I have homeless living behind my business, which they have expanded and have started fires. I've called to complain but they continue to move back on the railroad tracks what can I do?

Nothing if they live on the tracks but they can get in trouble for the fires if it can be proven they caused them

Call the city and place an official complaint. It will be on file in case the fires do anything. Also it will put pressure on cops to do something. Do u.have.no trespassing signs out? If so u can have them arrested if they come on the property