60 BELL SYSTEM TECHNICAL JOURNAL 



but the observance of most rigid precautions does not entirely pre- 

 clude the possibility of hazard to the men when handling the heavier 

 poles. Further, the pole locations are not always such that a con- 

 siderable number of men with pikes can properly distribute them- 

 selves about the pole so as to complete the raising and lowering oper- 

 ations in a reasonably safe and efficient manner. 



Earth Boring Machines 



One of the slowest and most difficult physical tasks connected 

 with outside construction work is that of digging pole holes. It is 

 estimated that upwards of 1,000,000 holes must be dug annually to 

 accommodate the poles erected in new locations, and those replaced, 

 moved and reset in the Bell System. Under soil conditions reason- 

 ably free from obstructions a man can generally average about three 

 holes per day with perhaps five to six as a maximum under ideal soil 

 conditions, while in more difficult digging one or possibly two holes 

 may represent a good average day's work. It probably requires 

 somewhere in the neighborhood of 3,500,000 man-hours per year 

 simply to dig pole holes. 



For a number of years the availability of a practical pole hole 

 digger has been the objective of telephone linemen. Development 

 work has progressed rapidly during recent years and the high point 

 of perfection which has been reached in automobile truck design and 

 performance has greatly simplified the adaptation and increased the 

 practicability of the boring apparatus. It is of interest to note in 

 this connection that the solution of the problem comes at a time when 

 there is a pronounced shortage of common labor. 



The construction in 1914 of that portion of the transcontinental line 

 extending across Nevada, marks the first really economical application 

 of a machine to bore pole holes. In about 1917 the need for labor 

 relief led to renewed activity in connection with adapting the funda- 

 mental principles of the original boring apparatus to machines suffi- 

 ciently flexible to meet the general and rather exacting requirements 

 of telephone work. 



Fig. 7 shows one of the latest developments in earth boring ma- 

 chines, which is cleancut and rugged. This machine is mounted 

 upon a 4-wheel drive truck and is otherwise specially equipped which 

 enables it to reach practically any location where it is necessary to 

 bore holes for the erection of poles. As a matter of fact it has been 

 demonstrated that these machines are able to reach approximately 

 95% of the pole locations. Further, the machine being equipped 



