The Australian authorities have come up with an innovative way to prevent tractor drivers from crashing their oversized vehicles into the Sydney Harbour Tunnel, which could result in fatalities and costly repairs.

The Softstop system, developed by a company called Laservision back in 2011, projects an image of a bright red stop sign onto a water screen at the entrance of the tunnel. This gives an impression of driving right into a stop sign. The system only activates if the driver ignores the flashing warning signs as he approaches the tunnel.

Projection of images onto a water screen is often used in the entertainment industry. A good example is the water laser show at the Marina Bay Sands Atrium (By the way, the show is free).

The system could also be activated for other reasons, such as warning the drivers to stay away from the tunnel in the event of a fire or a severe accident.