LAS VEGAS - A viewer asks if freeway ramp meters function on a set schedule.
Typically, ramp meters operate weekdays between 6 a.m. and 9 a.m. and between 3 p.m. and 6 p.m. They may also be activated during periods of heavy traffic or special events, such as concerts. Drivers should follow instructions when the meters are running.
Ramp meters have built-in sensors to detect traffic flow. That technology follows what is called a "freeway responsive" mode of operation.
If freeway traffic is slow-moving, the meter will be on to prevent a flood of vehicles from entering the packed freeway. If freeway traffic is moving freely, the meter is off - allowing vehicles to access open lanes of I-15 or U.S. 95 without stopping.
In high-traffic corridors, traffic officials will sometimes turn off ramp meters to prevent vehicles from backing up on an on-ramp and spilling into surface streets. This is called "flushing out" the ramp.