Riverside County and some cities in the US state of California have installed radar speed feedback signs in a bid to alert drivers about their speed.

The feedback signs display the motorist’s speed and flash a message to alert the drivers if they exceed speed limits.

The device can also be set to flash at a particular speed above the limit.

Riverside County has also received encroachment permits from Caltrans to install the devices on some highways across the state, according to pe.com.

The digital signs have already been used in urban areas and Riverside has so far installed 40 of the signs.