3. Overhead Labor. Clerks, bookkeepers, messengers, office force, and General Manager are ordinarily included among the items of overhead charge, as well as salaries of general officers.
4. Overhead Materials. In this classification, there are included stationery, office furniture, supplies, etc. When the office furniture is disposed of upon the completion of the work, its value should be credited upon this item.
5. Overhead Incidentals. These may include various items, such as telephone, office rent, telegraph messages, express charges on incidentals not directly connected with plant, etc.
6. Preparatory Costs. These include the cost of getting ready to do the work, and, depending upon the nature of the job, may include any or all of the following items:
(a) Temporary roads;
(b) Temporary trestles;
(c) Clearing and grubbing;
(d) Snow removal and drainage;
(e) Traveling expenses to job;
(f) Preliminary estimates, calculations, and surveys;
(g) Freight and handling of materials to and from job;
(h) Freight on preliminary supplies;
(i) Handling of preliminary supplies;
(j) Licenses and premiums on bonds, etc.
(k) Legal expenses;
(l) Loss on initial operations;
(m) Right of way and cost of site;
(n) Sheds, storehouses, and other temporary buildings;
(o) Tools, less final value.
7. Supplies. These are chargeable F. O. B. the job, or at the railroad station nearest to the work. They include all supplies for carrying on the work, as distinct from material, including explosives, coal, oil, waste, etc., and may include a charge for water.
8. Interest and Depreciation on Plant. This item is variously estimated by different people, and may vary greatly. It is impossible to establish an absolute rule; but on the average contractor's plant, it may be stated that 1/10 of 1 per cent per working day is a very fair general average figure. The average steam shovel, for example, will work perhaps 200 days, under favorable weather conditions; and on this basis the interest and depreciation charge will be 20 per cent per year, and is not far from a fair figure. Some contractors allow 33 per cent per year on such material as road machinery, including crushers, steam rollers, etc. This is a little high, provided that a reasonable charge is made for repairs.
9. Repairs to Plant. How much money it takes to keep the equipment in proper condition for performing efficient work, is a question on which the limits of space prevent a detailed discussion. On such a machine as a standard-gauge steam locomotive in constant operation to the limit of its capacity, repairs may run as high as 20 per cent per year; and on a rock drill the repairs may be 50 per cent or more per year.
10. Rent, Stumpage, etc. The item of rent includes the rental of ground and the storage buildings, if any, outside of the office expenses. Stumpage is the cost of standing timber, the purchaser being privileged to leave the stump after cutting down the tree.
11. Materials of Construction. These are chargeable F. O. B. the job, or at the railroad station nearest to the work.