The tunnel-boring project consisted of digging two separate bores from each end. Bids for digging the tunnel's shafts from the Brooklyn side were advertised and let the same month. Contracts for boring the tunnels from the Manhattan side were opened in May 1941. The Manhattan contract was awarded to Mason Hangar in October of the same year. A contest for designing the Governors Island ventilation building was also held, and the contract was ultimately given to the architectural firm McKim, Mead & White. The last tunneling project, a contract to dig in either direction from Governors Island until the tubes connected to each other, was advertised in December 1941.