Buffett looks at far more than most would even think of when purchasing companies. Just a couple of things here:
BNI owns over 32,000 miles of track. Maybe his buddy Obama is going to move on getting high speed commuter trains built in the near future? No idea, but these are the things that facilitate deals like this
OR
BNI has 10.8 Billion of debt, no idea what rate is on the books, but Warren may see huge value in retiring or re-writing that debt at a steep discount to what may be the current terms.
Maybe he is going to take it into parts, the sum of which may be far greater than what he paid.
Point is, it's not always about just owning a company so the old man can live his childhood dream of being a choo-choo train conductor.