All Vehicles Carrying Passengers For Hire, All Buses Carrying Passengers And All Vehicles Carrying Explosives Or Flammable Liquids Must Always Stop No Closer Than __________ And No Farther Than __________ From Railroad Tracks?

I think the first answer is 15 feet and the second is 50 feet, but you should have a look at this document to make sure it's exactly the right answer for your question. If you are not sure you could try putting the key words 'vehicles explosives flammable liquids' in a search engine and see which results give the closest match to your question. This one is the best I could find.