302 TfNXKMM; 



Ofen tunnel Austrian method $93.19 per lin. ft. 



Dorremberg tunnel Belgian method 86.08 " " ' 



Stafflach tunnel English method 91.69 " " " 



The Martha and Merten tunnels, excavated through soft 

 ground by the Austrian and German methods respectively, 

 cost $87.95 and $87.55 per lin. ft. respectively. In the exca- 

 vation of the various sections of the tunnel for the new Croton 

 Aqueduct in America, the following prices were paid : - 



Excavation of heading $8 to $10.00 per cu. yd. 



Tunnel in soft ground 8 to 9.00 " " " 



Tunnel in rock 7 to 8.50 " " " 



Brick masonry 10.00 " " " 



Timber in place 40 per M. ft. B. M. 



It is the practice in America to include the work of hauling 

 under excavation, but not to include the strutting, which is 

 paid for separately. In some cases only the market price of 

 the timber is paid for separately, the cost of setting up being 

 included in the price of excavation. The writer prefers the 

 European practice of including the total cost of timbering 

 under excavation, since the two operations are so closely con- 

 nected, and since the contractor employs the same timber over 

 and over again. Knowing the dimensions of the several mem- 

 bers of the strutting, it is a simple, although somewhat tedious, 

 process to calculate the total quantity required. An idea of 

 the quantity of timber required for strutting in soft ground 

 may be had from the data given on page 50. The quantity 

 will decrease as the cohesion of the material penetrated in- 

 creases, until it becomes so small in hard rock-tunnels as to cut 

 very little figure in the total cost. 



The cost of hoisting excavated materials through shafts 

 depends upon the depth from which it is hoisted, and upon the 

 character of hoisting apparatus employed. The following table, 

 showing the cost of hoisting for different lifts and by different 

 methods, is given by Rziha, the cost being in francs per cubic 

 meter : 



