New Athabasca River Bridge
This $70M project involves constructing a new bridge across the Athabasca River on Highway 813 in Alberta. Alberco Construction Ltd. serves as the general contractor, replacing a 72-year-old bridge. The replacement bridge, 259m in total length, accommodates two lanes and a sidewalk. COWI is the designer of this bridge with a span arrangement of 80m - 99m - 80m including two river piers. The superstructure comprises four lines of 3.4m deep plate girders.
Total Steel Erected: Approximately 1600 tonnes across four girder lines.
Erection Methodology: The project utilizes both single and tandem crane operations, employing 400T crawler LR1400 and a 500T mobile crane LTM 1500 models.
Erection Sequence: The initial erection stage involved installing 21.5m long, 52-tonne pier girder segments by the crawler positioned adjacent to the pier. Segments 1 and 2 were spliced behind the west abutment in a staging area, forming a 71m girder segment. This was followed by the assembly of two girder pairs, each weighing approximately 200 tonnes.
The south pair was first erected, with the west end supported on a trailer and maneuvered backward by the truck as the east end was lifted by the LTM 1500. The mobile crane was located behind the abutment and in a trench to allow the pair to be launched overhead above it. The pair was launched until it reached the mobile crane's maximum radius limit. Then, the crawler began to support the east end using a load transfer triangle. The pair continued to be launched further. Eventually, the mobile crane lifted the west end, while the crawler lifted the east end. Together they performed a tandem lift to position the girder pair as intended.
The final stage on the west side involved erecting the 17m long, 23-tonne cantilever segments connected to the cantilever of the pier segments (Segment 4) resulting in a cantilever length of approximately 30m. The Eastside mirrors this process, with the last stage involving the center drop in a piece of 39m with 70-tonne single girder segments erected using an LR1400 crawler or equivalent positioned on the east berm.
Stability Measures: Stability for the first girder segment erected at the pier was achieved through chain lashings at the Pier and the temporary tower. To guard against potential wind loads from a 1 in 10-year event, transverse and longitudinal restraints were implemented at abutments and pier, ensuring the structure's restraint during erection.
Challenges Addressed: Due to limited space on the available berm, Segments 1+2 were erected in a unique way that required a crane-assisted launch, handover from one crane to another, followed by a tandem lift. This complex set of maneuvers required careful planning, coordination among various parties, and meticulous engineering to ensure there were no interferences between the various pieces of equipment used.
Location
Town of Athabasca, AB
Duration
2023-24
Capital Cost
CAD $70M
Client
N-Force Crane & Equipment
Services
Construction Engineering