Abstract Manager

In Prince Edward Island (PEI), Provincial Highway Route 2 is the economic backbone for traversing the Island from Tignish to Souris. As part of the highway, the Souris Causeway runs along a sand spit that separates an estuary from the Gulf of St Lawrence. The Causeway is a significant transportation link to the Town of Souris and communities beyond, popular tourism destinations, and the ferry terminal to Quebec’s Magdalen Islands. Erosion and flood hazards are severe, heightening the risk of closure of this vital transportation link.

In 2018, the PEI Department of Transportation and Infrastructure (DTI) successfully built two offshore sandstone reefs as a pilot project for erosion mitigation. Following this pilot, subsequent shoreline protection was built in 2025 and 2026 using a hybrid combination of structural and nature-based features on both sides of the vulnerable causeway. These included two additional sandstone reefs, terminal groyne structures, and beach fills stabilized by rock sills to support the re-establishment and growth of a tidal wetland. These options were selected based on thorough analyses of hydrodynamic and sediment transport processes developed from historical observations and numerical modelling.

The success of this innovative work has garnered inspiration and support for similar coastal engineering projects at other locations across PEI. Post-construction monitoring is ongoing at the Souris Causeway to inform DTI’s long-term adaptive coastal risk mitigation plan along this critical transportation link.