When used, they are usually repeated at regular distances to provide a continuous reminder of the lane status to drivers.
In the Australian state of Victoria, green and yellow are replaced by white, and there may be additional modes such as 'Centre lane turns only' at particular times of the day.
In Greece, they are frequently used in tunnels to indicate lane closures because of accidents or roadworks.
Many older toll plazas use conventional circular red and green indications to indicate the open and closed status of toll lanes; however, the use of circular red and green signals for this purpose is now non-compliant in the 2009 Manual on Uniform Traffic Control Devices, with lane control signals being the preferred indicator.
[2] The reason for discouraging the use of circular red and green signals for indicating the open and closed status of toll lanes is due to their use being contrary to their traditional definitions of stop and go.