Bridges

Cover of Iron Cove Bridge Duplication
Iron Cove Bridge Duplication
  • Publication no: ABC-CAS006-11
  • Published: 31 October 2011

The $175 million Inner West Busway project was awarded to the Bridge to Bay Alliance in October 2007 and involved the implementation of a new city bound bus lane on the 3.5 km section of Victoria Road between Gladesville Bridge and the Crescent in Sydney’s Inner West. The project was delivered under an alliance model with the scope including environmental and planning approvals and communications in addition to the usual design and construction. The management of the planning approvals in parallel with the design was successfully achieved and saved considerable time for the project. The alliance comprised the client, The Roads and Traffic Authority of NSW, the contractor Baulderstone PL and consultants Hyder and Manidis Roberts. In addition to the challenging road works the centrepiece of the project is a 475.525m long, 16.845m wide bridge over iron cove complimenting the existing steel truss bridge. The new bridge curves gracefully adjacent to the existing bridge and incorporates two vehicle lanes, an a.m. peak dedicated bus lane and a shared cycle/pedestrian path. The bridge design consists of an 8 span, 3.3m deep single cell post tensioned reinforced concrete box girder with a typical span length of 53m to match the spans of the existing bridge. Due to clearance requirements beneath the bridge adjacent to the abutments and the presence of an optic fiber cable pit, a single 18m supertee span connects the abutment with the first span of the box girder at the Rozelle abutment. Similarly, two supertee spans of 25m and 27.5m connect the box girder to the Drummoyne abutment, in order to provide sufficient clearance underneath the soffit. Despite initial concerns about the viability of the method due to site constraints, incremental launching was finally selected as the construction method for the box girder. Although significant additional temporary works were required as part of the ILM scheme due to the site geometry, the ILM solution provided the least impact upon the many stakeholders and was considered to have the least safety and environmental risks compared with other solutions.