I found some info on what it was hauling.
"STORY SUMMARY: (Edmonton, Alberta) OPTI Canada Inc. ("OPTI") announced today that a specially modified version of the world's largest capacity rail car - carrying a 1.5 million lb. reactor for the Long Lake Upgrader - is anticipated to reach the Project site, 40 kilometres southeast of Fort McMurray, on Sunday, Jan. 8. The combined weight of the reactor, including fixtures, skids, and the "Schnabel" rail car, totals 2.33 million lbs. This constitutes the heaviest rail load ever to travel to Canada's Athabasca Oil Sands.
The reactor's arrival onsite at the Long Lake Project concludes a
worldwide journey by sea and rail that began in August 2005 in Kobe, Japan. The reactor arrived by ship in Duluth, Minnesota in mid-November, along with other major OPTI Upgrader components, following a journey of nearly 20,000 nautical miles.
The Long Lake Project is a 50/50 joint venture with Nexen Inc. and is
expected to be Canada's fourth and next integrated oil sands project to come on-stream. First steam for the steam-assisted gravity drainage (SAGD) portion of the Project is scheduled for later this year with Upgrader start-up in mid- 2007. The Upgrader will use OPTI's proprietary OrCrude process and commercially available hydrocracking and gasification technologies. Through gasification, this configuration significantly reduces the exposure to and the need to purchase natural gas."