PERMISSIBLE GRADES. Table 50 shows the steepest grades of brick pavement in actual use in 1900 in the cities named.
"The fact that such steep grades are in use, may not be taken as a reason for imitation, but may furnish conclusive reasons for avoidance. The most useful information on the subject can be obtained from teamsters and horsemen of these cities. If it is generally agreed that certain pavements are shunned by team sters because their horses slip and fall when going down a certain street with a load, it will evidently be unwise to repeat the con struction of the same kind of pavement with an equal slope in a similar climate. An examination of these pavements may furnish to the observer conclusive reasons for or against copying them, or may suggest changes in detail which would give better results. In investigating these steep grades, it should be borne in mind that the selection of the pavement for a given street may have been made directly or indirectly by the property owners, who have not necessarily chosen the pavement best suited to attract traffic. but who, preferring a quiet street, sometimes select a pavement which traffic will shun." * general statement of cost will be only approximately true for any particular case.
The grading is usually done by the cubic yard; and the cost varies with the character of the soil, the depth to be removed, the length of haul, etc. The cost of grading ranges from 15 to 50 cents per cubic yard; but in easy soil and moderate cuts, it gener ally varies from 20 to 30 cents. It usually costs 2§ to 3 cents a square yard to dress off the subgrade after it has been graded with drag or wheel scrapers, and to throw the material into wagons.
The cost of rolling the subgrade will depend upon whether it is rolled longitudinally only or both longitudinally and trans versely. With a horse roller the cost of labor in rolling the street longitudinally will probably not be more than 0.1 to 0.15 cent per square yard; but the cost on account of interest on the value of the roller will depend upon the amount of work done per year, and may be from to 1 cent per square yard. With a steam roller the cost of rolling, both transversely and longitudinally, will be about 0.5 cent a square yard. exclusive of interest, storage, and
depreciation of the roller.
The cost of the concrete will vary with the price of cement, the proximity of broken stone or gravel, the character of the concrete, etc. Ordinarily the materials for a 6-inch course will cost about 40 cents per square yard (§ 559), and the labor 6 to 8 cents per square yard (§ 560).
The price of brick varies greatly with the locality, particularly with the freight rate. The price of bricks or blocks is usually quoted by the thousand without stating the size or number re quired to lay a square yard. For convenience in making estimates and comparisons, Tables 51 and 52 • are given, to show the num ber required per square yard. The first table gives the quantities for the foundation course, and the second for the top course. In Table 52, the upper number in each entry is for i-inch joints, which is perhaps a little close for re-pressed blocks; and the lower number is for 1-inch joints, which is probably a little too open for a block not re-pressed. The price of bricks per thou sand at the kiln varies from $7.00 to $15.00, but usually from $8.00 to $10.00; and assuming the size to be 2-1" X 4" X 8k", of which 54 not re-pressed are required to lay a square yard of pavement, the cost will usually vary from 43 to 54 cents a square yard ex clusive of freight. The price of re-pressed blocks at the kiln varies from $12.00 to $14.00 a thousand; and assuming the size to be 3" X 4" X 9" of which 46 are required to lay a square yard (see Table 52), the cost of the blocks exclusive of freight will usually vary from 55 to 65 cents a square yard. In estimating the freight, it may be helpful to know that a brick 2" X 4" X 8" will weigh about 5 pounds, and one 2k" X 4" X 8k" about 7 pounds, and a block 3" X 4" X 9" about. 9 pounds. In estimating freight, the fact should not be overlooked that for one reason or another a con siderable number of bricks are rejected. With careful grading at the kiln the broken and rejected brick is likely to be 2 to 4 per cent.