Jimmy Gully Pedestrian Bridge crosses Jimmy Gully along the Brisbane Valley Rail Trail (BVRT) near Harlin, Queensland. Jimmy Gully Bridge was a 6 span timber railway bridge that was decommissioned in the early 1990’s. Each span consisted of three girder lines with the two middle spans comprised of double stacked hardwood log girders. Each pile bent has three hardwood timber piles with the middle two bents consisting of five piles with the outer (batter) pile on each side providing lateral stability to the structure.
An extensive inspection of Jimmy Gully Bridge was completed by Wood Research and Development (WRD) technicians on 24 May 2016. The aim of the inspection was to complete the visual and EPHOD® (Electronic Pulse Highlight and Outline Diagnostic) compression wave technology analysis of the in-situ condition of the major structural elements of the bridge. The design of any restoration refurbishment, upgrade and repair strategies was then taken into account based on the inspection data collected.
WRD engineers determined that Jimmy Gully Bridge required a new superstructure and deck system along with several of the substructure elements requiring repair works. It was designed with a new pentachlorophenol-treated glulam girder and deck system with connecters that do not penetrate through the top surface which greatly increased the longevity of the structure as well as reduced maintenance costs. In addition to this Decaystop® (Borate Salt) rods were installed in the remaining hardwood elements in order to resist further deterioration of the timber caused by fungi growth.