Client: BMD Constructions
Asset Owner: Queensland Rail
Project Value: ≅$48 million
The Darling Downs and South West Queensland Regions produces around a third of Queensland’s agricultural products and cotton. The Queensland Government invested $48 million to upgrade the railway along the Toowoomba and Little Liverpool Ranges.
The upgrade project involved lowering the entire railway including the railway within eleven heritage listed rail tunnels constructed in the 1860’s. The objective was to create enough clearance for a 9’6” high cube freight shipping container to be transported by rail. By achieving this, it would decrease the quantity of heavy vehicles required to transport freight on the highway from South West Queensland to the Port of Brisbane. This reduces overall transport costs, maintenance on road infrastructure and traffic accident risk. This rail upgrade would in turn enhance agricultural growth in the region and boost commercial benefit to farmers.
In addition to each heritage listed tunnel, consideration has been given to the condition of structures, access roads, existing cut slopes, design life, construction methodology, proposed track possession regimes and safety during construction.
In order to lower four tunnels in one rail shutdown, BMD Constructions engaged Geoinventions to provide high level excavatability/rippability assessment of rock for Tunnel 3, Tunnel 4, Tunnel 5 and Victoria Tunnel. Geoinventions classified the rock material into a number of categories and rock consisted predominantly of either Sandstone or Tuff. Geoinventions produced a geological long section profile along each tunnel alignment indicating excavatability difficulty which could be adopted on-site by the contractor. Both the Point load index (Is50) and defect spacings of the rock were analysed so easy ripping or hard digging could be identified prior to the rail closure.
All rock lowering within these four tunnels were conducted successfully in one rail shift using a surface miner with zero impact on the heritage listed structures.