Communication in railroad operation

V. E. Thelin: One of my duties with the street railway system in Chicago is that of telephone engineer. I find that there is a particular class of work in our company in which we are at a great disadvantage; namely, that of keeping in touch with the line-construction trucks, wrecking trucks, as we use the term i. e., trucks that go out and take care of accidents on the road and with our emergency trucks that repair trolley breaks, etc. I was wondering if it is possible to use the d-c. feeder network as a conductor for carrier-wave transmission as is now being done by power distribution companies on their high-voltage transmission lines. This d-c. feeder network totals approximately 1000 mi. of single track and loops into some thirty-three substations, which possibly complicates matters.