Imagine you are on an investigation. You enter the room where activity is reported to be rampant. You get comfortable, "stamp" your recorder, and begin an evp session. Half-way through you begin to ask, "What is yo...", when a train whistle slices through the silence.
Sound familiar? It has been the experience of this group on several occasion that a train has to chime in with its low rumbles and high whistle. Why does this always happen at some "haunted" locations? Could it be due to the atmosphere getting a charge from the train rolling along the steel tracks, building friction? And do spirits use that energy to manifest in some way? Or is it a trigger for a time all but forgotten?
I haven't done enough experimenting with trains to give any definitive answer. If I had to guess, I would say that any energy wouldn't be enough to effect the conditions of some of these locations. The sound I suppose could cause some kind of trigger effect, thinking along the lines of the Singapore theory, where music or period sounds are used as a stimuli. With that being said, why are there so many trains tied to these locations? The answer is likely in the place you are investigating. Most of these buildings and homes have stood for as long as a 150 years.
A long time ago when the railroads were built from coast to coast, towns popped up and some small towns that had been already established grew all because of the railways. Having a railroad run through a town meant more business, which led to more jobs, which led to more people. So now, structures that are a reminence of the historic part of the towns will still lie near these tracks.
It may not help the haunt to the extent we would wish but it certainly adds to the town lore. We can all agree that when that whistle blows during an investigation, we'll be thinking, "another damn train".