Vehicles & Roads

Location: 
Six Mile Bridge – Port Mainline
Date of Incident / Close Call: 
2008-02-01
Company Name: 
Western Forest Products
Details of Incident / Close Call: 

While grading the mainline, the grader recently caught one end of the riser blocks, exposing a problem. The bridge is a common design (see drawing on next page) consisting of steel girders and a concrete deck with untreated timbers for the guard rails. The guard rail is attached to the concrete deck via a 10” x 10” block (connecting block) bolted to the outside edge of the deck.

A second 10” x 10” block (riser block) sits on top of the first, and the guard rail sits on top of and is attached to the riser block. Long blocks run from the top of the guard rail through the riser block and the connecting block.

The bridge was built in late 1996, and has been inspected every two years. It was due for another inspection. None of the pervious inspections had mentioned rot related problems in the timbers.

Visually, both blocks and the guard rails appeared sound. Further investigation after the grader caught the riser block proved otherwise. During the repairs to the bridge, all the connecting blocks, riser blocks and guard rails were replaced. In the process, rot was found around the bolt holes in all the blocks and rails. Inspections on two additional bridges has indicated the same problem.

Learnings and Suggestions: 

Timbers of all bridges over six years old should be bored to check for rot. If no rot is found, the bore holes should be filled with a waterproof epoxy caulking or similar product.

For more information on this submitted alert: 

Western Forest Products Inc., Queen Charlotte Forest Operation
Cory Delves or Debbi Thwaites
(250) 557-6810

File attachments
2008-02-01 Bridge Riser Blocks Exposed.pdf
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