This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
A combination of steel, concrete, and wooden piles is known as the Cushing pile foundation. A cluster of piles is driven so that it may be surrounded by a wrought-iron or steel cylinder, which is placed over them, and which is sunk into the soil until it is below any chance of scouring action on the part of any current of water. The space between the piles and the cylinder is then surrounded with concrete. Although the piles are subject to decay above the water line, yet they are so thoroughly surrounded with concrete that the decay is probably very slow. The steel outer casing is likewise subject to deterioration, but the strength of the whole combination is but little dependent on the steel. If such foundations are sunk at the ends of the two trusses of a bridge, and are suitably cross-braced, they form a very inexpensive and yet effective pier for the end of a truss bridge of moderate span. The end of such a bridge can be connected with the shore bank by means of light girders, and by this means the cost of a comparatively expensive masonry abutment may be avoided.
*Condensed from Engineering Record, February 22, 1908.