Parramatta River Pedestrian and Cyclist Bridge

Bonacci Infrastructure completed the design for the new Parramatta River Pedestrian and Cyclist Bridge which will cross the river at Alfred Street. As the head consultant, Bonacci Infrastructure was responsible for managing a team of architects, hydrologists, lighting engineers and various other disciplines in addition to delivering the structural and civil packages.

Two concept design solutions were presented to the City of Parramatta, including a cable stayed bridge and the arch bridge which was ultimately selected. The latter arrangement includes a steel arch which crosses the Parramatta River at an oblique angle with a single span of 85 metres. The bridge approach ramps and stairs are of reinforced concrete construction.

The diagonal arch, the first of its kind in Australia, created specific challenges with large out-of-plane forces and horizontal thrusts at the foundations. Pedestrian induced excitation and wind dynamics were also subject to close scrutiny.

Key challenges included designing for:

• Very low vertical and horizontal frequencies of the deck. The critical frequencies and accelerations were calculated and compared with the recommended comfort limits of European Norm 23984 for various classes of pedestrian loading;
• Tuned mass dampers to improve the bridge’s response to pedestrian induced loading;
• Significant out of plane forces on the arch due to the skew angle to the deck;
• Large vertical and horizontal forces acting on the arch foundation in conjunction with torsional moments; and
• Dynamic response under wind loading.