You will find lots of double swing/ gates have a cane bolt/drop bolt there will be a spud stone in the center of the driveway / entrance for holding one of the gates closed so they other gate can be latched closed, You will often find this stone in the center is away higher than the ground around it,from time to time you will also see a gate stop sticking up out of the ground again in the center higher than the ground around it,
I know someone who must have hit there sump drain plug off one they never remember hitting there was a oil trail from a spud stone they know they went over ,
To this day they cannot be sure the oil trail came from there car ,They had to pay for the repair ,
In the case above for what it is worth the swing /double gates were removed but the high spud stone was still in place,