LOCATION. 19 



the assistance of Figs. 1, 2, and 3, or computed in accordance 

 with the general principles before given. 



"Momentum" or velocity grades may be used with due cau- 

 tion to avoid increasing rate of ruling grades, or to avoid large 

 construction expenditures otherwise necessary. In all such 

 cases train stops, grade crossing and limiting or dangerous 

 curvature must be avoided. 



Velocity grades requiring freight train speeds in excess of 30 

 miles per hour must not be used, nor should such grades be 

 laid out for speeds in excess of that obtainable under ordinary 

 working conditions. 



MAINTENANCE AS AFFECTED BY LOCATION. 



The cost and difficulty of maintaining track and road bed 

 may be greatly affected by the general characteristics and 

 local details of the selected route, and all such conditions 

 should receive careful consideration during the location of 

 the route. 



The greatest differences may exist, even between the two 

 sides of the same valley, as one side may be subjct to contin- 

 gencies of drifting snow, slides, cloud bursts, stream encroach- 

 ments or "washouts," from which the other side is wholly 

 free. Conditions of greater shade, due to forest or bluffs, may 

 cause longer duration of snow, frost and moisture, or local 

 peculiarities of soil, and the character and number of lateral 

 streams to be crossed may all contribute towards the increased 

 cost of maintenance. 



Additions to cost of maintenance arising from faulty details 

 of "construction," may not be properly considered in connec- 

 tion with the subject of "Location," unless resulting directly 

 or indirectly from the character of the location, such as un- 

 necessary increase in number and length of bridges, grade 

 crossings in lieu of possible under or over crossings, faulty 

 arrangements of grades, affecting yard and station expenses, 

 and other items of like character. 



All additions to operating expenses, arising from such 



NOTE. The table of "Velocity Heads" and the economic values given 

 for "Distance," "Curvature," and "Rise and Fall," are derived from 

 WelHnctOE's "Economic Theory of Location;" the values have been pan 

 Italized at 6%. P " 



