 At the Laurentian interchange, in Montreal, the Abitibi route (Highway 66, Route 117, A-15) rejoins the main TCH line.The TCH then follows Autoroute 25 southbound, crossing the St. Lawrence River through the Louis-Hippolyte Lafontaine Bridge–Tunnel, and proceeds northeast on Autoroute 20 for to (across from Quebec City).East of , the Trans-Canada Highway continues on Autoroute 20 following the south bank of the St. Lawrence River to a junction just south of , northeast of .