safest in Australia. A speed limit of 80 km/h along the main tunnel motorway and 60 km/h on exit and entry ramps has been set. Variable message signs 120 metres apart within the tunnel are used to convey important information. Six fixed speed cameras in 10 possible locations are in operation. There are 500 CCTV cameras, which can be viewed on 46 individually controlled monitors in the control room. An underground loudspeaker system is available if needed. Micro-heat detectors are able to measure temperature every six minutes and fire sprinklers that can deliver 600 millimetres an hour of water, are claimed to be able to put out a major fire in minutes. There is a 24-hour control room at Kedron with two operators and a supervisor. See also Airport Link, Sydney Road transport in Brisbane South East Queensland Infrastructure Plan and Program TransApex Notes External links Official site BCC project site TransLink project site for Northern Busway Forum - AirportLink Forum Buildings and structures in Brisbane Toll roads in Australia Toll tunnels in Australia Tunnels in Queensland Roads in Brisbane Tunnels completed in 2012 Transport infrastructure completed in 2012 Road tunnels in Australia