Sangster Bridge Demolition
Location: NS, Canada
Client: Dexter Construction
Duration: 2010
Approximate Value: $1.2 M
Key Staff: Robbie Fraser, Greg MacDonald
Project Description
In 2010, Habourside was working with Dexter Construction on the demolition of the Sangster Bridge. The original demolition plan proposed providing a temporary in-water support and lifting the bridge out in two sections. This was due to the limited crane sizes available (or economically viable). This original demolition plan was not provided by HEC.
Harbourside’s Role
Harbourside instead provided a value-added alternative to the demolition of the existing through truss bridge, saving both time and money for our client. HEC quickly identified that, due to the light framing of the diagonal web elements of the truss significant reinforcing would be required to address reversal in axial loads resulting in large compression loads in extremely slender tension members. Harbourside developed a demolition plan that supported one end of the bridge on modular barge units owned by the contractor allowing the bridge to be floated to one approach and demolished in sections on land. HEC conducted a full analysis of the bridge during all phases of the demolition. In addition, Harbourside provided the detailed design of the supports on the barges and connection to the existing bridge structure. Finally, Harbourside conducted a full floating stability analysis for the barges while supporting the bridge.
Unique Challenges
The Sangster Bridge Demolition project is a prime example of the approach Harbourside uses on all of the projects it undertakes. In a constrained environment, HEC developed an Innovative bridge demolition technique that proved both more rapid and cost effective than the original proposition. The existing through truss bridge was demolished successfully and with betters results than originally anticipated.
Social Impact
The Sangster bridge was located on a popular route throughout Hants County. Its demolition and subsequent replacement were part of a much-needed redevelopment of infrastructure in the region. This redevelopment goes a long way to improving travel safety throughout the area.