228 BULLETIN 711, U. S. DEPARTMENT OF AGRICULTURE. 
inches of the sapwood at the top of the piles ; and that a line drawn 
from center to center shall lie within the pile. 
COST OF DRIVING PILING. 
Pile driving is usually done by contract. Contract prices vary, for 
the most part with the size of the job, the distance the equipment has 
to be moved, the character of the structure, the length of the piling, 
and the character of the formation the piles are to be driven in. When 
the piling is driven in relatively deep water, the contract price for 
driving amounts to about $1.50 per pile. 
Contractors figure that the cost of driving amounts to about $1 
per pile, and that their profit should amount to about $0.50 per pile. 
The following shows the approximate daily cost per pile-driving 
crew to the contractor. 
Cost per day. 
Labor : 
Foreman i $5. 00 
Engineer 4. 00 
Loftman : 3. 00 
Boom man 3. 50 
Roustabout 3. 00 
Total 18.50 
Pile driver : 
Fuel and other supplies, maintenance and depreciation of equipment, 
interest on investment, etc 10. 00 
Grand total 28. 50 
A crew will drive from 25 to 30 piles in a day. 
LIFE OF PILING. 
The average life of piling in salt water under ordinary conditions 
is from 3 to 4 years, the maximum 5 years. Where the water is less 
salty, the life of piling is longer. For example, at or near Belling- 
ham, in the waters of Bellingham Bay, it is about 7 years. This is 
due to the fact that the Nooksack Kiver discharges a large volume of 
fresh water into this bay, hindering the rapid growth of the animal 
life that is so injurious to piling. There are other cases where the 
life of piling driven in salt water is longer than this. 
COST OF PILE-BENT TEESTLES. 
The cost of trestles is discussed in works dealing with the economics 
of engineering construction. The cost of five-pile-bent trestles of 
standard construction when built over the tidewaters of the region, 
the piles averaging about 40 feet in length, amounts to about $6 
per running foot. This is the complete cost exclusive of the rails. 
