220 



EARTHWORK 



If lc. is paid for each cubic yard hauled one station in the 

 overhaul, find the total allowance for overhaul if the shrinkage 

 of the material in the embankment is 10%. 



SOLUTION. The foregoing formula must be applied to each 

 of the prismoids. 



1. For the Cut. Following is the tabulation of the end areas 

 and volumes; the end areas are the algebraic sums of one- 

 half the plus and minus areas found in the tabulation on pages 

 210 and 211, and the volumes are obtained by applying the pris- 

 moidal correction to the volumes in column 4 ('>) of that table. 



Sum = 4, 873 



Sum = 6,247 



The numbers in the fourth column are the distances from 

 the middle sections of the prismoids to the point A, at Sta. 

 129, at which point the free haul begins. Thus, the middle 

 section of the prismoid between Sta. 126 and Sta. 127 is at 

 Sta. 126+50; the distances from this section to Sta. 129 is 

 (129 - 126.50) X 100 = 250 ft. Similarly , 'for the prismoid between 

 Sta. 127 and Sta. 128. m = (129 -127.50) X 100= 150 ft. 



I a' a 



The value of -X for each prismoid, is given in the 



6 a'+a 



fifth column. Thus, for the first prismoid, 

 100 157.4-439.4 



X = -8 ft. 



6 157.4+439.4 



For the second prismoid, 



100 439.4-484.3 

 6 439.4+484.3 

 and similarly for the others. 



