41 C.F.R. § 302-5.14 What transportation expenses will my agency pay?
Title 41 - Public Contracts and Property Management
Your agency will authorize you to travel by the transportation mode(s) (e.g., airline, train, or privately owned automobile) it determines to be advantageous to the Government. Your agency will pay for your transportation expenses by the authorized mode(s). If you travel by any other mode(s), your agency will pay your transportation expenses not to exceed the cost of transportation by the authorized mode(s).
Title 41: Public Contracts and Property Management
PART 302–5—ALLOWANCE FOR HOUSEHUNTING TRIP EXPENSES
Subpart A—Employee's Allowance For Househunting Trip Expenses
§ 302-5.14 What transportation expenses will my agency pay?

