One Way Flow Plates | Surface mounted or Cast InOne Way Flow Plates Surface mounted or Cast In Our One Way Flow Plate controls Traffic Flow to one direction only and is designed to work in groups to provide full road width coverage. As a vehicle passes over the plate, the ap is pushed down, allowing the vehicle to pass, the rubber buer on the reverse of the ap ensures noise is kept to a minimum. Once the vehicle has passed the ap returns to its upright position. Manufactured from heavy duty steel