Why are there different time cycles at ramp meters?
A 22: The red-green cycles will vary from ramp to ramp. The green light will typically be on for two to four seconds, and the red light may vary anywhere from two to thirty seconds depending upon traffic flow conditions. These timings will be set based on past traffic experience, but will be adjusted depending on current or future conditions. Because the ramp meters will be “traffic responsive”, the red-green cycles will be controlled by traffic at that moment. Radar detectors or sensors in the pavement indicate how heavy traffic volumes are on the freeways. Lighter volumes would send a signal to the ramp meter controller to “tell” the meter to speed up the red-green cycles to let more cars on the freeway. Similarly, if the signals detect heavier traffic on the freeways, the red-green cycles would be adjusted to space out merging traffic at a safer rate.
