The key benefit of the VSD, now being applied in Sydney, is its ability to use image-processing technology and extensive detection and known false alarm algorithms to alert the system operator to the presence of smoke in the shortest possible time - this is especially critical in a confined tunnel environment. Unlike traditional methods, by effectively detecting smoke at source, VSD does not rely on the proximity of smoke to the detector and is therefore unaffected by distance.

"We are extremely pleased - in conjunction with our Australian agent, Chubb Fire Safety - to be associated with such a prestigious project, which underlines the growing demand for VSD to be applied to minimise the risk that fire presents to road and rail tunnels" says Said Shaun Smith, regional manager for Australasia.

The system was commissioned with the full co-operation of the SHT control room staff and management and handed over in May 2006. Since that time thankfully the tunnel has been free from real time incidents. "We cannot afford to be complacent, the fatal fire within the Melbourne City Link Tunnel in March 2007 reminds us that we must remain vigilant at all times," says Bob Allen general manager Sydney harbour tunnel.