Why are the tunnels filled with water? It has occurred to me that since the water in the tunnel leached alkali from the concrete and thus created a corrosive solution, the corrosion could be prevented by removing the water. In Philadelphia there is a dry tunnel carrying fifteen 13 kv lead sheathed power cable lines and three 66 kv pipe type cable lines. The cables are in open trays and the pipes are also exposed. Any tendency for the cables or pipes to be corroded by solutions dripping on them can be observed and prevented by deflecting the drip with a baffle.
The tunnels are filled with water to permit the maximum loading of conduits and to reduce the amount of sheath expansion due to migration of cable impregnating compounds. The load capability of the conduits would be reduced approximately 50 percent if the water were removed from the tunnels....
