No run of the mill mission on the Florida coast near Miami
Additionally, the front area of the machine had to be accessible at all times during the challenge off Miami to allow for tool changes, for instance. For maximum safety a bulkhead with a dive pit was developed especially for the project. Thanks to the bulkhead between the front two machine parts and the overpressure thus enabled, muck and water cannot penetrate into the machine at the tunnel face. Should high water pressures nevertheless lead to flooding, the dive pit allows safe locking into the flooded area.
In the end the safety reserves were not needed. Neither the sophisticated lock system nor the EPB mode of the HCS machine were used. The ground was highly permeable as expected, however the proper design of the cutterhead and the appropriate disc cutters enabled the customer to perform only one maintenance stop, performed under compressed air after a novative ground treatment from the TBM.