National Geographic : 1911 Feb
0 I-IO'10 N GENERAL VIEW OF UPPER LOCKS AND FOREBAY, GATUN, LOOKING NORTH, IN1909 Four duplex cableways span the locks, with steel towers 85 feet high and 800 feet apart. Theypick upfrom thedelivery carthebig buckets of concrete, send them out on the aerial trams, and lower them where required. One man operates acableway, controlling allthe movements by switches located on a platform on each head tower. In addition to delivering concrete inthe locks, thecableways areused to lift material from the lock site and dump it by an aerial dumping device, to handle forms for the concrete work, and tohandle theparts of the gates and the gate-operating machinery. The carrying cable is a locked steel wire 2'4 inches indiameter, itscarrying capacity being considerably over 6 tons. Twenty trips an hour can be made on each cableway. The greatest lift is 170 feet. The towers aresetontracks on which they can be easily moved along the lock site as the work progresses.