BHP ME-TrackWeigh-2D In-motion Weighbridges
After reviewing its train weighbridge needs for the future, BHP chose in early 2015 to install new Meridian weighbridges at all of its load out sites. Some of these load out sites were concrete tunnels such as Yandi and Whaleback, others were bin load outs such as Eastern Ridge and Jimblebar.
The common feature for all loading stations was that BHP chose a ME-TrackWeigh-1D for the tare weighbridge and a ME-TrackWeigh-2D for the gross weighbridge. All weighbridges have bolt-on load cells. BHP has increased its focus on axle and bogie loads to maximise ore transported to port and at the same time to do it in a safe manner.
The 2D gross weighbridge has two weighing points and is more accurate that the 1D. It also has a greater level of redundancy as it is able to revert back to a highly respectable ME-Trackweigh-1D system should an incident occur that results in damage to a weighbridge bay.
New, 8.3m lengths of rail were supplied to Meridian by BHP. Each pair of rails had a specific hole schedule drilled in them, prior to delivery to Meridianís workshop. The rail-mounted equipment was then installed by Meridian.
Trackside junction boxes containing electronic equipment were largely the same at each site but each had unique mounting solutions. Controllers and software varied from site to site in order to match and interface with existing BHP systems. All electronic equipment was assembled and tested in Meridian’s workshop in Perth. All software was developed by Meridian.
In comparison, bin load out installations were much easier to implement than tunnel installations. At bin load outs, one has easy access to the track, one can work in daylight and the work is on normal rail track. In a tunnel, the environment is much more demanding. Both sites require track closures.
At all sites during the shutdown, 8.3m lengths of existing rail were removed; rail support spans were adjusted at the weighbridges; conduits were located in the ground or in the concrete slabs; new instrumented rail was installed; new junction boxes were mounted and cables were drawn and terminated.
In tunnels, BHP wanted the rail-mounted equipment to be protected from vehicle traffic. Robust cover plates were installed that would allow a 27.5 tonne suction truck to cross the weighbridge.
All projects were successfully completed in the shutdown period thanks to the efforts of the BHP rail crew and Austral Construction.