A bridge bearing replacement changes how loads reach the substructure. While the original bearing is out, the load has to pass through a temporary arrangement. The closure plan needs to account for every transfer between those supports, including the point at which the new bearing takes load. A replacement bearing may be ready to install while the job is still weeks away from having a workable lifting sequence.
Survey the work area before committing to a sequence
Start with the bridge as it stands. Drawings identify the intended bearing positions and structural details, while inspection can reveal obstructions, repairs and dimensions that affect the space available. The team needs to establish how equipment reaches each support, where the old bearing can be withdrawn and whether there is room to place and inspect the replacement. Record what was measured and what remains an assumption for the designer to resolve.
On Brisbane’s Riverside Expressway, the project team reported limited space for jacks under the girders and difficult conditions for ground-supported temporary works. The case shows why access and support options belong in the first engineering review. Discovering a clash at the start of a closure can invalidate an otherwise workable sequence. Austroads Riverside Expressway case paper
Show what supports the bridge at every stage
An effective stage drawing answers a direct question. If work stops at this step, where is the load going? The answer may change during lifting, while the old bearing is free, during seating of the replacement and as temporary equipment is withdrawn. Show the intended reaction points and restraint arrangements for each stage. Make sure the designer can assess the supporting girder, headstock and any temporary elements together.
Queensland’s Transport and Main Roads maintenance note discusses allowing for jack placement, temporary support and future access in bridge design. The note describes a separate safety support for a jacking failure scenario. On an existing bridge, have the temporary works team confirm how the approved arrangement deals with a loss of support or an interrupted lift, and show where crews can safely leave the work if they cannot proceed. Queensland Transport and Main Roads, Technical Note 146
Make movement checks part of the closure plan
Movement can affect more than the bearing being replaced. In an Austroads paper on two Ipswich Motorway bridges, the authors describe controlling relative displacement and achieving the required final bearing level during a replacement using flat jacks. Their project is an example of designing the measurement and transfer sequence together. Equipment and acceptance criteria depend on the bridge and the approved method. Austroads Ipswich Motorway case paper
Before the closure, agree on the baseline readings, who takes them and who has authority to release each stage. Link each reading to a support location and a step in the approved sequence. Set aside time in the programme for a review if the movement, loads or seating condition depart from what the designer expects. A clear stop point gives the team a chance to check the cause while the approved support arrangement is still in place.
Separate bearing acceptance from reopening
The bearing record should let a reviewer trace the installed unit back to its location, approved details and inspection evidence. Useful records include the as-found condition, the installed bearing identification and orientation, surveyed levels where required, the load transfer readings and photographs of the final seat. Agree in advance which evidence the designer or asset owner needs before the temporary works can be removed.
Reopening also depends on what else the closure disturbed. Confirm that interfaces such as drainage, access and any traffic or rail protection arrangements have been handed back through the applicable process. In the maintenance record, capture what the team learnt about clearance and support access. That information can inform the next inspection and save the next replacement crew from repeating the same investigations.
A useful pre-closure review walks the people responsible for lifting, monitoring and reopening through the same stage drawing. If a step has an unclear load path, an unverified clearance or an unnamed person responsible for releasing it, resolve that gap while there is still time to change the plan.
Featured photograph. Hydraulic jack beneath a temporary bridge truss on North Carolina Highway 12 in 2011. The photograph illustrates bearing installation. Photo: NCDOTcommunications (CC BY 2.0).
