Route 115 begins at St. Mary's Road and runs eastward through Old St. Boniface as two one-way streets: Goulet Street for westbound traffic, Marion Street for eastbound traffic. The streets join at their intersection with Rue Youville just west of the Seine River, and the two-way road continues as Marion Street eastward to Lagimodiere Boulevard. The route jogs north on Lagimodiere for approximately 450 meters before continuing eastward as Dugald Road, becoming Manitoba Highway 15 as it passes by the Perimeter Highway.