Surging railroad tank-car orders at companies owned by billionaires Warren Buffett and Carl Icahn are defying an oil price drop that threatens to slow the U.S. drilling boom. Even with crude falling to a post-2011 low, manufacturers including Buffett’s Union Tank Car and Icahn’s American Railcar Industries Inc. (ARII) can’t meet demand. The order backlog reached an all-time high last quarter after bookings for 42,900 freight and tank cars, the most in 27 years of data compiled by Bloomberg. Producers such as Greenbrier Cos. (GBX) and Trinity Industries Inc. (TRN) are expanding as buyers seek more tank cars to move surging oil shipments and get ahead of a U.S. regulatory decision that may take thousands of units already in use off the tracks. The order buildup will ensure a good 2015 no matter where oil goes, said Michael Baudendistel, a Stifel Financial Corp. analyst. “Deliveries will be sustainable for […]