Sometimes I have to wait almost 1-½ minutes (but can seem like 5 minutes) to get a green on a side street or a left turn even when there seems to gaps in traffic. Why?
The coordination for the major streets is “time based”. What this means is that there is no constant video detection or a person watching traffic in a room controlling traffic. Basically, there are calculations made taking into account distance, speed and direction and then the controllers at each location turn the coordinated direction green in sequence as the platoon is supposed to arrive.

For time based systems there is a background cycle length of usually 120 seconds. During this 2 minute time frame every movement is assigned a specific amount of maximum time and the movements are served in a specific fixed order. So if you picture a clock with two minutes there is only one time in that 2 minute period where the controller will “look” at the side streets and left turns to see if there are any vehicles waiting. If so, then it will give them a green. If not, then it will give that extra green time to the coordinated movements and “look” at the next movement in the sequence. So if you are the first car at a side street or left turn and you happen to get there just after the controller “looks” to see if there was anyone there (and there wasn’t one second before you got there), then it will not look again for about 2 minutes. This can lead to the belief that the signal is not working properly.

Coordination is designed to move large groups of vehicles over long distances with minimal stops. This helps make up for the “extra” time you might have spent waiting on the side street and if you stay on that street for a reasonable amount of time, you will actually be ahead time-wise, gas-wise, frustration-wise and vehicle wear and tear-wise.

Show All Answers

1. What is Traffic Signal Coordination?
2. What is the best way/method for getting through the most signals without stopping?
3. Even if I drive at the speed limit I don’t seem to make it through all the lights. Why?
4. Which traffic signals are coordinated?
5. When are they coordinated?
6. Are signals coordinated in both directions?
7. Does coordination “break” at major intersections because the cross street volume is also very high?
8. Sometimes I have to wait almost 1-½ minutes (but can seem like 5 minutes) to get a green on a side street or a left turn even when there seems to gaps in traffic. Why?
9. Why don’t you coordinate all the time?
10. How do the signals operate when you don’t coordinate?