Author: Robert Duncan Coombs

Publisher: Theclassics.Us

Published: 2013-09

Total Pages: 66

ISBN-13: 9781230462554

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 edition. Excerpt: ...brackets, riveted to the outer stiffeners of the bridge. This construction was considered advisable as the line had to cross two railroads, one heavy high-voltage line on tall towers, and several very important telephone and telegraph systems, and 1 Subsequently wrecked by a very severe sleet-storm. there was not enough space available between the existing power and telegraph systems. In making such attachments to bridges, and to some extent to any foreign structures, the construction must be accessible without interference with other interests, and at the same time be free from the probability of injury by foreign workmen. CHAPTER VIII CONCRETE POLES Wood poles had and still have certain advantages; they also have certain disadvantages. Some of the good points cannot be duplicated in concrete, but on the other hand, some of the objectionable features can be eliminated. Therefore, omitting undue enthusiasm on the one hand and any pretensions to magic excellence on the other, the matter is purely and simply one of final cost and final efficiency. It is self evident that concrete poles can be made, and it is fairly well known that a few thousand have been made and are now in service. The only remaining considerations seem to be ones of mechanical efficiency and actual or proper cost. The question of mechanical efficiency is in reality combined with that of cost. Given time-and money enough there are few structures which cannot be constructed, even by an amateur. Economical construction is another matter, and by economical is meant true economy--final economy--not merely reduced first cost. Thus, in the case of pole construction, we find that some have been built at a low initial cost but with an equally low mechanical efficiency, while...