From its eastern end at Chaudière Falls in downtown Ottawa, the OA&PS ran south-west for a short section, following a large bend in the Ottawa River. It bent more westward south of Britannia Bay. The majority of this section of the line now lies under Highway 417, westward to the intersection with Ontario Highway 416. To the west of the highway junction, the line ran slightly north of the 417, and becomes visible again about one kilometre west of the junction, on the western side of the intersection with Moodie Drive. From here it becomes the Watts Creek Pathway for a short run to the diamond junction with CN's lines, where the line becomes active again.