High-speed rail in Australia has been under investigation since the early 1980s. Every Federal Government since this time has investigated the feasibility of constructing high speed rail, but to date nothing has ever gone beyond the detailed planning stage. The most commonly suggested route is between Australia's two largest cities, Sydney and Melbourne, which is the world's second busiest air corridor. The Australian rail speed record of 210 km/h was set by Queensland Rail's Electric Tilt Train during a trial run in 1998. This speed is just above the internationally accepted definition of high-speed rail of 200 km/h (124 mph). The maximum test speed of 193 km/h set by NSW TrainLink's XPT is approximately that, and both the Transwa WDA/WDB/WDC class and XPT are capable of 200 km/h. However, these trains, as well as the V/line VLocity and Diesel Tilt Train, operate at a high of 160 km/h in passenger service.