Changed traffic conditions - (up)
Ramp meters, or ramp signals, are quick change traffic lights on motorway entry ramps to manage the flow of vehicles entering the motorway.
When the red lights appear, drivers stop and wait for the green signal. When lights turn green, one vehicle per lane will be able to drive along the ramp and merge onto the motorway.
On average, more traffic incidents occur in New South Wales on a Friday (89.53) than any other day of the week!