A manhole cover is a removable plate that forms a lid over a manhole opening to avoid someone or something from dropping in, as well as to keep unwanted people and materials out. Manhole covers can be traced back to the time of ancient. This makes them cheap, solid, and heavy, weighing in at more than 50 kilograms on average. When traffic runs over them, the weight continues to hold them in place, making it impossible for unwanted individuals without the proper means to lift them.