There *is* an intersection there, they form part of the intersection with the interstate.
That is a rather odd junction design though - more common would be a large elevated gyratory linking the two slip roads across together...

The predominant traffic flows are little affected by these small roundabouts - the tapered entrances/exits permit the more normal looking manoeuvres to just flow as normal, but the roundabout permits continual flow, even where the manoeuvres differ from the common directions.

(For a more 'normal' version of that junction - imagine a single oval or round circulation with two bridges over the highway and with the slip roads feeding into the sides of the circulatory... as an 'after thought' conversion that seems to work well enough though).

We see those types of roundabouts a lot coming off the motorways in the UK, they are quite common in Holland too.

They look like they simpl provide access between S Racine and I43. How was access handled before? By turning lanes on S Racine? Or was it right turn only when you got to S Racine? I guess I could see how traffic piling up to make left turns onto or off the ramps could cause serious congestion, but in a situation like that it seems making traffic flow more efficiently simply causes more traffic than the system was designed to handle to travel that way. Plus, eventually you ARE going to hit a traffic light and that'll cancel out any increased efficiency the roundabouts provided. It'll probably make it worse, since the more freely-flowing traffic through the roundabouts means there'll be that much more stacked up at the light. You can't just stick a roundabout somewhere and say "voil�!" - the road system has to be addressed as a whole.

That sort of layout is very common in the UK, typically at junctions with a lower volume of traffic. The alternative is one big roundabout such as this which obviously requires two bridges rather than one.

They're good at places people regularly go so they can get used to them.
We've got one at the airport and it was horrible having to drive through there on the way to work. Regulars were fine after a while, but being the airport, you had a constant influx of people that had never seen it before and COULDN'T READ THE FRIGGIN SIGNS to know what to do. This was a single lane one too! LOL
Many times I saw someone stop at each road on the way around. Or someone thinking they're being neighborly waving someone on when that person was to their right. JUST DRIVE!

Well it's not really an intersection. And if you look at the bottom 1/4 of the upper roundabout and the upper 1/4 of the lower you will see there is no reason to ever drive through there. The pavement is still brand new for that part of the circle and the plows don't even bother plowing it. The only time ANYONE would go through there would be to turn completely around, which by chance was much easier to do before the dual roundabouts were installed. They are really just gigantic round off-ramps.

I forgot to mention that there have been at least 2 fatal motorcycle fatalities on the northern loop as well.

What I should do is post a series of pictures with all of the signage required for this abomination. There are at least 40 signs for these 2 roundabouts beginning with "warning roundabout ahead" 1/4 mile up the street both ways, dozens of yield signs, and arrows to keep the sheep grazing the correct direction.

Easily done with google street view, you even get high res street views in your roundabouts. Drag the little
man off the upper right and plave him where you want to start.

http://goo.gl/maps/jf3LG

LOL I hadn't thought of that. Just popping down to street level and doing a 360 spin without moving you can see the forest of signage, arrows, red flags, and "warning: SIGN AHEAD" signs.

Oh, no - on military bases everyone typically drives like an old lady, studiously following all the traffic laws. Getting a ticket means either: A) "Reply by Endorsement" hell on earth though the chain of command with the extra threat of the damned canned defensive driving course, or B) paying a fine through the FEDERAL Magistrate, depending on who pulled one over and wrote it up.

At Fort Lewis one of my guys got popped by one of the Feds (not the MP's) for doing 35 MPH in a 20, and forgot to mail in the fine. So we had to go down to the Federal Court to settle it. So here's the docket for the day: Kidnapping, Drug Trafficking, 15 miles over the limit speeding ticket, Child Porn Ring, Ivory Smuggling.... The judge thought it was hilarious - everything else was serious federal felony indictments, and here stuck in the middle is a friggin' traffic violation that if had happened anyplace else but a military base would be dealt with by the most junior judge on the bench.

"Hadn't done one of these for thirty years," he started, then looked at me, "you his lawyer, Sergeant?"
"No sir," I replied, "I'm his section chief."
"That's one way to make sure he gets here. What say you, Private," he asked my poor guy, who looked about twelve years old out of fear.
"I'll pay closer attention to the speed limit through there, sir," and, after realizing the room went silent from an open admission of guilt, "no excuse, sir."
Somebody behind us snorted a laugh.
"Forty five dollar fine suspended," he judged with a smile, then turned serious, adding "slow it down, son, we need you in one piece."

So we hang around to get something saying it was taken care of for the Battery Commander and then go back to the unit, where I learn I still had to do the Reply By Endorsement nutroll and show that I had included driver safety into my section's training plan. At least I could do the training rather than force anyone to endure the all day Saturday class given by an over-zealous instructor.

[edit]

We later learned that there is actually a federal magistrate on post, but for some reason their office was closed at the time, so we had to go to the "regular" federal courthouse. To this day I think some clerk there put us in the criminal court as a joke on the judge.

This was well over 20 years ago; I don't think they have civilian cops on post anymore beyond a few security guards at the gates; they weren't federal marshals but had arrest powers. He said it wasn't the MP's that wrote him the ticket, but he was a knucklehead and would be confused by a civilian cruiser and a guy in anything but BDU's, especially if they were older than 25. I dunno - I was always able to talk my way out of a ticket with an MP.

LOL Dart, that sounds like when I was inprocessing at Fort Bragg. Some old retired CSM essentially told us we were in for the same sort of rigamarole if we even barely went over the speed limit. As a result I always, always, always made sure I knew what the posted speed was when I was driving.

There are the entrance and exit lanes for the interstate , no ? maybe they were bored to fill the cemetary nearby.

Definitely agree with the on-base driving bit. I make sure I'm doing 5 miles less than the speed limit due to the consequences involved and the sheer number of police traps employed... Unless of course the speed limit IS 5 MPH, at which point I just walk...

Back to the roundabouts though: Love them when there isn't much traffic involved. The problem lies in the fact that with heavy traffic (as in traffic is backed up) you are pretty much guaranteed to get screwed over for hours if you have to cede the right of way to the main artery entrance. You Brit guys seem to lose the ability to follow the rules of the road when traffic gets backed up, and God help you if you're hoping that most folks will politely wave you in front of them...

At least traffic lights will allow you to move every once in awhile if you aren't on the main thoroughfare.

I get it you never drove a car in Italy...
Senior citizen and Italian women

On some large circulatories there are traffic lights near the entrances to the roundabout, or alternatively on segments of the circulatory road itself.

This is an example of the latter, fairly nearby, you can use streetview to look at the road layout. Predominant flows are North-South through the underpass, with City traffic heading to/from the West, and local traffic to the village to the East (this bypasses the narrow village highstreet of Batheaston - and links (via the A46) the Motorway to the North (M6) with the A4 road between Bath and London).

https://maps.google.com/?ll=51.398603,-2.336794&spn=0.00583,0.009645&t=m&z=17

It used to be Racine Ave straight through over the bridge- no stop lights or signs, with open on-ramps, and the off-ramps had stop signs. Now it's the same thing but 4 times as big, 10 times as many signs, and 20 times as expensive. And we've got 2 roundabouts that only need to be 75% round.


Here's another one they put in about 20 minutes east of me where there is no real intersection, just a road through E-W and a turn off for industrial park.


Map View

You're right the circles could be replaced with teardrop shapes,
I wonder what they were thinking - that someone might want to
just go round a few times while they figured out which way they
wanted to go? Looks like the intent there was to save the cost
of a cloverleaf while avoiding stop lights/signs, but considering
the "slow to 15mph" signs, that wouldn't seem to have made for
much traffic flow improvement.

...I have had a few interesting encounters with roundabouts.
I mentioned a while back in another thread about my experience
landing in Britain for the first time, about 20 years ago, at
Heathrow, at 8pm one evening, picking up my rental car, and
driving it off the lot to immediately deal with meeting my first
ever roundabout about two minutes after starting to cope with
my first experience with driving on the wrong side of the road.
That was ...interesting. It was amazing I was able to fend as
well as I did.

The next memorable event was later in the same trip, when I had in
mind to do a bit of sightseeing, in Bournemouth. I entered the city,
and found that I couldn't locate an available parking space, and
there didn't seem to be any stop lights on the major roads, so I
didn't have any time to stop, look around, check my map, and choose
which way to go. It was just one roundabout after another with
no stopping anywhere. I felt like a pinball. I was rapidly utterly lost.
I ended up leaving the city about eight minutes later, having never so
much as slowed down, and finally found a place to pull off and try to
figure out what highway I'd been dumped out onto, and how.

Since then, roundabouts have begun showing up on this part of the world,
fairly sparsely at first, but lately they've been springing up more
often. On a wander up the Fraser Valley this summer I encountered
one out in the countryside, two moderately major two lane country
roads crossing at a single lane roundabout of fairly small diameter.
It seemed perfectly adequate for the purpose until we saw as we
approached there was a full size logging truck coming the other way,
and it became immediately apparent he was much too large to follow
the loop. Sure enough, as we were going round in one direction, he
just drove straight over the middle of the ring in the other direction.
Fortunately there was no other traffic from the cross road. I could
see that might have been a bit distressing for them...

Another wreck on my roundabout today. This time the southern one, looks like a Toyota Paseo cut the circle and blew up front suspension/ front left lower ball joint. Car sideways across the circle with a crack in the windshield where the driver's head hit and the front end of the car dragging on the ground. He was still waiting for the tow truck when I went through, also new berlin squad car there blocking traffic.

There are no roundabouts around here. When I visit the UK they are everywhere and lots are multi lane. I went to visit my cosuing in Ohio last month and encountered a roundabout......it was very weird. I had never gone round in that direction

I do agree that they work MUCH better than regular intersections , especially if there are many roads and many lanes