These train/truck/helicopter/Walmart Shoppers pulls are so idiotic. The coefficient of friction is on the order or 0.006-0.010 for rubber tires- even less for harder wheels like those on a train. So to pull an eight tonne 17,600 pound) object you need 105-175 pounds of force.
The toughest part is keeping yourself from slipping as you pull - and that's why they put things like fixed ladders on the ground for the person to push against.