My understanding, for what it is worth, is that most states have statutes on the books going back many years requiring railroads to clear growth so many feet on both sides of their right of way to prevent fires. In addition, the exhaust systems on heavy diesel equipment (including spark arrestors) require PERIODIC MAINTENANCE to prevent carbon build up which results in the release of burning embers and subsequent trackside fires. I believe a series of fires earlier this year were linked to the movement of a train.
An example from the General Laws of Massachusetts;
Chapter 160: Section 235A Clearing of inflammable material along right of way
Section 235A. Every railroad corporation shall, between April first and December first in each year, keep the full width of all its locations, to a point two hundred feet distant from the center line on each side thereof, clear of dead leaves, dead grass, dry brush or other inflammable material, and shall not at any time leave any deposit of fire, hot ashes or live coals upon its locations in the immediate vicinity of woodlands or grass lands, and shall post in stations and other conspicuous places within its location and right of way such notices and warning placards as are furnished to it for the purpose by the director of the division of forests and parks in the department of environmental management; provided, that this section shall not prohibit any railroad corporation from piling or keeping upon its location or right of way cross-ties or other material necessary for the maintenance and operation of its railroad.
