Material, supplies and minor equipment used up during the prosecution of the work may be listed as:
Repair parts, or small shop supplies necessary to the maintenance of machinery in working condition; also small tools, as picks, shovels, rope, blocks, small hardware, lumber, feed for live stock, etc.
No hard and fast line can be drawn between these items and those larger and more permanent items considered under the head of plant.
Since one class of subsistence has been mentioned, brief consideration may be here given to subsistence of labor. While camp buildings were included under the head of plant, the actual operations of boarding the men and furnishing commissary supplies may usually be omitted from estimates. Such operations may be left to themselves, i.e., considered as separate enterprises which will be self-supporting or even yield a small profit.
Steel (as reinforcing steel)
Pip? (steel, cast iron, wrought iron, vitrified, tile)
Operating machinery, etc.
Of the foregoing items cement is sometimes paid for as an item in the contract and sometimes not. In any case the cu. yd. of masonry and barrels of cement required per cu. yd. of various kinds of masonry are known, and cement prices can be readily obtained on inquiry. The simpler items of lumber, reinforcing steel or pipe can be readily estimated in quantity and prices obtained from current material price lists in the technical press.
When estimating specially designed pipe, valves, gates, operating machinery, etc., it becomes necessary to design the same and produce plans in sufficient detail so that they may be submitted to manufacturers and serve as a basis for bids. Such special features should be treated as a separate contract, the plans detailed by the owner's engineer and bids requested from manufacturers in those lines.
That the contractor for the main work should be required to burden himself with such a mass of unfamiliar detail in the short time usually allowed him in which to prepare his bid will result in an unsatisfactory treatment of the design or a very high price to cover contingencies. Such a requirement is altogether foolish and an economic waste. Preliminary or tentative plans furnish a sufficient basis for a bid per ton for setting metal work, leaving the details to be worked out later. In preparing such detail designs and obtaining bids from manufacturers, there are two extremes to the course open to the owner's engineer, either one about as much to be avoided as the other. He may accept manufacturers' designs and specifications without question, or he may ignore them entirely. If manufacturers' stock does not meet the conditions, if "made by the mile and sawed off to order stuff" does not always fit the case, it happens as often that some slight adaptations or immaterial changes in some other feature will render available the product of some manufacturer who has spent years in bringing that product to perfection. If entire surrender of his function may be called a sign of incompetency, an obstinate insistence upon it, to the extent of ignoring the manufacturer's experience and stock, may be equally such.
After providing for plant and materials the next step is to estimate the cost of the labor required to perform the various items of work. To do this intelligently it is necessary that the main operations should be analyzed into their elementary parts and the labor estimated for each part. Thus laying masonry may be divided into producing a certain number of cu. yd. of large stone, number of cu. yd. smaller stone or waste for the crusher, crushing stone, producing sand, hauling, storing and handling cement, assembling certain materials at mixer, mixing, transporting to the point where the masonry is built, laying the masonry, etc. Certain of the above operations, as quarrying, may be further subdivided into drilling, loading and shooting, breaking or splitting to size, etc.
For certain operations the output or product will be almost directly proportional to the number of men employed, and prices per unit of output may be assigned for the particular circumstances and according to the experience and judgment of the estimator. Certain other operations or parts of operations, however, are practically an expense in proportion to time regardless of output, so that the cost per unit quantity varies inversely and as widely as the rate of progress. This being so, the various rates of progress between the beginning and end of the work, and the number of men required at each, should be estimated as closely as may be. Then a total duration of the work should be arrived at, and the cost of that operation should be estimated for the total time. That certain items, as for instance power-house operation, are distinctly of this nature would be evident to the most casual and inexperienced consideration. Certain other operations are less obvious, and all of them should be carefully scrutinized. The operation of a cableway costs as much for one derrick as for three or four.
A derrick requires an engineer for work at one-tenth its capacity as well as at full capacity. A given crushing and mixing plant will require just about the same number of attendants for an output of 100 cu. yd. per day as would the same plant for 1000 cu. yd. a pump at 100,000 gal. per day or 1,000,000 gal. The argument needs no further illustration. The question in any case is the extent to which labor may be released or transferred to other work whenever work must be prosecuted at a reduced rate. Thus it will be seen that in connection with nearly every operation there is an irreducible minimum expense no matter to what point the progress or output is reduced. Even in case of an interruption of such a nature and duration that all labor is laid off and operation entirely suspended for a time, there is still an expense for reconstructing the organization and bringing it to a state of efficiency on resumption of work, to say nothing of expense for protection of plant, watchman, insurance, interest, etc. Certain items of expense that are practically constant through both operation and shut-down are clearly to be classed as general expense, but it should be recognized that portions of so-called operating expenses partake of the same nature. The proportion in any case depends upon the plant, organization, nature of the operation, etc.
Whenever it becomes necessary to suspend work entirely the problem of unit cost is only to be met by a reduction of general expense, by discharging employees. The extent to which it is advisable to go in that direction is a matter of the known or estimated duration of the shut-down, probable dispersion of the force and the expense of reconstructing the organization when work is resumed. Whenever it is permissible or necessary to work, no matter at what rate of progress, the mere operation of plant for even the lowest rate entails at once a proportion (which may be considerable) of the total normal operating force. In such a case a satisfactory unit cost can only be attained, not by reducing the dividend, but by increasing the divisor; not in cheese paring or petty shaving of salaries but by boosting the output. To bring the force necessary for operation at half rate up to that necessary for progress at full rate is very largely a matter of adding to the number of laborers. At half rate many of the men (and those the very ones hardest to replace) are not working up to their capacity. While they thus have more or less opportunity for introspection it is unwise to furnish them with a grievance by cutting their pay.