A Rock Island woman was killed Saturday morning when an 18-wheeler slammed into her car while she was stopped at a red light on the main highway through Sparta.The woman, Jeanne Mannes, 76, was killed on impact when she was hit from behind by a 2012 Freightliner tractor trailer driven by Curtis Carter, 32, of Tullahoma.The accident happened on Highway 111, better known in McMinnville as Sparta Highway, near the Taft Church Drive intersection. Authorities say Mannes had come to a stop in her 2005 Toyota Camry in a southbound lane to wait for a red light to change. It was while stationary, she was hit from behind by the tractor trailer.The vehicles both came to rest in the grass off the southbound lanes.