Concrete costs; tables and recommendations for estimating the time and cost of labor operations in concrete construction and for introducing economical methods of management

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...taken up in detail on page 272. The unit times are discussed below and the various items are taken up more in detail on page 291. ACCURACY OF METHODS OF UNIT COST Costs of hand-mixing are frequently tabulated in print, but almost invariably they are stated in such a way as to be nearly useless for estimating the cost of other jobs. This is because important items of information are missing or else because the conditions do not cover the operations on the other jobs. This point is illustrated in Chapter IV, page 64, where an illustration is given showing how simple changes in conditions so affect the cost of labor that in one case it may be $2.51 per cubic yard of concrete as against $0.83 in another case with the same 'gang and layout of work. Such variations are illustrated even more strikingly in Table 56, page 318. A careful statement of local conditions is seldom made in published literature, and consequently the wide variations in costs on different jobs are ordinarily charged to a difference in the ability of the men. While this personal element, which can only be allowed for by estimation, is of importance, the largest part of the variation, as a matter of fact, is due to causes readily explainable and which can be foreseen and allowed for. It is evident that, to be of value, unit costs must be so presented that they can be used directly, and while it is impossible in any tables to allow for all possible differences in conditions and in relative ability of labor--any more than in estimating the cost of materials it is possible to figure in advance the exact quantities or to determine the exact prices that must be paid--labor costs can be figured by experienced men who have the proper unit costs and know the conditions under which the work is to be pe...