TIFIA Expansion Act of 2010

TIFIA Expansion Act of 2010 - Revises Transportation Infrastructure Finance and Innovation Act (TIFIA) program requirements to make eligible for TIFIA funding any projects that: (1) are for the design, acquisition, construction, or rehabilitation of one or more transportation projects that reduce emissions of greenhouse gases or have a positive impact on traffic congestion; and (2) receive not more than 30% of their funding for capital costs from federal public transportation grant funds.

Defines "master credit agreement" as one entered into between the Secretary of Transportation (DOT) and an obligor for such projects that: (1) makes contingent commitments of one or more secured loans or other federal credit instruments at future dates; (2) establishes the amounts and general terms and conditions of such loans or other instruments as well as identifies dedicated revenue sources that will secure their repayment; and (3) provides for the obligation of funds for the loans or other instruments after certain federal requirements have been met.

Requires such projects to meet certain planning and programming requirements (as under current law) at the time that loan proceeds are disbursed or other credit assistance is provided pursuant to the master credit agreement.

Makes projects with eligible costs reasonably anticipated to equal or exceed $1 billion (mega transportation projects) eligible for federal transportation infrastructure funding.

Revises terms of secured loans and lines of credit used to finance certain transportation infrastructure projects to increase the maximum loan amount for such projects from the lesser of 33% to the lesser of 49% of the reasonably anticipated eligible project costs or (as under current law), if the loan does not receive an investment grade rating, the amount of the senior project obligations.

Authorizes appropriations for FY2011-FY2015 for such projects.