450
650 bales of hay
The number of bales that can fit onto a semi will depend on the width and length of the semi's trailer and the overall cubic feet of each bale. A standard semi trailer in North America can be 8 feet to 8 feet 6 inches wide by 13 feet 6 inches high and anywhere from 28 to 53 feet long. Small square hay bales are usually 5.25 to 6 cubic feet. So if multiple the height by width, by length, you'll get the cubic feet of the trailer, you then divide that number by the cubic feet of the hay bales to figure out how many will fit in each size of trailer.
Let's do the math first. One 3x3x8 (obviously large square bale) is equivalent to 72 cubic feet. The length of the trailer would be 48 ft., width would probably be around 8 feet since it's that attached to a semi truck (the number is estimated though, you'll have to measure the width yourself), and bales would be probably be stacked around 9 feet high. That is 48 x 8 x 9 feet = 3456 cubic feet. To find the number of bales that can be fit on the trailer, divide the trailer dimensions by the large square bale dimensions: 3456/72 = 48 bales. Thus, 48 large square bales (plus or minus, depending on how high you want to stack them) would fit on a 48 ft flat-bed semi-trailer.
The interior dimensions of a 53' semi trailer is 52 feet in length and 99 inches in width. The capacity is 4050 cubic feet.
1375
70 feet
a semi flat low bed trailer is about 4 to 4.5 feet above from the ground.
3676
Assuming you are going to stack the contents the same height as they were in the semi trucks, and that each semi trailer was 53 feet long by 8 feet wide, it would take 848 square feet.
Average is 70 feet
That really depends on the length of the trailer itself. It can range anywhere from 32 feet long to over 53 feet.
4054.5