Very few contractors have a crane sitting in their yard. Most of the time you have to rent one, and pay a man to work that crane. There is no way on earth you do that without having a permit approved. Here in Birmingham that's 8k a day just for the rental, plus however much a crane operator costs per day. Usually around 60 dollars an hour. So if you put a crane on site, and then take your prep work as far as you could, but than have even a couple days of delay where you're not using that crane it would cost a pile of money. Nobody wants to throw away money to the tune of $8,480.00 a day.