South East Queensland Timber Bridge Replacements
Contract Value: $9.3M
As part of the timber bridge replacement package for Queensland Rail, this project consisted of the demolition and replacement of the existing timber rail bridges at Rosewood, Kavanagh St, Gilfoyle’s Gully and Karrabin. These structures carry the up and down main for the Main Western Line. Project works consisted of construction of concrete sub structure, demolition of existing timber bridges, erection of new pre-stressed concrete decks, replacement of ballast and installation of track and over head line equipment (OHLE) to suit the new structures. Works also included reconstruction/ raising of all rail formation for the approaches at either end of each of the bridges.
All permanent substructure works were achieved while the track was live, to normal rail traffic without delay to services. The superstructure and earthworks was achieved over 3 no. schedules closures. 68 hours for Rosewood and Kavanagh St Bridges, and 44 hours for Gilfoyles Gully and Karrabin.
Time lapse footage of the construction of the superstructure of the Kavanagh St Bridge during the 68 hour SCAS closure can be viewed here.
Temporary works required shoring of the existing timber bridge to allow for excavation while not affecting rail traffic. Rock crane pads and piling pads to allow for safe working positions for the cranes to install the PSC Deck slabs and the piling rigs to install bored piles.
Due to the existing ground and flood levels at Rosewood Bridge, traditional bored piles were not an option and part of the contract was the design and construction of a micropile foundation system, which was completed by Keller Engineering.
Key features of this project include:
- Substructure Insitu Concrete: Kavanagh St and Gilfoyles Gully had 1200 dia bored piles approximately 3m off the edge of the live track. Kavanagh St, Rosewood and Gilfoyles Gully had headstocks and blade piers to be poured insitu under live rail traffic to within 50mm of the existing structures. Karrabin required the installation of 11no 2700 RCBC’s which was achieved with the use of trolley jacks as there was no room to crane the units into place.
- Precast Concrete: A precast area was set up at both Gilfoyles Gully and Kavanagh St sites, this allowed for the construction of the 3 no precast abutments which weighed in excess of 91t each. Each abutment required the match casting of 8no stress bar voids to allow connection to bored piles. All abutments were placed with no fitment issues. Precast relieving slabs were cast at the Walloon site compound.
- Earthworks: Rosewood Bridge site had a formation lift of 400mm in the centre of the job, which required additional raising of the formation over the length of 265m to a max width of 13m, this was achieved in 22 hours. The other sites also included earth works to the approaches.
- Superstructure Installation: Installation of 3 precast abutments, 288 bearing pads, 36 QR deck slabs, 24 precast transition slabs within the allotted times during each closure. This required multiple shifts with multiple large cranes (220t – 350t) both dual lifting and single lifting within tight confines with the additional hazards of Rail OHLE and Energex Power.
- Track Work: Removal and replacement of 883m of ballast, concrete sleepers and rail on both the down and up main, including guardrail for the full length of each bridge
- All works during each SCAS closure were completed within the allotted time frame with no delays to the rail network. Additionally, the project was completed within the contract time period.
- Fatigue and high pressure were concerns for such an immense amount of work to be completed in a short period of time. Extensive safety planning for each SCAS works meant completion of the 3 x SCAS with no medical treatment injuries of LTIs
- The project team works closely with QR communications team to keep the community informed. No complaints were reported during the project despite close proximity of residents to the site locations.