This work included the construction of several large bridges over the widened ravine, a curving structure over Twelve Mile Creek, and the first single-point urban interchange (SPUI) in Ontario (the only other SPUI is located on Airport Parkway in Ottawa). The original design plans for Highway 406 called for this section to follow the creek valley the full distance to the QEW, interchanging with it east of Martindale Road. Instead, the alignment was moved west of the city. Realignments to several streets in St. Catharines were completed in advance of construction on overpasses, ramps and the bridges over Twelve Mile Creek; this work was finished in late 1983.