Based on the 2nd paragraph Berkshire's 2010 letter (talking about BNSF increasing Berkshire's normal pretax earning power by 40% to about $17 billion) I think you can calculate that BNSF's normal earning power is $4.85 billion. I think Buffett paid an enterprise value of $44 billion ($34 + 10 billion of debt), implying 9x pretax earnings. Critics, including Greenwald, have focused on the fact that maintenance capex is far in excess of depreciation, so looking at the numbers on a GAAP basis doesn't make sense. I think the reason it does make sense (and the reason Buffett looks at it that way) has to do with the way the rails are regulated. The "rate base" used to calculate revenue adequacy is historical cost, rather than replacement cost. Replacement cost is much higher (in some cases 2x) historical cost, which is why depreciation so understates real economic depreciation. If the rails were allowed to earn adequate returns and this was calculated on replacement cost, much higher rates would immediately be justified. The flip side, though, is that any capex spent in excess of accounting depreciation (even if it's called "maintenance") serves to increase a railroad's earning power, because it increases the historical cost of its assets. So in all it looks like Buffett paid 9x pretax...probably not bad at all.