Automatic ground marking method and apparatus

An automatic ground marking apparatus for marking ground, the apparatus comprising:

• a carriage responsive to carriage control signals for traversing the ground, the carriage comprising a controllable steering and drive system and a controllable marking system for marking a sign on the ground;
• a position determining system comprising a laser based electronic distance measuring device, the laser based electronic distance measuring device including a base station and a reflector, which system is arranged to determine the position of the carriage;
• and
• a processor responsive to the position determining system and generating the carriage control signals wherein the controllable steering and drive system respond to the carriage control signals to cause the carriage to traverse the ground wherein the controllable steering and drive system further comprises a plurality of independently controllable drive units, wherein each of the independently controllable drive units is coupled to a wheel of the carriage and mark out a desired sign on the ground.