Pick-up Machines
To improve on machine sweeping various types of motor pick-up machines have been invented. Most of them have proved of no value. Some, however, are being used by cities with good results on dry, smooth pavement in good repair. Most experts question whether vacuum cleaning will ever be able to remove effectively mud or wet dust. Some experts, however, believe that these pick-up machines will solve the problem of cleaning macadam pavements, as it is the only method that can be employed without serious results. These machines will travel at a rate of four miles an hour, which exceeds the speed attained by any horsepower sweeper.
The experience of Oakland, Cal., with this method of cleaning is interesting. Adjacent to the congested district a suction sweeper had been used for several years. The district had been swept from three to six times a week, by contract, to the satisfaction of the city officials. The department reports that the cost was rather high in comparison with that for rotary sweeping, but that the results were more satisfactory. It cost the city 35¢. per 1,000 square yards to clean with the suction sweeper and 26¢. per 1,000 square yards with the rotary brooms. It had been generally assumed that the patrol system was the most expensive until the Street Commissioner readjusted the routes according to area and traffic. He then found that hand sweeping could be done on streets not swept by rotary brooms at the same cost or not to exceed a ten per cent. increase. He found also that it could be done for much less than cleaning by suction machines. The city has, therefore, entirely superseded this method of cleaning at an estimated annual saving of $3,000 and with much better results.
Pomona, California, found that moisture upon the surfaceof a pavement or in any form of refuse cannot be lifted by a suction sweeper. Instead it is in effect smeared over the surface of the street. In all cases where the street is dry and the surface of the pavement is reasonably dry the city has found the machine very positive in its operation.
Los Angeles, California, is thoroughly testing the vacuum method of street cleaning following a report by the Efficiency Commission, which has estimated a saving of $65,071 a year if the streets are swept with vacuum cleaners instead of flushed. The report says that supplementary observations and calculations show that the cost of flushing under present conditions is 24.06¢. per 1,000 square yards, and the cost of vacuum cleaning 10.96 cents per 1,000 square yards. These figures include the cost of supervision, maintenance of equipment, workman’s compensation, gutter cleaning and water at cost of production. The cost of operating one of these machines is given by the Milwaukee Bureau of Municipal Research, as follows:
From personal observation it was calculated this machine can operate at a speed of four miles per hour and perform work at about 75 per cent. efficiency, or at a cost of 21.4¢. per 1,000 square yards.
The assessment per front foot based on a street 30 feet wide and cleaned 50 times a season would be 1.77 cents.
Raymond W. Parlin, Deputy Commissioner Street Cleaning, New York City, says: “So definite are the needs of the cities for results better than those produced by sweeping that it may be safely prophesied that sweeping in the future will cease to be a primary method of cleaning a modern city and will become an auxiliary to other more efficient methods or used where only rough cleaning is desired.”
All authorities agree that whatever method for primary cleaning is adopted, it is important that the street surface be frequently washed by the use of hose, horse drawn flushers, flushing cars, or power squeegees. Reports from cities show that flushing is replacing machine sweeping and that the automobile flusher is becoming popular. The Chief of the Atlanta Sanitary Department favors doing away with sweeping machine and cleaning the streets entirely with flushing machines. He says that sweeping machines are out of date and that flushers are the ideal machines.
The squeegee is a vehicle having a tank and a revolving rubber roller, which washes the pavement as the vehicle moves along the street and the water from the tank is sprinkled in front of the roller. Hose flushing is used in cities having graded streets and sufficient water supply. Street flushers have pressure tanks which depend for their pressure either upon the pressure from the water mains or upon the pressure obtained from a pump operated by a gasoline engine. The latter plan gives the better results.
Whinery is of the opinion that on well paved streets the most efficient and satisfactory method so far devised with the apparatus now available is hand cleaning by the patrol system by day, followed with hose or flushing wagons or scrubbing squeegees during the night. While this is somewhat more expensive than plain machine sweeping he thinks that no other method yet devised will produce equally clean streets at a lower cost.
Gustave H. Hanna says: “The use of flushers has proven not only the cheapest but the most satisfactory method of street cleaning that our experience in Cleveland has been able to develop. Statistics of the department show an average cost of 15.3 cents per square of 10,000 square feet for flushing to which must be added practically 9 cents for pick-up work, a total of some 24 cents per square as against 42 cents for work with White Wings. The White Wings are too convenient and necessary an adjunct to be wholly displaced under any consideration. Down town streets must be swept continually during the day and the hand sweeper with his small cart can also work to advantage in gutters of residential streets collecting dirt that has either been flushed or blown to the curb; but so far as our experience goes, the lessening of cleaning cost by cheaper methods means simply the extension of the use of flushers at every practical point.
“There is an argument of sanitation in favor of flushing. Hand sweeping causes a certain amount of dust and mechanical sweeping usually causes still more. I am opposed to the use of simple sprinkling as a means of laying dust. Ammonia and other products leach out of damp manure and form a scum on the surface that is nearly impossible to remove, and makes pavement slippery and foul smelling.
“Water should also be applied with force enough to carry the refuse to gutter where it should be properly collected with broom and shovel and removed. In Philadelphia flushing machines are used only on poorly paved streets and block pavement. High pressure flushing machines are usually operated similarly.”
Very reports that objection is made to flushing because materials are washed into sewers. The same objection, he says, might be made to hand sweeping, as many sweepers are like housemaids and sweep the dust into the catchbasins to make work easy. The material need not reach the sewers if the operator knows his business. Many fear that the action of water when used in flushing will wear away the pavement surface or the joint materials. His answer is that it should, if such a class of pavement or of jointing is allowed to be laid, to expose the paving contractor.
The Chicago Civil Service Commission says that personal inquiry and analysis of reports from cities using flushing machines seem to indicate that the use of flushing machines on rough and smooth pavement and the use of squeegees on smoother permanent pavements have given more effective cleaning than the ordinary block or gang cleaning where it is practicable to make the substitution.
The Milwaukee Bureau of Municipal Research, in its investigation of street cleaning in that city, says the contention of some is that flushing is detrimental to pavement as it removes grout, but such has not been proven in Milwaukee. The one fact that remains uncontradicted is that they clean the streets of every particle of débris and leave the thoroughfares in a sanitary condition; a matter of most vital importance.
In Milwaukee night work is confined to two territories comprising the heavy traffic and commercial territories and each alternating night the streets are flushed. This requires the use of four machines and they operate in a staggered double formation, cleaning the entire area without a return movement. When intersecting streets are encountered, the two rear machines perform the work and then return to the original function. A great deal more territory is thus covered than if machines were paired and each allotted a given area. Day work is performed in like manner except that the remaining four machines are assigned to outlying districts and confined thereto. The following is the cost of operating machine flushers as computed by the Bureau:
In recommending the flushing process the Milwaukee Bureau says that sprinkling will be greatly reduced, the slippery surface of thoroughfares due to this valueless method will no longer exist, and that a cleaner and more sanitary condition will be the result.
The experience of Scranton, Pa., with flushers is that in going over the streets but once satisfactory results are not obtained. The director of public works says that this has also been found in other cities he has visited where flushers are used. He has concluded that the only practical and efficient way to clean streets is by the use of automobile flushers, one to about one and a half minutes ahead of the other, the first flusher dampening the horse droppings and other material that may stick to the pavement, thus loosening them, and the second flusher sweeping them into the gutter.
Birmingham, Alabama, reports that its experience has been that a great saving and better results are obtained by substituting street flushers for sprinklers and brooms.
Some cities are having success with street railway flushers, among them Cleveland, Scranton, Columbus and New Bedford, Mass. Cleveland furnishes and maintains the flusher cars, pays the cost of operating them, including the wages of employees and the cost of power, but contributes nothing toward fixed charges or for track maintenance or renewal.
Commissioner John T. Fetherston, of New York City, reports that the Mack truck flushing machines which thecity put into use during the summer of 1917 are capable, according to preliminary investigation, of cleaning from 100,000 to 120,000 square yards of street per machine per eight hour shift, and that they will do the work with the use of approximately 400 gallons of water per thousand square yards.
There is a difference of opinion as to the efficiency of flushing by hose. In Philadelphia all alleys and streets whose width between curbs is too narrow to permit the use of street brooms are cleaned once each week with hose. When additional cleaning is necessary it is done with hand brooms.
Very says that hose flushing is ineffective and uneconomical, and that water does not reach the pavement in such manner as to give full effect and usually is doing no work at all.
One city report makes this comment: “Four or five sweepers hold a hose and play it in some sections as though the object were to wash away the asphalt block pavement and car tracks. Target shooting, with a stream of water, so-called flushing, will never supplant wetting and scrubbing.”
Very also claims that water to be effective must reach the pavement surface in a chisel shape and at a proper angle to remove and carry off the filth. He says that no man is properly constructed to hold the hose at a proper angle with the pavement to obtain the best results for any length of time. Commissioner Fetherston says New York’s experience shows that a hose gang consisting of two men is able to clean well from 23,000 to 25,000 square yards of the dirtiest Belgian block pavement in eight hours, and will clean upward of 30,000 square yards of smooth pavement of modern granite block in the same time, using 2-inch hose, which is that city’s standard size for use with its newhose reels. The amount of water required to clean 1,000 square yards is approximately 1,000 gallons.
The squeegee method is used on smooth pavements. Batteries of two and three squeegees are usually preceded by sprinklers, which use as much water as possible without flooding the pavement, while the squeegees use just enough water to create a wash. The idea of sprinkling the pavement is to soften the surface and enable the squeegee to cleanse the street of slime as well as coarser material. Squeegees are followed by men who sweep up windrows of dirt into piles and a sufficient number of carts follow to remove the dirt. In New York where no sprinkling cart is used they average 50,000 square yards per machine per day with the use of 200 gallons of water per one thousand square yards. In Washington with a sprinkling cart they get about 80,000 square yards per machine per day.
Parlin says that squeegeeing produces very effective results with a limited use of water on smooth pavements in good repair.
Very believes that squeegee machines have their value, and if the sprinkler cart is used in advance better results are obtained.
In Milwaukee machines are in constant operation on smooth surface pavements. In certain sections where streets are exceptionally wide, three machines are used in staggered formation and necessitate but one and one-half complete trips over a street to perfect cleaning. They are routed in such a manner that little idle travel is necessary and filling plugs are specified to prevent empty haul to any great extent. The same system is applied to territories where only two machines can be operated, except that four return trips are necessary to complete the work. In no wise are operators allowed to confine their work within a given block unless conditions prevent, but must continueuntil tanks are emptied, which usually occurs at end of second block. Two laborers are employed with these machines to keep gutters free from dirt and obstructing the water from flowing to the catch basins.
The average area cleaned in one year was 377,712 square yards at a cost of $96.35 per day or 25.5 cents per 1,000 square yards. Of the total yardage of pavement in the city 1,105,324 square yards are free from car tracks and subject to squeegee process. Some are squeegeed twice a week while others are cleaned but once and each have the additional service of White Wings and sprinkler.
The Milwaukee Bureau of Municipal Research gives the cost of squeegeeing as follows:
Manufacturers have placed on the market a modern motor driven squeegee said to be efficient and economical to a city with large area of smooth pavement. The capacity of this tank is increased to 750 gallons (an increase of 200 gallons over horse-drawn machine), which will permit a large area to be cleaned uninterrupted by constant filling, and reduce the lost time at hydrants. There are two sets of sprays, one directly in front of machine and one directly in front of squeegee. Back of the first spray or sprinkler head is a set of two brushes to loosen any hardened matter that might not be subjected to the squeegee process. By using this machine, the employment of laborers to continuethe flow of water to catch basins is unnecessary, as the discharge of water is sufficient to remove any slight particles that are removed by the horse drawn equipment. At the end of the season, the machine can be dismantled and a box attached to make it available for other purposes. The cost of operating this style is estimated by the Milwaukee Bureau to be as follows:
This cost data shows motor driven squeegees will perform twice the amount of work as horse drawn at a reduced unit cost. The difference in operating cost of two types would be:
Whinery says that while it is true that flushing methods, if thoroughly used, do carry the removed dust into the sewers or drains, which is regarded by many objectionable and to clog the pipes, this might happen where the whole of the street dirt, coarse and fine, is thus carried together into the sewers. He does not know of any instances where actual trouble has resulted. The practise of cleaning the streets wholly by squeegeeing or flushing is not, however, to be recommended, he believes, if for no other reason thanthat it would be impracticable to do the work several times each day and thus prevent the formation and flying of dust. The danger of clogging the sewers by flushing dust only into them is, he thinks, very remote, as the quantity of the dust remaining after proper coarse cleaning is small. Careful determination by the New York Commission on Street Cleaning and Waste Disposal showed that on smooth pavements cleaned by the patrol system the accumulation of dust in 48 hours after the street has been washed either by hard rains or by flushing, does not exceed five per cent. or six per cent. of the total daily quantity of street dirt, though on rough stone block pavement it may be much larger. This quantity is so small that its disposal through the sewers could hardly cause serious trouble. In fact, the large volume of water used tends rather to flush and clean out the sewers.
In a paper read before the American Society of Municipal Improvements, Mr. Parlin summarizes as follows the results of a study made by him to determine the economy of the various types of flushing equipment: “Hose flushing on small areas was the most economical method; that up to 40,000 square yards, the horse drawn equipment was next in economy; that from 40,000 square yards to 90,000 square yards the hose was about as economical as the automobile; that from 90,000 square yards to 120,000 square yards automobile was supreme, and for daily schedule areas of over 120,000 square yards the automobile and street car equipment give nearly the same economy.”
The street washing equipment of the future will probably be a combination affair. This has been used in Europe for several years. New York City is now developing combination equipment.
The ideal system of street cleaning would, therefore, be efficient patrol or hand cleaning through the day or during a longer period if the volume of travel in the evening requiresit, and thorough scrubbing with squeegees or washing with water under pressure by flushing machines or hose at night as often as may be necessary.
Although the automobile equipment has not been in use long, experience has shown that it is both efficient and economical, particularly in the larger cities.
In most cities the final disposal of sweepings and waste collected from the streets is a troublesome problem, and the cost is no small item in the expenses of the street cleaning department. The majority dispose of the sweepings on city dumps. A few cities are able to dispose of a part of the sweepings from paved streets to farmers and gardeners in the near vicinity on terms that repay at least a part of the cost that would otherwise have to be incurred, but the expense of handling and transporting the material to any considerable distance and its great bulk compared with its commercial value as a fertilizer place a limit on its disposal in this way. Nevertheless, it should be possible in the smaller cities at least to interest farmers and gardeners in the use of this material to a greater extent than is now common and to dispose thus of the sweepings at a price that would reduce the cost of disposal otherwise. The use of street refuse for filling low ground or reclaiming areas of shallow water and marshes has not been so seriously considered as it should be.
In some cities the street dirt is used as a fill between sidewalks and curb or in low alleys and vacant lots which are adjacent to the streets cleaned.
In other cities where the so-called “short haul” system is used, the street dirt is collected from stations at which the street sweepers deposit it, for filling purposes within the ward. The haul seldom exceeds three-quarters of a mile. One mile has been used as a standard for short hauls within wards.
Relative Cost of Street Cleaning
Most experts agree that little can be gained by comparing unit costs in different cities as local conditions and prices paid for labor, etc., vary so widely. Another reason is the lack of uniformity in standards and records maintained in the various cities. And still another reason is the varying standards of cleanliness. Very few cities in considering the sum to be appropriated first determine the standard of cleanliness to be attained. An investigation conducted by the United States Bureau of Census indicated that the unit cost of street cleaning in cities having less than 300,000 inhabitants is less than that in cities having over 300,000.
When the many different methods of record and cost keeping are considered as well as the difficulties encountered in obtaining accurate information as to conditions and methods used in the cleaning of streets, the reasons for these differences are apparent.
The Municipal Journalin January, 1915, printed a table which shows that the average number of cleanings per year in thirty-one of the largest cities was 156, varying from 37½ to 300. The cubic yards of sweepings per year per thousand square yards of street area averaged 20.5, varying from 5.7 to 48; the latter being in Boston and nearly four times that reported from Washington. The average amount of sweepings collected at each cleaning was 191 cubic yards per million square yards cleaned, varying from 32 to 440. The cost per thousand square yards of cleaning done averaged 35½ cents, varying from 14 cents to $1.53. The cost per cubic yard of sweepings averaged $2.70, varying from 79 cents to $8.75.
Table I (a)STREET CLEANING IN AMERICAN CITIESName of CityPopulationMiles of Streets Swept per YearArea in Square Yards Subject to CleaningHand SweepingMachine SweepingBy HandBy MachineTotalSmoothRoughMacadamTotalSmooth and RoughSmoothRoughMacadamTotalSmooth and RoughBuffalo, N. Y.461,3359,60034,000749,6007,964,500Beacon, N. Y.10,1651.526,400Binghamton, N. Y.53,000225.627.6114,829Cincinnati, Ohio402,17520,11210[1]254,951Cambridge, Mass.110,00015108.5350,0001,250,000Chicago, Ill.2,200,0004,674,396,308 S.Y.12,039,859 S.Y.19,841,4827,551,0536,605,237Camden, N. J.95,0002,249,314Columbus, Ohio220,000Cleveland, Ohio561,000Cortland, N. Y.13,0006Dunkirk, N. Y.17,87026Denver, Col.245,523102,501,230 S.Y.215,046,848 S.Y.Elmira, N. Y.40,09320,67241,000Fall River, Mass.124,791Grand Rapids, Mich.131,000Hudson, N. Y.13,00021.5Jamestown, N. Y.38,000130Kansas City, Mo.319,000462.65[2]Kingston, N. Y.27,0004Los Angeles, Cal.550,0003339,150,000Louisville, Ky.224,0008,331Lowell, Mass.106,294Lynn, Mass.96,00035Lackawanna, N. Y.17,5005.5Little Falls, N. Y.13,000674,0005,0003,000Milwaukee, Wis.450,00082252.51,600,170Middletown, N. Y.18,0004.288,235Mechanicville, N. Y.8,2085.New York City (Manhattan, Bronx & Brooklyn)4,551,8601,48728,429,78510,391,283New Orleans, La.400,000New Bedford, Mass.111,000Newark, N. J.370,000Norwich, N. Y.8,5006New Rochelle, N. Y.35,500584.67 Mi.47.1 Mi.6.3 Mi.25,000Niagara Falls, N. Y.45,000400Newburgh, N. Y.27,876Oakland, Cal.215,0004,1285,1607,333,000180,800187,851Oswego, N. Y.24,00090412,866778,374Ogdensburg, N. Y.14,3881–310Philadelphia, Pa.1,800,0004611,165750,1393,835,217Providence, R. I.248,000Rochester, N. Y.248,465258,171Rensselaer, N. Y.11,112Reading, Pa.110,000209,659 squaresRichmond, Va.160,00056,820,400208,031,600St. Louis, Mo.835,000405San Francisco, Cal.500,000460525,105,55165,228,812Salt Lake City, Utah120,0003054Springfield, Mass.102,971Seattle, Wash.238,0003,521,62412,324,340Scranton, Pa.130,000Troy, N. Y.76,00040.89727,11253,542Utica, N. Y.85,000½ sq. mi. daily.Washington, D. C.360,0001,513,5623,682,7661,584,524