Final answer:
To prefer train travel over an authorized flight for a TDY assignment, complete your authorization and CTW by comparing costs, documenting justifications on the CTW, and obtaining AO approval.
Step-by-step explanation:
If you prefer to take a train to your Temporary Duty (TDY) location rather than fly, as authorized by the Approving Official (AO), you should complete your travel authorization and Constructed Travel Worksheet (CTW) by conducting a cost comparison between the authorized flight and your preferred train travel. Document the comparison on the CTW to justify the cost-effectiveness, or provide reasoning for why it may be advantageous even if it is a higher cost. Ensure that your travel authorization reflects the actual mode of transportation you will be using along with any necessary accommodations.
It is important to get approval from your AO for the alternate travel arrangement before you proceed. This will ensure that all travel expenses are properly authorized and reimbursable, and it also helps avoid any complications with travel claims after the completion of your TDY. Always follow your organization's specific procedures and guidelines for travel authorizations and reimbursements.