Track
The O-Bahn track is made of concrete; it is elevated above ground because of the poor quality of alluvial soils along the River Torrens, which frequently move due to seismic shifts due to their high level of plasticity. Large concrete pylons were cast into the ground to ensure stability, to a depth of up to four metres. On top of the pylons are concrete sleepers on which the track runs. 5,600 pylons were drilled in place to support 5,600 sleepers and 4,200 prefabricated L-shaped track pieces, sited at 12-metre (40-ft) intervals. The width of both tracks, sitting on the sleepers, is 6.2 metres (20 ft). The O-Bahn's concrete tracks were narrower and lighter than those of the initially proposed light rail development, and put less stress on the land. The concrete components were precast and then laid onto piers.
At the city end, the O-Bahn begins at Hackney Road, opposite the East Parklands, where it enters a 60-metre (200-ft) tunnel at a speed limited to 40 km/h (25 mph), due to the tight initial corner, ensuring that the rear tyres (especially trailer tyres of articulated buses) do not 'scrub' against the track. Speed is gradually increased to 80 km/h (50 mph) for most of the trip to Klemzig Station. Once en route to Paradise Interchange, the speed limit is 100 km/h (62 mph), with 90 km/h (56 mph) on tighter corners. The limit on the remaining section to Tea Tree Plaza Interchange varies between 100 km/h (62 mph), 90 km/h (56 mph) and 80 km/h (50 mph). The average speed including stops is about 60 km/h (37 mph). On some sections 115 km/h (71 mph) has been easily achieved in tests. On entering interchanges the O-Bahn ends and the speed limit is 40 km/h (25 mph). In the interchange area, the speed limit is 20 km/h (12 mph). The O-Bahn is officially considered a road, due to a court ruling in the early years of the system's operation. This ruling permits the South Australia Police to install speed cameras and fine speeding drivers.
Cars entering the O-Bahn are deterred by a large number of signs at entrance points and a "sump buster" device that rips out a car's sump (oil pan) if it gets onto the track. An average of four cars per year enter the O-Bahn and must be removed by crane.
Read more about this topic: Adelaide O-Bahn
Famous quotes containing the word track:
“Our achievements speak for themselves. What we have to keep track of are our failures, discouragements, and doubts. We tend to forget the past difficulties, the many false starts, and the painful groping. We see our past achievements as the end result of a clean forward thrust, and our present difficulties as signs of decline and decay.”
—Eric Hoffer (1902–1983)
“Commit a crime and the world is made of glass. Commit a crime, and it seems as if a coat of snow fell on the ground, such as reveals in the woods the track of every partridge and fox and squirrel and mole.”
—Ralph Waldo Emerson (1803–1882)
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—Harry Fink, U.S. screenwriter, Rita Fink, U.S. screenwriter, Dean Riesner, U.S. screenwriter, and Don Siegel. Harry Callahan (Clint Eastwood)