Cheticamp River Bridge Timber Lagging Wall, Cheticamp, NS

 

The Cheticamp River Bridge Replacement project involved replacement of the existing four span structure with a new single span 81.5 m twin steel box girder bridge structure.  Due to site constraints and to minimize impacts on the environment and surrounding private properties, the south half of the new bridge had to be constructed in the same location as the north half of the existing bridge while maintaining one lane of the existing bridge open to traffic at all times. Harbourside Engineering Consultants designed an innovative 5.2 m high timber lagging wall that supported the highway immediately behind the wall and could be constructed while the bridge was open to traffic.  The wall system included cast-in-place concrete deadmen, tie rods drilled horizontally through existing roadway fills, steel H-piles, walers and timber lagging.  HEC also designed anchorages to the existing abutment to permit construction of the wall given the existing skew angle.  The timber lagging wall was chosen over an SSP wall mainly due to the presence of cobbles in the soil stratum that would have made continuous driving of the SSP sheets expensive and time consuming. Without this timber lagging wall a closure of a portion of the Cabot Trail Highway would have been required.

Client: Public Works and Government Services Canada

Value: $500,000 (Approximate, timber lagging wall structure only)

Year: 2009

Role: Structural Design Engineers