80 OVERHAUL. 



We see, therefore, that the contractor ordinarily hauls the 

 earth just as short a distance as he possibly can before dump- 

 ing it in the fill, and it is but just and right that he be per- 

 mitted to do so. 



There is a method of figuring overhaul that is sometimes 

 advocated (see letter to Editor Engineering News, Mar. 14. 

 1891, signed "W. R. H.") wherein the center of mass of the 

 whole cut and the center of mass of the corresponding fill are 

 ascertained; then having found the distance apart of these 

 centers of mass the free haul of say 500 f\. is subtracted. This 

 difference is called the overhaul. Obviously this method gives 

 a greater average overhaul than where the common method 

 about to be described is used, and unless clearly specified in the 

 overhaul clause this method should not be used. In Engineer- 

 Ing News, of issue just referred to, there is described and illus- 

 trated a method of estimating overhaul which is simple, legal, 

 ftnd as exact as can be desired in practice. 



The method is described in a letter to the Editor of Engi- 

 neering News as follows in full: 



Sir: In your issue of Jan. 31, a method of estimating overhaul by a 

 profile of quantities, by S. B. Fisher, is published. I have used a 

 method somewhat similar to that, which is illustrated in the accompany- 

 ing diagram (Fig. 1). This method consists in plotting the quantities 

 in the cuts and fills on ordinary profile paper, and preferably on the 

 same paper on which the ordinary profile is plotted, using the same hori- 

 zontal scale, and placing the stations for the quantity profile directly 

 above or below those on the ordinary profile, as in Fig. 1. These quan- 

 tities are final quantities calculated from the construction cross-section 

 aotes. Each cut and fill is plotted separately, cuttings in red (= heavy 

 solid lines in Fig. 1), and fills in blue (= heavy dotted lines in Fig. 1); 

 the origins or zero points being at the stations or plusses where the cut 

 changes from cut to fill occur (= grade points). 



The total quantity of cut or fill from a grafle point up to a given sta- 

 tion is plotted opposite that given station, so that in the curve of quan- 

 tities thus made, an ordinate at any station represents the total quantity 

 In the cut or fill the grade point (= 0.0 cut) up to that station. 



By plotting backward (from the last grade point toward the first grade 

 point of a cut) in the same manner we obtain two curves symmetrical 

 about a horizontal line through their point of intersection, and which in- 

 tersect in the center of gravity (strictly speaking, center of mass) of 

 each -cut and fill. 



The method of using this profile of quantities can be best understood 

 toy referring to Fig. 1. The cut from Sta. 499 + 30 to Sta. 504 will b 

 hauled into the fill from Sta. 604 to the bridge opening at Sta. 510 i 75. 



