The blowing of one's horn and the ringing of one's bell- when, where, why, etc. cannot be easily answered.
The best answer I can muster is: it depends.
The parameters are not complex, but they are complicated by an extensive list of exceptions, zones, types of crossings, and the list continues.
Blow thy horn ( 2 long, one short, one long ) at highway-rail grade crossings. That is the rule.
It is followed by several pages of ... unless this or that. [reference DOT.gov]
So this is what I did. I used the very cool TSW2 feature called "exploring on foot," visited every stop, and waited for a train. They come very quickly.
Two interesting observations.
1) the traffic gates are permanently down. That is to say, they never go up. No cars ever cross the tracks so I suppose it makes sense to just leave them down. Less work for the programming team.
2) No trains blow their horns. EVER. They just haul ass right on through town. Quiet as mice. This makes perfect sense. All crossings are permanently closed, no automobiles are allowed to cross, and nobody is going to code up a blowing of the horn just because I am often sneaking around on foot.
So, blowing ones horn while going over Sand Patch is a pain. Simply stated, going over Sand Patch is usually a nail-biter experience as it is, much less trying to watch out for those pesky crossings. Now that I know the "simulator" doesn't care about horns at crossings, (should I assume that?) I will no longer be making all that racket waking folks up and scaring away the animals.
I don' t know whether it affects points or achievements or levels or partridges in pear trees. I don't pay any attention to those things. I am simply hoping to drive the train with as much realism as I can manage to do.
Have a great day.