Multiple entry lock: Six people can have their own lock and each one can open the gate alone
Each company, contractor or person has their own lock, authorized people in those companies get the key or the combo. Its so farmers, utilities etc can keep track of who comes and goes, as well if say Daves pump and go company leaves theirs off or the gate open and Franks prized goat gets out and gets pancaked they have some one to point the finger at and make pay for it.