Below is the excerpt from the CBA. I have NEVER gained nor did I have to for train travels subjected to any $100/200 limits. Train travel away!

Surface transportation of reasonable expense between commercial locations, or between a residence and the field airport/FedEx field operations area, requires prior approval by a pilot’s ACP. Such approvals may be granted on an on-going basis.

Intent: ACP approval will not be required for qualifying ground transportation up to $100 per occurrence. Deviation ground transportation greater than $100 up to $200 must have specific ACP approval. Deviation ground transportation for amounts greater than $200 must be approved by a pilot's RCP. In both instances, a copy of the e-mail documenting the ACP/RCP approval must be included with the pilot's expense report. Approvals may be granted on an on-going basis. It is not the intent of this policy to allow extravagant travel when reasonable, lower cost transportation is available.
A pilot who is assigned to initial, transition or upgrade training away from his base may elect to drive his vehicle to the training location. In this event, the AAA calculated mileage, round trip from the pilot’s permanent residence to the training facility at the current IRS mileage rate shall be allowable/reimbursable. (e.g., Training in DFW and a pilot drives his car to and from).
Trains
Travel by train or subway are allowable/reimbursable expenses to the same extent air travel or surface transportation expenses would have been allowable/reimbursable.