ASPHALT REPAIR FOR SMALL MUNICIPALITIES. By W. H. TAYLOR, JR., City Engineer, Norfolk, Va. Just as certainly as pavements of asphaltic composition are laid, the subject of repairs soon becomes a real and not an imaginary event. In growing communities repairs caused by street openings for various underground services, are often necessary in advance of repairs from deterioration, however carefully such services are provided for in advance of laying the pavement. The mystery so long surrounding the construction of asphalt pavements having been dissipated and the simplicity of repairs. demonstrated, it is in my opinion the part of wisdom for municipalities, especially small ones, to construct asphalt plants in proportion to their repair needs, thereby establishing independence of the contracting world in performing ordinary maintenance work. The amount of repair work, in municipalities with small asphalt yardage, beginning with the first few holes of trifling dimensions, does not increase rapidly enough to justify costly outlays for repair equipment, during a period extending over years. The paving contractor cannot be interested in repair work until the amount assumes profitable proportions. The subject in its "infancy" and until it reaches its "teens" undoubtedly can be handled with an inexpensive apparatus susceptible of easy manipulation and of producing new surface material or renovating old asphaltic mixtures. With simplified equipment, the "personal equation" or skill of the plant foreman including familiarity with the products handled increases in importance and demands careful consideration. Recognizing that each municipality has its own peculiar problem or unique situation to deal with, a general law for asphalt repair work can hardly be framed. The work and necessity of rectifying a few small patches, one extreme, differs materially from the restoration or reconstruction of an entire street surface, the other extreme. The former problem or question involving "Repairs and Repair Plant for Small Municipalities" the subject of this paper, is one upon which much time and money can yet be profitably spent. Undecided after having investigated many plants manufactured for the purpose I am still investigating the subject with a plant homemade and with apologies intend giving an answer to the question at issue by briefly describing our efforts and the accompanying results. The city of Norfolk, Va., situated near the entrance of Chesapeake Bay, in Latitude 36 degrees 51 minutes N., Longitude 76 degrees 17 minutes W., has 80 miles of paved street, 43.7 miles of which are of sheet asphalt or bitulithic construction, totaling 668,320 square yards. The streets of the city are on an average elevated 8 to 10 feet above mean sea level. Drainage and sub-soil conditions are unfavorable, occasioning unusual maintenance outlays. As the scope of this paper will not permit of a discussion of our best and poorest efforts in constructing sheet asphalt, of contributory causes and errors revealed by time, leading to some early failures and numerous repairs, permit me to state that we have endeavored, when permitted, to follow closely expert advice and standard specifications, and have constructed streets that have endured reasonably heavy traffic for fifteen years without repairs, and we have a few streets, repairs to which have aggregated to date over 50 per cent. of the original area. An analysis and subdivision of our streets into classes, according to various specifications, reveals the following relative durability and percentage of repairs. The age of the streets in the various classes being about the same and traffic conditions not dissimilar: Class 1-Asphalt on concrete base-Streets without car tracksYardage 189,200. Total repairs to date 2.6%. Class 2-Asphalt on concrete base-Streets with car tracksYardage 147,000-Total repairs to date 29%. Class 3-Asphalt laid on old cobble stone base-Streets without car tracks-Yardage 14,236-Total repairs to date 39%. Class 4 Sheet asphalt laid without binder, on concrete baseStreets without car tracks-Yardage 21,044-Total repairs to date 25%. The question of repairs and of satisfactory equipment for making repairs became one of considerable moment and importance to the city of Norfolk within a very short time following the expiration of the guarantee period of the first large construction contract. Briefly stated, the methods pursued which have resulted in our present system, departing from the ordinary only in that we have used extensively for small repair work old surface mixture, vast quantities of which I have seen discarded and used for filling, have been as follows: In 1908 the Barber Asphalt Paving Company having completed a contract in Norfolk involving both new work and extensive repairs, just before dismantling the plant furnished the city 266 tons of sheet asphalt surface mixture. This was stored in layers separated by boards and cut in cubes before cooling. With painstaking care and unlimited patience, the Department of Public Works of Norfolk made its first asphalt repairs by reheating the previously prepared mixture in a fire wagon built for the purpose. However for very limited work only would I advocate or advise such a procedure. With the above exception, from 1906 to 1912 repairs in Norfolk were made by contract, the price varying from $2.00 to $1.40 per square yard exclusive of base. Our repairs at the present time average about 1,000 square yards per month, to be exact, 23,500 square yards the past 2 years, and are made by city pavers working usually one week each month. This rate maintained annually amounts to 24% of the yardage of all pavements in the city five years old and over. Whether more or less in amount than it has been Norfolk's misfortune to cope with, everywhere repairs are inevitable and in view of the extravagant and exacting demands of the traveling public, I repeat, preparations for repairs should, in my opinion, soon follow original construction. Frequently, in years past, while waiting for a contractor's plant to become available, we have had small holes spread from curb to curb, increasing in size with unbelieving rapidity, occasioning just complaints which we were powerless to correct. Independence of the paving contractor for repairs, established by constructing a very small plant, has enabled us to keep Norfolk's streets in far more satisfactory condition and to reduce the cost of such work from the previous low price of $1.40 per square yard, average of $1.75 per square yard, to 60 cents per square yard. We have made many thousands of yards of repairs at 50 cents per square yard using old material. The average cost above stated of 60 cents for the past two fiscal years, embracing the use of both old and new materials, includes all regular repair charges and 33% each year of the original total plant cost-itemized as follows: I submit herewith a free-hand sketch or diagram of the equipment with which we have accomplished the above mentioned results. It was created or constructed of much discarded material and a few minor purchases, the result of authorized experiments, looking to the use of a large amount of sheet asphalt pavement taken up and removed for the construction of a street railway, and collected on a vacant lot. From an abandoned crematory steel smoke stack 4 feet in diameter) two ten-foot sections were cut. Of one section a drum or cylinder was made, and a shaft was run thru the center and supported on journal boxes, enabling the drum to be readily revolved. The usual spider and loading chute were constructed at one end and a discharge opening next to the outside of the circle was cut in the other end. The drum was mounted above a brick fire-box or furnace, in length about 18 inches shorter than the drum. Above the brick work a portion of the stack, section No. 2, was used to enclose the furnace over and around the drum. A 5-h. p. motor furnished power thru reduction gears and chain drive, to revolve the drum at the rate of 12 revolutions per minute. The loading chute terminates in an elevated platform from which an incline leads to the ground. The inside of the drum has fixed to its sides spiral vanes so arranged that they propel the material as the drum revolves towards the unloading end. It has several proportionately larger movable vanes or doors, so arranged that the material is propelled in a direction opposite to that set up by the fixed vanes, or when willed, in the same direction. When set to work against the fixed vanes, the movable doors, one of which terminates at the unloading opening, prevent the material from coming out of the drum, and keep it well and evenly distributed thruout its length. When otherwise set the material is rapidly propelled towards Intersection Main and Bank Streets--Business District. Intersection Boush and Bute Streets-Semi-business District. |