Highway 104 Twinning (Part 1)
Location: Antigonish, NS
Client: NS Department of Transportation and Infrastructure Renewal
Duration: 2011
Approximate Value: $2.5 M
Key Staff: Robbie Fraser, Sarah Hardy, Wade Pottie, Paule Burke,
Awards:
UPDATE:
As part of the Dexter Nova Alliance, Harbourside has received the 2025 Lieutenant Governor’s Award for Excellence in Engineering for our work on the twinning of Highway 104!
Project Description
The twinning of Highway 104 was a massive undertaking. Various projects were completed by an alliance of engineers and construction contractors working to modernize 63 km of critical highway infrastructure. As part of this monumental effort, Harbourside completed the design of the twin overpass structures at Trunk 7 intersection. This intersection was along the existing Highway 104 at St. Francis Xavier University, through Antigonish.
Harbourside’s Role
The new structures are single span, pre-stressed NEBT 1600 concrete girders spanning 30 metres. The design features fully-integral abutments founded on steel H piles. MSE walls were incorporated into the design to minimize spans and provide the grade separation between the existing trunk highway and the new highway above. The alignment featured horizontal curvature that was accommodated by using tangent girders and variable overhangs. HEC provided the detailed design of 2 alternate pre-cast deck systems that would eliminate costly and time-consuming suspended deck forming.
Unique Challenges
To address a supply and delivery issue with proprietary MSE wall systems, Harbourside provided the design (for the Contractor) of an alternate pre-cast MSE type retaining wall system that allowed construction to proceed while minimizing delays.
Social Impact
As part of the overall Highway 104 Twinning project, these overpass structures are essential in modernizing this critical transportation corridor. Twinned highways are notably safer, and more efficient than their single lane counterparts. This represents a great step forward in terms of safety for Nova Scotians, and visitors travelling the province alike.