My understanding is that this is actually one of those bizarre instances of "life imitating art".

The first depiction in fiction of someone being tied to a railraod track seems to be the 1867 play Under the Gaslight by Augustin Daly. A complete text of the play is available here, in the public domain: http://victorian.worc.ac.uk/modx/assets/docs/pdf/Vol81iUnder.pdf

However, there are a couple of instances from the late 19th and early 20th century of people actually being killed by being tied to railroad tracks, as recounted in this Straight Dope column from 2007. However, the column also suggests that:

it probably happened in fiction first, and its metaphorical content is open to debate.

The earliest real-life incident I could find was from 1874, when on August 31 the New York Times reported that a Frenchman named Gardner had been robbed and tied to railroad tracks. He managed to loosen all the ropes but the one that secured his left foot, and the train cut off his leg below the knee. Though he survived to describe the attack, he soon died of his injuries.

There are other examples, including cases involving a kidnapped 13-year-old boy (1881), a 40-year-old mechanic (the article actually uses the word "dastardly" to describe the crime), a college freshman (part of a 1905 fraternity initiation; he died), a 10-year-old boy (1906), and a 19-year-old man (1907).

But all these may well have been copycat crimes, in a sense, as some very widely known fictional examples predated them. The first American work to feature "the railroad scene," as critics and courts came to call it, was the short story "Captain Tom's Fright," which ran in the March 13, 1867 issue of the Galaxy magazine.

Furthermore, the columnist goes on to suggest (totally unsupported) that the initial popularity of these scenes may have been a pop-cultural manifestation of common anxieties regarding rail travel and steam engines in general, which were still a relatively new technology at the time.