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The idea is to cut down on different phases where some trafficlights cycle through with medium sized crossroads as found in big cities.
Consider a crossing cycling through these phases on a crossing with direction a and b.
a being the north-south axis and b being the east-west axis. The roads
have 3 lanes, one straight, a left and a right turn
1.1 traffic from direction a can go straight and right. All traffic from direction b stops
1.1 traffic from direction a can go left. The cars turn left before cars coming from opposite directions. Traffic from direction b stops.
2.1 same as 1.1, but direction b moves, a stops
2.2 same as 1.2, but direction b moves, a stops
This is very rudimentary, it can go in more phases, or more or less lanes and/or direction combined (lane left can also choose to go straight), and traffic right might bypass traffic lights.
An improvement might be, that turns left are replaced with a loop 270° to the right after the crossing is passed.
The turns right begin before the lights and come in a buffer so they don't queue up traffic coming from the 90° direction.
It's vitally important that different crossing are synchronized with each other, so that drivers only have to wait for red lights when they make a turn left.
Synchronizing crossings is made a lot easier because only two phases have to be taken into account and the individual phases can last longer.
The construction costs also are decreased because no constructions as bridges or tunnels are needed.
Working on an in depth review of this system and making designs too
Turn off the lights and watch the carnage [lurch, Mar 20 2007]
A Jug Handle intersection in Cherry Hill NJ Area.
Click on the sattelite button to see what it looks like. [jhomrighaus, Mar 20 2007]
This one is just for U Turns!
[jhomrighaus, Mar 20 2007]
And Another for a T intersection.
[jhomrighaus, Mar 20 2007]
||I'm not sure but what it sounds like you are describing is politely known in NJ as a Jug Handle, Im not sure there is really anything new in your idea but If you dont live in an area with heavy traffic you would never have seen one. I will see if I can find an image.
||And you think that the people who always turn left on a roundabout are going to get it?
||It is called a "hook turn" and is to be found in wikipedia.
||I think he is describing a Michigan turn not the Jersey Jug handle.
The jug handle turn allows vehicles to turn left past the opposing que, the michigan turn does the opposite allows vehicles to turn left, (by u turn) before the que and requires much less Right of Way.
||Unless he's talking about split phaseing one direction and protective left turn phasing in the other direction.