Light Emitting Diode

From left to right the IC's are 7427, 7402, 7410

The company has three loading bays at the rear of the warehouse with limited space to manuever. When trucks arrive, the drivers can't see whether or not the loading bays are occupied. The warehouse manager wants a light system to alert drivers as to the availability of the loading bays, a red light indicating all bays are full, yellow indicating there is only one bay available and a driver should wait on the street if he sees another truck heading down the drive to the rear of the building, and a green light indicating two or more bays are empty.