surfaces should be replaced every seven years; while asphalt is given a life of fourteen or fifteen; and wood, of ten years. The annual expenditure on the reconstruction of pavements is $64,369.00. Repaving is entirely done by contract. In the older streets the various pipes for water, gas and electricity, sewers, etc., are placed under the center of the roadway; in all the new streets they are beneath the sidewalks. The organization in control of streets resembles in form that of the French cities, consisting of engineers, inspectors, foremen and laborers, the last carrying on maintenance of stone streets. The cleaning of the streets and their lighting, the construction of sewers and other subsurface pipes, are carried on under other direction. As regards the various classes of pavement employed, the following items are of some interest: Average cost The porphyry blocks, similar to our trap, have an estimated average minimum life of 20 years; the granites, classified according to hardness, from 8 to 20 years. It is the conclusion of the authorities that the harder stones are the most economical and should be employed wherever grades will permit or on streets having a grade of less than 3 or 4%, their extreme hardness rendering the surface too slippery for use on the steeper grades, where the softer material is employed. It is interesting to note this point in connection with recent criticism which has been based on an assumed European practice the direct contrary of this. But there, as in the United States, the harder the material the better it will polish. The above estimated life of different classes of stone pavement represents merely the period during which the materials are assumed to be in a condition to remain in use in the principal streets. They are subsequently taken up and used in streets of secondary importance. For the latter streets an annual maintenance cost of $0.02 to $0.03 per square yard is involved and for the principal streets this is $0.10; or a general average throughout the stone paved streets of the city of from $0.04 to $0.04% c. Macadam This class of pavement, which is extensively employed, has a first cost of $0.83 a square yard, except where old stone blocks are broken up to furnish the material, when its cost is about $0.50 a square yard, while the reconstruction of macadam streets amounts to about $0.21 a square yard. The maintenance on this class of street runs from $0.04 to $0.05 per square yard per year. Asphalt Only a limited use of this class of pavement has been made on the streets under city maintenance. It has a first cost of $2.29 per square yard on a 4-inch concrete foundation, or relaid on existing foundation of $1.81, with an estimated life of about 15 years. The maximum maintenance cost on heaviest traffic streets is $0.16 a square yard; elsewhere, about $0.12% a square yards. This is regarded by the authorities as the most satisfactory type of pavement. Wood Both pine and Australian hard wood have been used since 1883, and their use has since been extended to variously important boulevards and avenues. The costs have been as follows: Soft wood, including foundation.. Per Square Yard $1.77 1.29 3.62 Boulevard Anspach, in front of the Bourse. Asphalt pavement, showing wear along tramway rails. On the Boulevard Anspach. Showing type of horse-drawn tram. car line on the pavements without rails. |