love affair with cloverleaf intersections on freeways. I guess weâve improved because roundabouts arenât automatically dangerous like cloverleafs?
At least this one is fairly shallow. Theyâve got a couple of tight roundabouts in Cottage Grove right near a bunch of stores, and when semis deliver goods there they have a hell of a time with the radius. Dumb.
At least that one makes a little bit of sense from a traffic flow perspective. The one I really donât get is just east, at the entrance to Elm Creek Park. When it was a normal intersection I was never held up by traffic, so why they thought they needed traffic easing is beyond me.
Our roundabouts are filled with curbs and lanes, glad I am not driving plow trucks anymore, It would be a pain!
Cloverleafs were the traffic engineerâs answer to âwe have these new-fangled highways and donât know how to join themâ. The âcloverleaf mentalityâ is âletâs put streams of vehicles with wildly different speeds in direct conflict with one another and just hope everyone figures it out.â
Roundabouts are the answer to that mentality, only applied to surface street intersections.
Growing up as the son of a traffic engineer⊠those streams of vehicles, in theory are supposed to acclerate to highway speeds by the time they reach the highway. In theory. In practice that rarely happens which is why cloverleafs are essentailly obsolete.
Traffic circles are designed around the same principals and suffer the same pitfalls plus a few more. Like pedestrians.
The new diverging diamond interchange at Hawks Prarie over I-5 opened earlier this month, actually works well as long as youâre paying attention to the signs. Really weird to turn left directly off the ramp into traffic though.
MN did jughandles, no good pics but you basically pass a closed off intersection then make a u turn.
Cloverleafs would be fine if people would drive courteously and allow drivers onto or off the highway. Thatâll never happen. I was going to work early one morning and tried to pull off at a cloverleaf, the clown on the merge lane sped up and slowed down to prevent me from getting off in front of or behind him. While this was going on, another clown hit my rear end. I pulled off and so did the guy that hit me. He and his buddy got out (Clown car) and started an argument. Shortly after the argument started, the police showed up, and things calmed down quickly. After the even broke up, someone else walked up to me and gave me his card. He said he thought there was going to be a problem and pulled over to act as a witness if I needed one. He called 911 and summoned the police.
Well that stinks! Glad there wasnât any fists⊠or worse⊠flying.
I use to drive through one of the worse cloverleafs in the country every day (I-93 and I-95 (aka rt-128). Over 450,000 vehicles go through that cloverleaf every day.
This response basically works for anything in life:
â____ would be fine if people would use it as intendedâ
Love the DDI! Not only are they operationally more efficient â more green time for the through movements since you donât have to program green time for left turns â they are also safer, because youâve eliminated the turning movements across another stream of traffic (plus, people have to slow down and figure out what the heck is going on 
)
At least people are reasonable there most of the time. Iâve used that exit more than 2000 times since 1995, and people are mostly just interested in getting on or off without expressing their superiority.
It does have a lot of advantages, just getting used to it.
You say right turns were eliminated from the circle, but if Iâm reading it right there are arrows showing right to left traffic turning right before the circle and also in the circle. Am I missing something? By the way, in my city there are a growing number of traffic circles. If theyâre one lane only theyâre relatively easy to negotiate, but if you look at You Tube car crash videos youâll see all kinds of havoc at multi-lane traffic circles.
I wish people drove that way in the roundabouts here in New England. Itâs a free-for-all. Everyone thinks they have the right-of-way (even when they put up signs that say âYield to traffic in circleâ.)
When a motorist is approaching to immediately turn right they never enter the roundabout, they merely exit from the right lane through the cut-off and onto their exit with the right of way.
