Transportation Funding Fairness Act This bill modifies the treatment of loans under the transportation infrastructure finance and innovation act program and the railroad rehabilitation and improvement financing program in consideration for fixed guideway capital investment grants. Specifically, the bill permits a state or other obligator to make a determination whether loans under these programs are treated as a federal or non-federal share of a project; and requires the Department of Transportation to treat the proceeds of a loan that a state has elected to treat as a non-federal share of project costs as a local financial commitment, and not treat such proceeds as non-local sources of capital and operating financing.