The Callahan Tunnel, officially the Lieutenant William F. Callahan Jr. Tunnel is one of four tunnels, and one of three road tunnels, beneath Boston Harbor in Boston, Massachusetts. It carries motor vehicles from the North End to Logan International Airport and Route 1A in East Boston. Ordinarily, this tunnel is only used to carry traffic out of the city, and with the completion of the Big Dig it only collects traffic from I-93 southbound (right after traffic merges from Storrow Drive) and downtown Boston. There is no toll in this direction.