Bonnie Road Bridge Emergency Collision Repairs
Location: Meteghan, Nova Scotia
Client: NS Department of Transportation and Infrastructure Renewal
Duration: 2015
Key Staff: Robbie Fraser, P.Eng, Wade Pottie, P.Eng.,
Project Description
The Bonnie Road Underpass is a three-span continuous six (6) steel plate girder bridge with a composite concrete deck measuring 42.07m (12.78m-18.5m-10.78m) in length that spans over Highway 101 in Meteghan, Nova Scotia. The four (4) southernmost girders in the center span were struck and significantly damaged by an excavator bucket on the flatbed of a truck travelling northbound at highway speeds. The damage to the girders beyond repair extended past the east pier and into the east side span. In addition, several of the intermediate steel diaphragms were also damaged beyond repair.
Harbourside Engineering Consultants (HEC) were sole sourced by the Nova Scotia Department of Transportation and Infrastructure Renewal to provide emergency services with respect to the repair of the bridge. HEC’s scope of work included the determination of the extents of repair, demolition design and phasing, detailed design of new bridge components, and erection phasing. The project manager/lead designer for the project was Robbie Fraser, P.Eng, while Wade Pottie, P.Eng., completed the demolition and erection phasing.
Harbourside’s Role
Harbourside developed a superstructure replacement scheme that minimized construction time and costs. The center span girders, along with the tributary deck, were removed one by one (the girders and deck were cut short of the piers to maintain support for the side spans). A transverse distributor beam (designed by Harbourside Engineering) was then installed on the east side span to transversely distribute loads as a 2m section of each girder adjacent to the east pier was removed and replaced one at a time with new girder segments via new bolted field splices. Harbourside developed an innovative step-by-step stiffness analysis of all of the existing superstructure components to determine the final conditions of the bridge’s vertical profile, and to properly camber the new girder segments ensuring proper field fit-up.
Unique Challenges
Complexities included the requirement of detailed demolition and construction phasing to ensure stability of the structure during all phasing conditions while minimizing overall Bonnie Road and Highway 101 closures. Significant analysis of existing bridge components was required during all phases of the demolition and construction.
Social Impact
The initial collision caused substantial damage to the bridge structure, necessitating an extended closure. The efficiency of Harbourside’s design and phasing reduced the time necessary for demolition and construction of the new bridge. Although a detour was still necessary for an extended period, it was vastly reduced thanks to Harbourside’s thoroughness, and detail-oriented approach.