REGISTER

AL Neal MIE (Aust) MIRSE

Chief Project Engineer, MNM

The advantages of coded track circuits, compared with ordinary D.C. type track cricuits are well known; the lower power consumption, longer practical lengths, and the elimination of vital lineside wires, either cable or pole line.  On the Mt. Newman Railroad the long lengths and information transmission abilities are exploited to the full.  Indeed we operate some of the longest track circuits in the world, up to 14km without any repeating cut sections.  There are no vital lineside cables along the railroad, all vital information is transmitted through the coded track circuits. Cabling is limited to a power cable, telemetry cable and a non-vital telephone cable (used for hot-box and dragging equipment detector equiment).

The high cost of maintenance of the existing coded track equipment, the future expected major maintenance required led to investigations of alternative systems to the present G.R.S. "Trakode"system of track circuits. These investigations began in earnest about two and a half years ago. Following these investigations two types of fully solid state equipment have been put into service, two track circuits of G.R.S. "Trakode II", covering 11 km of the single track main line, and eight track circuits of "Electrocode", manufactured by the Electropneumatic Corporation in U.S.A., covering a total of 42 km, all but 3 km being on the single track main line, (the remaining 3 km is installed on a passing track).

Experience in operating the systems has clearly shown that there are significant cost savings, enough to justify the conversion of all the existing relay coded tracks.  Experience has also shown that even in the very harsh climate, and in an area subject to regular and intense sumner lightning storms, the equipnent performs more reliably than the present relay based system. There have been some problems, and these will be discussed a little later.