Way. Dupont Circle in D.C.
"NONCONFORMING" TRAFFIC CIRCLES
The early traffic circles often incorporated one or several problematic operational or design elements that would not be permitted in a modern roundabout. For example:
1. Entering traffic had right-of-way - At higher volumes this locks up the circle
2. Entries were regulated by stop signs or traffic lights - This reduces fluidity and capacity.
3. Entries were tangential to circle - This encourages high entering speeds and reduces the safety benefits.
4. Pedestrians crossed onto the central island - This is unsafe for pedestrians and disruptive for drivers.
5. The through road cut through the circle - Capacity, fluidity, and safety benefits are lost by the need to signalize the central intersection.
6. Circulating traffic was controlled by a traffic signal or stop sign - This decreases the fluidity of circulating traffic and can lock up the circle.
7. Parking was permitted in the circle - This reduces the capacity and safety of the circle by adding friction and conflicts.
Among the more notable nonconforming traffic circles are:
1. Dupont Circle in Washington, D.C. - where entries are regulated by a mixture of traffic lights, stop and yield signs, the circle includes a weaving section, and pedestrians walk onto the central island;
That doesn't cover half of the problem. There are about 3 lanes in the circle, but one is partially blocked by a concrete curb part of the way around. If you don't know exactly where you're going and when to exit, you'll not have any clue by the time you enter the circle. There are several traffic lights in the circle as well.
Driving in D.C. is a nightmare as it is (e.g. there are roads where it is illegal to turn left for about 10 miles, so if you make a wrong turn expect to be delayed at least 30 minutes trying to where you started), but trying to drive through Dupont Circle except at about 0530 on a Sunday morning is an excercise in futility.
It does have the advantage that Connecticut Avenue goes under the circle, so a lot of traffic can avoid it.
Cheers,
Scott.
