Bridges

Roads and Maritime Services New South Wales (NSW) is currently undertaking an $84 million project to upgrade the Pacific Highway and Wyong Road Intersection at Tuggerah on the NSW Central Coast. The project involves conversion of an existing roundabout to a signalised intersection and duplication of an existing bridge over the Main Northern rail line connecting Sydney and Newcastle. The project also includes approximately 1km of retaining structures (up to 11m high), modifications to the existing rail overbridge, extension of an existing pedestrian underpass and relocation of above and underground utilities. The project will improve safety, ease congestion and improve travel times for approximately 55,000 vehicles which currently use the intersection daily.

A key challenge for the project was designing the 45 degree skew, four span Super-T bridge and substructure to be installed adjacent to rail within a designated number of track possessions. The bridge design was driven by a number of constraints, the foremost being the proximity of the central pier to existing rail, direct current overhead wiring (OHW) and high voltage (HV) rail aerial feeder lines. The clear distance between the central pier and centreline of the nearest track is 3485mm.

The project team worked with various stakeholders to develop a hybrid cast in-situ / precast concrete central pier to expedite construction and to reduce safety risks associated with working in such close proximity to rail. An animation of the anticipated bridge construction was developed to communicate the proposed design and associated construction sequence to all stakeholders. The project is currently under construction with works on the new bridge nearing completion.

This paper focuses on how the risks associated with bridge construction adjacent to rail were addressed during the design.