Hera Engineering was engaged to undertake full pricing design of a proposed pedestrian crossing at the corner of West Coast Highway and Scarborough Beach Road, as part of the proposed tower at the Scarborough Markets site. Hera was engaged to undertake schematic design for the bridge and foundations, and worked closely with Multiplex to ensure that the challenging site restraints were satisfied.
The architectural intent and required clearances for the bridge were met by designing a pretensioned shell, which utilised the upstand walls as primary structural elements, achieving the absolute minimum structural depth possible and (just) allowing sufficient clearance to the underside of the bridge whilst maintaining the plaza level of the adjacent structure.
To achieve the minimal bridge depth without obstructing the footpath and meeting Main Roads requirements for clearances and visibility, both supporting foundations were cantilevered to cut down the bridge span. On one end the bridge was supported from a lift core with large outstand cantilever beams, on the other end it was supported from an architectural ‘V’ shaped column with upstand balustrade walls. This achieved an 29m clear span with only a 1.4m structural depth.
Hera also worked extensively with logistics and crane companies doing transport and lift studies to determine how we could get the bridge to site and lift it in place, with disruption to traffic occurring for one night only.
We were able to achieve this outcome by minimizing the weight of the bridge to the absolute structural minimum for lifting, to allow a two crane lift, and by considering all design cases from the offsite fabrication to the inplace case.
This bridge schematic design was approved by Main Roads as part of the DA approval for the development and was well below the project budget, which was an outstanding design outcome given the significant challenges for the project.