ABSTRACT
A remotely controlled hyperbaric construction machine system has been developed for caisson work, which avoids the risks of decompression sickness (DCS) and nitrogen narcosis at great depth. The machine can semi-automatically excavate the bottom of a caisson and remove muck. The system consists of an excavator (movable shovel on the caisson ceiling), equipment for loading and dumping muck, TV cameras, and a controller located outside the caisson. The caisson is sunk after the removal of muck from under the cutting edge. Most of the routine work can be done by this newly developed machine, but in the cases of repair and maintenance, technicians must enter the caisson. In such cases and if the working pressure is more than 4 bar, the technicians will breathe a nitrogen-helium-oxygen mixture (trimix). Breathing trimix requires a special or modified decompression procedure, which is now being developed.
