QUEENS AVENUE STEPS Parramatta, Sydney, Australia | 1996 - 1997
This commission resulted from a limited competition run by Parramatta Council’s foreshore development team, for the design of a set of public steps linking the residential area on the northern side of the Parramatta River with the new rivercat ferry wharf and CBD on the southern side.
The site is a steep embankment falling 11m from Queens Avenue to the banks of the river. Being a flood plain the site offered very poor foundation material, requiring deep bored pier footings.The site is also prone to flooding, with the 100 year flood level approximately half way up the embankment.
The design of the steps developed from a desire to reduce the number of footings to the absolute minimum, a central support and one at the top and bottom of the embankment. In order to span between these support points the steel steps have been trussed, with tubular chord members and the stringer acting as the web member.This long span arrangement also allows the maximum amount of unobstructed area beneath the steps to accommodate the large volume of water flowing during flooding.
The steps are prefabricated in 11 sections, which bolt together allowing individual components to be removed and replaced should they be damaged during flooding.To resist the large lateral forces imposed by flood waters the stringer is a composite box section made up of a 250mm steel universal beam fully welded to a 250 x 90mm steel channel.The channel carries the handrail and precast concrete treads, while the universal beam carries the truss chords.At each support point a steel ‘T’ beam transfers the load to the circular concrete pier footing.
At night the stair is lit by floodlights mounted on the underside of the landings allowing light to wash between the open treads, letting the steps themselves glow at night rather than flooding them with overhead area lighting.
Photographer: Ross Honeysett