Fit out of the new Port of Miami Tunnel is now underway following the recent breakthrough on the second tunnel boring machine (TBM) drive on the project.
Breakthrough on the project means that main contractor Bouygues is on course to complete the scheme next year allow the 16,000 vehicles that use the port each day to directly access the interstate and bypass the city centre.
The TBM used to drive both 12.86m diameter, 1.2km long bores was specially developed for the project to cope with the challenging ground conditions by Herrenknecht. The earth pressure balance machine – named Harriet – was designed to deal with the soft but stable ground at the tunnel entrance and exit, as well as the porous limestone with high water pressures in the middle of the drive.
According to Bouygues project manager Louis Brais, the scheme was one of the most technically challenging tunnelling projects undertaken in the world to date.
Work on the tunnel drive started in November 2011 with the first bore completed in July last year. The TBM was turned round to drive the second tunnel with construction restarting in October 2012.