David Winters, CEO of Wintergreen Advisers, comments on Buffett's recent purchase of shares in Burlington Northern Santa Fe in this article. He's the only one interviewed for the article that actually understands Buffett's motivation. The "'unduplicable franchises' protected by huge costs of entry" is likely the key characteristic attracting Buffett (with Munger's guidance) to railroads. I guess I'm not the only one that tries to aquire the four railroads when playing Monopoly.