A separate crash on southbound I-75 at South Marietta Parkway closed three left lanes. Drivers were urged to avoid I-75 in Cobb County and use U.S. Highway 41 as an alternate route. Two major crashes caused significant traffic delays on Interstate 75 in Cobb County Tuesday morning, including an eight-vehicle pileup involving three tractor-trailers. REAL-TIME SKYFOX TRAFFIC MAPI-75 crash near Delk RoadWhat we know:According to SKYFOX Traffic, the northbound crash occurred near Delk Road. I-75 South near Marietta Parkway crashMeanwhile, a separate crash also shut down three left lanes on southbound I-75 near South Marietta Parkway.