1994 – Aug – Haley – Wollingford Lifting Bridge
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David Haley MIRSE Signals & Operational Systems Corporate Services Engineering Division Queensland Rail In Queensland, private railways operated for cane haulage by sugar mills are referred to as Tramways. The majority of these railways are 2' (610mm) gauge. Despite the gauge these are real railways with some mills operating long trains and hauling quite significant tonnages. The Pleystowe Mill operates trains up to 600m long and during the crushing season (June to December) hauls in excess of one million tonnes of cane from the cane fields to the mill. At present Queensland Rail has eighty five at-grade tramway crossings. Many of these crossings are at or near 90" and with seventy crossings on the North Coast Line (Brisbane - Cairns). The filler block diamonds used in 90" crossings have 50mm wide flange-ways through the heads of the running rails of both gauges. The filler blocks are provided to allow the wheels of QR trains to run on the flanges thus reducing the impact as the 2' gauge flange-way is crossed. The mechanical shock to the diamonds is considerable and is the main factor in their service life. To maximise the service life of the diamond, maximum train speeds of 40kph or lower are desirable. Queensland Rail presently operates trains up to 80kph over such diamonds, resulting in a maintenance penalty. In some cases diamonds are physically taken out of track outside the crushing season to extend their lives. For shallow angle crossings (e.g. 25O) it is possible to design diamonds which rely on wheel tread running only and produce much lower impact loadings. To date there has been little alternative to the 90" at-grade crossing. Grade separations involve significant earthworks and purchase of land to accommodate the cuttings or embankments. The gradient acceptable on the tramway is limited by the fact that the trains are operated with head end power only and brakes on the locomotive only. The land resumption is in general very expensive as both railways are in general running in prime cane land. Oblique angle crossings are more wasteful of land and due to the need to purchase land for the required deviations are not an attractive solution to upgrade existing 90" crossings.