If you're not to concerned about accuracy: Typographers would call this a serif font. Perhaps a slab serif. Go to a free font site, and just start looking around.
Have a look here. You're probably looking for a 'best match', as many railroads used their own typeface design. If your editing program allows for it, letters may be stretched horizontally, giving a broader range of typefaces that come close.
Another way is identifying by sight using
this website.