 The idea of a tunnel connecting the Port of Miami to Watson Island was first conceived in the 1980's as a way to reduce traffic congestion in downtown Miami.Prior to the tunnel's opening, the only route for PortMiami traffic was a two-lane drawbridge that emptied out into the streets of downtown Miami.The heavy traffic was considered detrimental to the economic growth of downtown, and a planned project to expand the port's capacity threatened to increase the volume of trucks coming through.