If I am using 50' or longer, 300 times 50 = 15,000 or longer, not including locomotives.I don't know how long 300 cars is in feet, but if you see any monster 12,000ft trains, they can cause an unmistakable traffic nightmare if its a sluggish kind of day. I've seen some 10,000 and 11,000ft monsters, but the 12,000ft MNPHK is elusive....