Table 46, page 441, gives data on the cost of repairs of asphalt pavements in Buffalo on residence and business streets with and without street-car tracks. Notice that the cost on business streets increases each successive year, while that for residence streets as a rule decreases after the sixth year. The first result is what would be expected; but no satisfactory explanation has been found for the anomaly of the second result. Notice also that the cost on residence streets is more with street-car tracks than without them, a condition which is contrary to ordinary experience. Both of the above anomalous results are doubtless due to poor work or to excess ive travel on one or more of the streets.
Table 47, page 442, shows the cost of maintenance of the asphalt pavements in Washington, D. C. These results are com piled from Table D, Asphalt Pavements on 6-inch Hydraulic Base, in the Report of the Operations of the Engineering Department of the District of Columbia for the year ending June 30, 1900. The original table is arranged geographically by streets and gives the cost of repairs for each contract for each year after the expiration of the 5-year guarantee period. The results in Table 47 are the means of the annual cost of repairs for the several contracts, and take no account of the different areas covered by the different con tracts; but the resulting error is not material. The most con spicuous feature of the table is that the pavements laid in 1878 cost much more for maintenance than those laid later, after the best method of doing the work was better understood.
Table 47 suggests comparisons with Table 45; but it is impos sible to draw any reliable conclusions, since nothing is known con cerning the relative amount of traffic per unit of width, and also since nothing is known about the relative excellence of the state of repairs in the two cities. In each case there is a considerable variation in the results from year to year, depending upon the number of streets that were re-surfaced that particular year.
In New York city, the average difference in contract price for a 15-year and for a 5-year maintenance for the three years pre ceding 1894 was $0.608, or 6.08 cents per square yard per annum, and for the three years following 1894 was 5.82 cents per square yard per annum. The area of pavements included was quite large, and hence the result is fairly representative.t In Berlin, Germany, the contract price for the mainte nance of the great majority of the asphalt pavements is 0.75 marks per square meter (about 15 cents per square yard), provided the total amount of repairs in one year is not more than 5,000 square meters (6,000 sq. yd.); if the total repairs amount to more than 5,000 square meters in a year, the price is 0.50 marks a square meter (about 10 cents per square yard).
It is often stated the cost of maintaining asphalt pave-. ments in Europe is from 10 to 25 cents per square yard per annum, an amount which is considerably higher than the average for America; but all such data are indefinite and unreliable, since noth ing is stated concerning the traffic and the state of maintenance. As a rule, the streets of Europe are narrower and the traffic per foot of width is heavier than in America; and therefore it is prob able that the cost of maintenance in Europe is higher than in this country.
In Washington, D. C., the cost of small and irregular patches is based upon the volume of binder and of mixture for the wearing coat used in making the repairs. The prices in the contract for repairs for the three years beginning July 1, 1900, are as follows:* No price is stated for painting the gutters, since the standard for new work requires brick gutters 2 feet wide, and the repairs to old asphalt gutters is made the same as in the remainder of the road way. The placing of stone toothing along street-car tracks is done by the railroad company."