The Port of Miami Tunnel project is a public/private partnership project being constructed by MAT concessionaire jointly with the Florida Department of Transportation, the City of Miami, and Miami-Dade County. The project consists of the construction of a new underwater tunnel connecting Watson and Dodge Islands near downtown Miami, in conjunction with the widening of the MacArthur Causeway bridge and the reconfiguration of roadways on Dodge Island to expedite traffic moving to the cruise and shipping terminals. This project is great because its main goal is to allow traffic, including large numbers of truck traffic, to get from the interstates to the port without traveling on the surface streets of downtown Miami. This will reduce congestion in downtown Miami, as well as contribute to the development of those areas surrounding the port.
This project is significant in many ways, foremost of which is that the tunnel boring machine (TBM) being used to dig the tunnel, named Harriet, is the largest TBM in the US (at 42.3 ft in diameter). Harriet was built in Germany and reassembled in Florida. On July 31, 2012, Harriet completed the first leg of its journey beneath Biscayne Bay, breaking the ground on Dodge Island. On May 6, 2013, Harriet finished its return trip, breaking the ground at Watson Island. A tunnel was chosen over a bridge as it would not be possible to gain the vertical clearance required for the cruise ships to fit beneath a bridge in the short distance over Biscayne Bay between Watson and Dodge Islands.
The widening of the MacArthur Causeway bridge allows for the construction of new ramps to move traffic into and out of the tunnel, as well as to add pedestrian facilities from MacArthur Causeway down to the roadway below, where people like to fish.
The majority of the roadway systems on Dodge Island were redesigned in conjunction with this project, to facilitate traffic movements created by the construction of the tunnel. The construction of the new bridge on Dodge Island is required because of these new traffic movements and will help traffic more easily access the cruise terminals.