MELConnx requested D&A to conduct an alternative design to that proposed by their current design partners. In response, our team developed a bespoke structural design arrangement for an 850m long rail viaduct constructed east of Bayswater Station and following west to seamlessly meet with the cut-and-cover tunnel constructed under the Tonkin highway. D&A’s innovative design provided a unique solution to address site constraints created by the need for large bridge spans to accommodate the existing Midland line and acute angled road crossings. By rotating the headstocks longitudinally and creating an integral connection between the superstructure and substructure, this innovative design optimised the use of the maximum beam length currently achievable by the precast yards in Perth.
In addition, to eliminate large excavations near the existing rail, D&A developed a monopile solution whereby each column was supported by a single large diameter pile, thus eliminating all pile caps on the project. Our team
spearheaded the integration of Geotechnical and Structural engineering to optimise the response between the piles and the integral bridge structure. The superstructure design further incorporated a bespoke designed prestressed box beam with precast transverse slabs forming a through type deck arrangement. This allowed the beams to act as secondary containment for the rail, thereby enhancing safety, whilst minimising structural depth.