S.1125: A bill to amend the Internal Revenue Code of 1986 to provide incentives to encourage investment in the expansion of freight rail infrastructure capacity and to enhance modal tax equity.

Freight Rail Infrastructure Capacity Expansion Act of 2007 - Amends the Internal Revenue Code to allow: (1) a tax credit for 25% of the cost of new qualified freight rail infrastructure property and new qualified locomotive property; and (2) a taxpayer election to expense the cost of qualified freight rail infrastructure property (i.e., deduct all costs in the current taxable year). Terminates such credit and expensing election after 2012.