An animation of the Diverging Diamond. This helped me because I couldn't see the stoplights from the picture. I guess it's OK as long as there are signs. My main problem is with people trying to merge from ramps onto the main highway. Entering the highway from ramps has gotten to be a competitive sport here.
The main confusion with these (other than driving like the Brits for a brief period of time) is the same confusion that exists in most of the rural, non-cloverleaf interchanges: People are used to always taking a right-hand exit to get on to the interstate, regardless of which direction they want to go on it. As the video shows, if you want to go one direction on the interstate, you take a right-hand exit. To go the opposite direction, you take a left-hand exit. It's also confusing out here where I live because getting onto the interstate is a mixed bag of standard right-hand exits for both directions, or one right-hand exit for one direction and then a left-hand exit that crosses the oncoming lane of traffic...and they are not very well marked. You'll see the sign for I64 East, but it does not tell you which way you're gonna turn...it might be a right-lane exit, or you might be turning left. Many of these secondary roads go under the interstate, unlike that diamond interchange video. I wonder what solution they have for those.
I like roundabouts. Hitting Paris at rush-hour, and going around their second largest roundabout, in the vacinity of where the Bastille stood, I simply rolled down my passenger window, pointed to which street I needed to turn into, and drivers let me go there. Of course my four years of cab driving, in Chicago, gave me a skill set that most may lack, so I understand why many are intimidated by roundabouts. Austin is installing more roundabouts, these days. I know they provide for quicker passage through many major intersections. I'm all for them.
I, too, think roundabouts are a great solution. But roundabouts have the same limitation as all traffic intersection designs: the patience and competence of those who are using them. You know how some people are. They pull into traffic when (a) it's safe to do so, or (b) their internal timer has run down. And many people have limited capacity to remember the rules of the myriad scenarios. At first, 4 Way Stops were a reasonable alternative to traffic lights, but now people forget the rules of the more prevalent 2 Way Stops. So now we're at risk of the selfish drivers who take the right-of-way when they don't have it, and we're at risk of the hyper-polite drivers who inappropriately yield it when they do have it. I find the "you go ahead" crowd to be the most frustrating, because I want to be angry at them at for disrupting the flow, but they're just trying to be nice.
We got a few roundabouts here in the past years but going through one for the first time could be dangerous as hell. I went to the airport going through a new one for the first time and I naturally took my time since I was unfamiliar with it. Someone who apparently used it frequently came zooming by me as I nearly turned into him when I figured where I should go. To complicate matters, a second roundabout was just up ahead.
I've been through a few roundabouts in my time, but there was one in Maryland near a satellite office I was visiting, and it looked like it had 6 roads coming into it and cutting through it. It was a mess. The road I wanted went off to the left at about 10 o'clock, thought I could have gone on a road at 2 o'clock or one straight ahead.