Bridges

The Ashton Avenue Bridge is a replacement of the original three-span timber bridge over the Perth-Fremantle Rail line in Claremont, Western Australia. The replacement bridge comprises a single span of 19.1 m with a trafficable width of 11 m between kerbs and a 3.5 m shared path on each side of the bridge. Several constraints drove the design development. The first key constraint was that due to the road vertical alignment and required rail clearances, the span to the depth of the bridge was limited to a minimum of 37 at mid-span. The second key constraint was that, due to the bridge spanning operating rail, construction was restricted to a one-weekend shutdown for installation of the deck planks, while the rest of the construction activities were to be completed during regular rail operation.

An innovative solution was developed to accommodate the above constraints; this comprised a combination of a superstructure consisting of 20 No precast battledeck planks with a cast in-situ reinforced concrete deck slab and integral abutments supported on piled foundations. The integral abutments allowed the battledeck planks to act compositely in both sagging and hogging, which reduced the maximum sag moment considerably. Using the combination of batteledeck plank and integral abutments made it possible to use a superstructure with a depth of 515 mm for 19m bridge span. This paper will outline the constraints and the design requirements that characterised the design of the battledeck planks and the integral abutments and then will discuss the key features in the design and construction of the Ashton Avenue Bridge.