The vessel is on its way to the Marathon Ashland Petroleum refinery in Robinson, Illinois, according to Illinois State Police Master Sergeant John Gardner. The State Police is among the agencies escorting the vessel, which is 640,500 pounds, 188 feet long and 20 feet tall.

Marathon Ashland Petroleum Project Manager Eric Mosbey said the vessel is a hydrotreating reactor that will be used to make ultra-low-sulfur diesel fuel. He said a second reactor is scheduled to arrive at the refinery next week and will take the same route.

The size of the vessel requires a lot of maneuvering and preparation. It is also very slow, only traveling about 10 miles per hour.

Gardner said nearly everyone from local law enforcement, the Department of Transportation and utility companies are accompanying the vessel.

The vessel entered Illinois on Friday. It was offloaded from the Ohio River and onto a truck by BWX Technologies.

Representatives from Texas-based Mammoet USA Inc. are accompanying the vessel because they are responsible for its transportation