You need to paint a better picture, it's pretty foggy, saying rural and then residential neighbors. Are the neighbors 10 acre mini estates or have land with each home or are the subdivisions?
The RR tracks issue depends on its use, frequent, seldom?
What town is this near? Cotty(ie) College is an all girls private college in a small town near here, if you go ten miles away, it's pretty rural and has scattered homes with acreage so sounds similar.
I'd tend to not go with a warehouse idea, I doubt there is a spur available along rails in rural areas where higher speeds are used and the cost could be more than the land value. From rail to house and ultimately to a truck, if it were an interstate with ingress/egress that might work, sounds like your traffic flow is limited with a median...how far to turn backs? Warehouses tend to be near populated areas for distribution, so tenant/owner possibilities may be limited.
Ten miles out is not so far away for a subdivision, 40 acres might get you 12 or 13 3 acre tracts, depends if sewer is there or you need to have septic. Another limitation is water districts and having a well. State law may apply to water supplies and sewage treatment with a subdivision. Guessing, I'd say from the rural nature in location that a subdivision of quarter acre lots might not be marketable, probably one acre lots and 2,000 to 3,000 sq ft homes. A subdivision of high efficiency solar capable smaller homes might work, depends on your market, something more unique not wild.
I guessing to you are looking for a use without much more investment. That takes the subdivision out.
Might have a light industrial use, heavy equipment supply/repair, tractors, farm machinery, welding shop, trailer manufacture. Depends on regulations, you might get by with a metal building and gravel lots.
Really, without more information about the location, town, highway access and terrain, we are shooting in the dark. :)
Bill Gulley, General Real Estate Academy