Overview: Beneath every modern city, hidden by manhole covers, drains, and ventilation grates – lies a labyrinth of tunnels, wires, conduits and pipes. They deliver power to our homes, water to our faucets, messages to our loved ones and sometimes – they even move us. Workers create the secret world beneath our feet using everything from shovels, pickaxes and dynamite to multi-million dollar tunneling equipment. The modern subterranean worker, or as they like to be called, “Sandhogs” use time tested methods as well as modern inventions, such as airlocks and computerized mapping techniques to avoid pitfalls and get the job done in the city beneath the street.