Well, David, in the post-war years there were only steam trains and it was common practice for local councils to locate allotments alongside the tracks. What the quality of the vegetables was, I don't know. Alongside a railway would not be my first choice of a location for a vegetable garden but I woud guess that yur tourist line will carry much less traffic than the former east coast main line did.

veg will grow in most sites, go for it steam trains might help see off some bug's and I do not think that the amount of tourist trains will bring to much from the diesel ones to stop them going well, good luck.

In the States, the railways spray the ground along the tracks with powerful herbicides to keep weeds down. It may only be safe to plant veggies if the plot drains toward the tracks.

Would some container veg in a different location be an option?