Hi Rocker and all,
You can buy a locomotive but it won't help your scanner when you need an antenna.
Don't mind me, it's your sentence structure. (;->) Locomotives don't have strong signals, 40 watts or so into a 1/4 wave whip doesn't go far and it doesn't have to, they're never very far from a tower except in dark territory and then it's form D.
I think what you're getting at is an antenna designed specifically for VHF railroad work and there are quite a few commercial antennas available that will perform rings around ordinary scanner antennas. Look in that direction, they come with tuning instructions and you don't need sophisticated equipment, just follow the enclosed sheet.
Now there is the Traintenna designed for receive only although it could likely handle a few watts if you want the no tune option. Just put it high as possible as with any scanner antenna because height is might and don't forget some low loss coax like LMR if you have more than a few pennies to rub together, it's not cheap. Well, you get what you pay for so if you want the best, forget the rest, Al Capone's Pizza.
No joke guys, Brick NJ.
"That antenna, and other unique models that you see on locomotives, are mainly designed for survivability."