They've tried flashing lights, neon signs, low-impact barriers, but sometimes nothing seem to keep oversize trucks from squeezing into tunnels. Officials in Australia have developed a novel warning system that stops trucks in their tracks without causing any damage -- a wall of water with a bright stop sign projected onto the water.
The system, called Softstop, was developed by Australia's Laservision and is deployed at the Sydney Harbor Tunnel in downtown Sydney, Australia.
Laservision is known for its work in attractions, special events and architectural lighting.
The system creates the illusion of a solid surface that instantly blocks both lanes of traffic. The Softstop Barrier System produces a pseudo holographic image that appears to float in mid air, commanding the attention of the motorist making the 'STOP' message impossible to miss.
The image of big stop sign is projected onto the water cascade after being triggered by height sensors located near the entrance to the tunnel. It's a last resort warning, but it has proven successful in stopping every truck that triggered it.
On the southbound lanes of the Sydney Harbor Tunnel, drivers will get three previous warnings before hitting the SoftStop device. If for some reason, drivers either ignore or fail to notice the earlier warnings, the SoftStop system really gets their attention.
"Unlike conventional warning lights, signals or signs that appear in the peripheral vision of drivers, the Softstop Barrier System is the only visual messaging system that appears in the direct view of drivers -- making it impossible to miss," says Laservision’s Director of Design, Simon McCartney.
It looks like a simple system, but according to Laservision's website, a lot of time and experimentation went into its development.
It has to deploy completely within three seconds, for example. Various projection technologies were tried during the development phase, and a suitable surface to display the projection had to be perfected.
The water curtain is a mix of water and air under pressure that is 'solid' enough to serve as an opaque backdrop for the projector, it has to be visible in daylight or dark, is has to remain intact despite wind and other conditions.
While the SoftStop appears to the driver to be a solid barrier, if necessary emergency vehicles can simply drive through it -- it's only water after all.
It's a really cool technology, and so far it's deployed only in Australia.
Check out the video from Sydney Australia's News10 to see how it works: