Method of generating bidirectional green waves of traffic by alternating lights in zones
A method of managing traffic lights that generates waves of unimpeded traffic in both directions of a roadway. The roadway is divided into an even number of zones of equal length, which are divided into two groups of alternating zones. A traffic speed and a traffic light duration are selected so that the zone length equals the traffic speed times the light duration. Initially all lights in all zones of one group are set to green, and all lights in all zones of the other group are set to red; then lights are switched in the next cycle to red for the first group and green for the other group. This pattern repeats. The arrangement of alternating zones and the relationship between zone length, speed, and light duration allows vehicles moving in either direction at the specified speed to encounter only green lights, enabling dramatic reductions in travel time.
1. A method of generating bidirectional green waves of traffic by alternating lights in zones, comprising:
dividing a roadway comprising traffic in two directions into an even number of zones, wherein each zone of said even number of zones has a same length;
partitioning said even number of zones into two groups, each group of said two groups comprising half of the even number of zones, wherein zones in a first group of said two groups alternate with zones of a second group of said two groups along said roadway;
selecting a speed limit for said traffic in said two directions of said roadway;
selecting a traffic light duration equal to a length of said each zone divided by said speed limit;
controlling traffic lights in said roadway by repeatedly
setting all traffic lights within said zones in said first group to allow said traffic to proceed in both directions of said roadway, and setting all traffic lights within zones in said second group to stop said traffic in said both directions of said roadway, for a period of time equal to said traffic light duration; and,
after said period of time equal to said traffic light duration,
setting said all traffic lights within said zones in said first group to stop said traffic in said both directions of said roadway, and setting said all traffic lights within said zones in said second group to allow said traffic to proceed in said both directions of said roadway, for said period of time equal to said traffic light duration.
2. The method of generating bidirectional green waves of traffic by alternating lights in zones of claim 1 , wherein said roadway comprises all or a contiguous portion of a street in a city.
3. The method of generating bidirectional green waves of traffic by alternating lights in zones of claim 1 , further comprising controlling traffic lights in cross streets of said roadway to allow cross traffic to proceed within said zones of a group of said two groups when said all traffic lights within said zones of said group are set to stop said traffic in said both directions of said roadway.
4. The method of generating bidirectional green waves of traffic by alternating lights in zones of claim 1 , wherein at least one zone of said even number of zones contains two or more traffic lights.
5. The method of generating bidirectional green waves of traffic by alternating lights in zones of claim 1 , wherein
said speed limit is greater than or equal to 30 mph and less than or equal to 60 mph;
said traffic light duration is greater than or equal to 30 seconds and less than or equal to 120 seconds; and,
said length of said each zone is greater than or equal to 0.25 miles and less than or equal to 2.0 miles.
6. The method of generating bidirectional green waves of traffic by alternating lights in zones of claim 1 , wherein said zones in said first group alternate with said zones of said second group along said roadway such that said each zone of said first group is adjacent to a zone of said second group.