Bridges

The Regency Road to Pym Street (R2P) project was a $354 million upgrade of a 1.8km section of Adelaideís North-South corridor. The project was delivered by the R2P Alliance consisting of the Department for Infrastructure and Transport (DIT), McConnell Dowell, Arup Mott MacDonald Joint Venture. The main structures on the R2P project were a three-span 134-metre long overpass, taking three lanes of motorway traffic in each direction over Regency Road, a 58-metre span pedestrian and cyclist overpass, 19 gantries and noise walls. This paper will focus on the challenges and lessons learnt from the design of the Regency Road overpass, which is a steel-concrete composite box girder. The general arrangement of the overpass is three continuous spans with four box girders. The central main span length is 60-metres over the intersection below. At the piers, the bearings were offset from the centre of the box, so as to minimise the overall span of the overpass by allowing for tighter turning circles in the intersection around narrower piers below.

To minimise work over the intersection, the main span of the overpass was constructed offline at the nearby Polonia Oval, including the composite deck. During a two-week intersection closure over the end of year holidays in 2020, the main span was moved into position in two halves using Self-Propelled Modular Transporters (SPMTs). The girders of the back spans were then erected using traditional crane lifts. This provided a balance between minimising disruption and keeping the SPMTs moves as simple as possible. Design challenges that were overcome as part of the R2P project included the application of the new AS5100.6 Fatigue code, additional Finite Element Modelling (FEM) modelling of box girders to capture effects that cannot be captured by a grillage model, and the provision of measurement criteria for the SPMTs overpass move, to ensure that the girders were not overstressed during the move. A simple yet innovative method of activating the pier hogging moments was also applied.