To alleviate traffic congestion and safety concerns on the Gardiner Expressway in Toronto, Ontario, Canada, the City of Toronto has elected to implement scheduled closures for the two on-ramps since early 1970s. This study investigates the traffic impacts of the daily on-ramp closures at Gardiner Expressway and Jameson Avenue. The average changes to traffic flow variables such as traffic volume throughput due to the ramp closures are computed quantitatively. Results show that ramp closure has resulted in smoother traffic flow and higher travel speed but not higher traffic throughput on the expressway. Ramp reopening causes a spike in speed variations as measured by upstream detectors. The network performance metrics (vehicle hours traveled, vehicle kilometers traveled, delay, and travel time) are computed and analyzed to determine the performance benefits of the ramp closures. The travel time saving in the area due to the ramp closure is estimated to be 225 vehicle-hours per day.