Police have arrested a woman for impaired driving after a single-vehicle collision in downtown Toronto Saturday. At 1:27 p.m., police responded to reports of a single-vehicle collision on the southbound ramp of the Don Valley Parkway to the westbound lane of the Gardiner Expressway. Police say a vehicle had flipped over. The female driver taken to hospital, though her injuries are not known. No other injuries were reported. The southbound lanes of the DVP have since reopened.