Cheticamp River Bridge Erection, Cheticamp, NS

 

The Cheticamp River replacement bridge is an 81.5m single span twin trapezoidal steel box girder bridge, that replaced an existing 4 span steel plate girder structure The new structure was erected using a complex phased construction method developed by HEC.

The new bridge horizontal alignment was offset from the existing bridge in order to allow the construction of the new bridge while leaving a portion (approximately 60\\% of the width of the cross section) of the existing bridge in place. The portion of the existing bridge remaining was used as a single lane alternating detour throughout construction. A temporary steel barrier was mounted to the edge of the existing deck to provide the required safety to bridge users and to separate the construction zone from the road.

The new vertical alignment was raised to allow for the greater structural depth of the new single span structure. The new structure was erected above the piers of the existing structure allowing the piers to be removed after the new bridge was in service.

Large timber lagging retaining walls were designed and implemented to retain the approaches to allow for partial demolition of the existing abutments and to facilitate the construction of the new abutments. 

The trapezoidal steel box girders were shipped in three pieces to site and then bolted together on one approach prior to transport across the existing structure and erection on the new abutments. Once the full length of each girder was assembled, it was placed on a specially designed truck and dolly system and driven across the remaining single lane of the existing bridge during one of the two allotted two hour full bridge closures. A full assessment and analysis of the existing structure was conducted to allow for the large loads associated with the passage of the girder on the truck. HEC developed minor, cost efficient upgrades of the existing structure to address potential overstresses associated with the erection method.

With the girder positioned to the immediate south of the new abutments, two cranes, one behind each of the new east and west abutments, were used to lift the girder off the truck and onto the new foundations. The erection was successfully completed from midnight until 2AM minimizing disruption to traffic

Once the full construction of the new structure was completed, traffic was diverted to it to allow the demolition of the remaining portion(s) of the existing bridge super-structure and sub-structures.

Client: Public Works and Government Services Canada

Value: $7.5 M

Year: 2010

Role: Preliminary and Detailed Bridge Designers