It never hurts.

I would suggest sending a letter to the corporate affairs office of the railroad, or you may find another contact on the railroad's web site.

Here's a sample letter, adapted from one I actually sent once (and received permission):

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We are requesting permission to use [describe mark] on three freight cars. blah, blah. The uses of the mark will be solely in the context of historic interpretation We do not intend to sell merchandise using this mark, nor will we allow such merchandise to be sold on our property unless it is properly licenced.

We would be grateful for permission to use this mark. Please advise if you
have any additional restrictions for the use of the marks.
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You have a real mixed bag here. In previous discussions here, it seems to depend on which railroad you are talking about.

The Union Pacific is real real picky about who used their name and logos. They are even going after the model train manufactures.

I suspect that if the line is a Fallen flag, you will not have paroblems, but even there I visited the Danbury Railroad Museum and saw a Boston And Maine steamer which they told me was denied permission to use the B&M name by modern Guilford Industries.

So Iike I said, it all depends.

Ted Miles