The Regional Rail Link (RRL) is a 47.5 kilometre length of railway through the western suburbs of Melbourne, Victoria. The main aim of the project was to separate regional V/Line Ballarat, Bendigo and Geelong services from the electrified Melbourne suburban services, thereby increasing rail capacity and reliability.
The project involved widening a section of the existing rail corridor through the inner western suburbs of Melbourne together with new lines which provided a rail link to some of the newer suburbs in the western growth area.
The project was divided into a number of packages which were let to various design and construct consortia. Douglas Partners’ input began with site investigation drilling along the corridor and then providing tender design advice to consortia bidding for various construction packages. Douglas Partners was selected to undertake design work for many of the design packages. This included temporary retention design for the major rail underpass; review of the impacts of construction plant operating adjacent to existing bridge abutments and shaft support for service diversions, as well as numerous temporary batters and working platforms.
A range of ground conditions were encountered along the project corridor, ranging from soft silty clay (Coode Island Silt) to very high strength basalt rock. Other challenges arose from working in an existing rail corridor through an urban environment, sometimes with only a few metres clearance between the active rail line and the adjoining buildings.