http://www.cnn.com/2017/03/31/us/atlanta-interstate-85-fire-collapse-cause/Started in a construction-supplies storage areaThe flames ignited in a fenced-in area where the state stores construction materials and supplies near the overpass, state Department of Transportation Commissioner Russell McMurry said.
Gov. Nathan Deal said Thursday that he had heard speculation it was caused by some "PVC products that caught fire."
McMurry initially said the materials stored under the highway were PVC pipes, but later said they were HDPE -- high-density polyethylene -- pipes. He said the conduits are used in the "traffic management, cabling, fiber-optic and wire network."
The material had been stored there "for some time, probably since 2006 or -7," McMurry said.
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Note: No mention of any vehicle.