Railroad expert witnesses may give opinions regarding railroad accident reconstruction, railroad accident investigation, train wrecks, and railroad safety. News.nationalgeographic.com reported that the oil train tragedy in Lac-Mégantic, Quebec, involved crude oil tankers that decoupled, slid downhill and exploded. The train was parked and unmanned when 72 tankers caused the fire and explosion near the Maine border. The oil was being conveyed from North Dakota’s Bakken oil fields to a New Brunswick refinery.