218 EARTHWORK 



free-haul limit. The allowance is made per cubic yard for 

 each station of 100 ft. 



Computation of Haulage. If, in the profile shown in the 

 accompanying illustration, the material of the cut is deposited 

 in the position ODN, the total haulage that is, the sum of all 

 products obtained by multiplying each volume by the distance 

 through which it is hauled will be 



volume CMO X ZZ' = volume OND X ZZ' , 



G and G' being, respectively, the centers of gravity of the 

 cut CMO and the embankment ODN. 



But, as the short hauls are not averaged against those which 

 are beyond the limit of free haul, the contractor is entitled to 



extra compensation when the distance CD exceeds the limit 

 of free haul. To calculate the overhaul, two points A and B 

 must be found whose distance apart equals the limits of free 

 haul and which are situated so that the volume AKO equals 

 that of OBL. The remaining part CMKA, which is to be 

 placed in the position BLND is to be considered as overhaul. 

 If g and g are, respectively, the centers of gravity of these 

 volumes, and V the cubical contents of each, then the haulage 

 of this volume is VXXX'. Of this, the distance AB is to 

 be hauled free of charge, and the overhaul is therefore 



Since V = volume of CM KA = volume of BLDN, the simple 

 rule for figuring overhaul is to compute the total haulage of 

 the cut CM KA to the point A and the total haulage of the fill 

 BDNL to the point B, and then add the results. These 

 values of VXXA and VXX'B are found as follows: 



