Edmonton, Alberta · Steel through-arch bridge · 2013–2017
The fabricator and the design team were not working from the same model.
What happened
The Walterdale Bridge replacement was budgeted at approximately $132 million. The final cost reached approximately $155 million plus related works — an overrun of roughly $23 million. The bridge opened roughly two years late.
Fabrication of the steel arch was carried out overseas and the components were shipped to Edmonton for assembly. Tolerance reconciliation between the design and the fabricated steel was produced after fabrication had already begun.
The information failure
Technology and Process. A transcontinental fabrication chain was run without a shared information environment — no single place where the design model, the fabrication model and the tolerance record were the same record.
When reconciliation is produced after fabrication starts, it is no longer a check. It is a discovery, and by then the cost of acting on it has already been committed.
What would have been different
A common data environment specified in the contract, with the fabricator inside it and model exchange gated at defined points, is the standard control for this class of project under ISO 19650. It does not remove fabrication risk. It moves the discovery of a mismatch to before the steel is cut rather than after.
Sources
City of Edmonton project briefings and Council reports. Design competition and contract documents. Edmonton Journal. Daily Commercial News / ReNew Canada.