STREET CLEANINGSYSTEMS AND APPARATUS USED IN AMERICAN CITIES—METHODS OF REDUCING LITTER—COST DATA.
In establishing or rearranging its street cleaning system, every city must consider the problem from three angles: (1) Cheapest method of cleaning pavement; (2) Method of reducing litter; (3) Paving policy with a view to saving cost of cleaning.
The proper solution of each one of these problems will materially reduce the cost.
In outlining a program for a street cleaning department the following elements must be known and carefully considered:
Mr. S. Whinery, Consulting Engineer, says that in most cities the data afforded by local past experience and results, furnish the best basis for future projects and programs. Unfortunately few cities have records of these. The head of the department usually relies upon his own memory or that of his predecessor. While the methods followed and results obtained in other cities may and should be studied, it must be borne in mind that it is not safe to base conclusions upon such data without a full knowledge and carefulconsideration of all facts and conditions affecting them. This is particularly true of reported cost data, for in addition to differing physical conditions, it is unfortunately true that the present methods of accounting in many street cleaning departments make it next to impossible to ascertain the actual or relative unit cost of the various details of the work, and intelligently to compare results in one city with those in another. The experience of the New York State Bureau of Municipal Information in seeking data from the fifty largest American and all New York State cities provides ample proof of this condition. Fifty were able to give some data, but of these only a few had any accurate and detailed cost statistics.
The relative amount of dirt from the different sources of dust depends on the character of construction and condition of street surface, amount and character of traffic, character of neighborhood and people in the neighborhood, and street railway tracks.
Street dirt is divided into two general classes: (a) Natural, and therefore unavoidable, and (b) that due to carelessness and therefore avoidable. In the first class are dust from the air, and dirt coming from the wear of pavements, vehicles, tires and horses’ shoes; excrement of animals, dirt and sand which work up through the joints of pavements, laid on earth or sand foundations and having sand or gravel joints; dirt brought in from adjacent unpaved or macadam streets, and leaves from shade trees. In the second class are soot, refuse swept from sidewalks, thrown from buildings and discarded by pedestrians, dirt dropped from overloaded vehicles and débris from construction operations.
The real duty of the street cleaning department is the removal of the first class, but in doing so it is compelled also to sweep up and cart away the material in the second class. In order to reduce its operations as much as possible, it must, therefore, in cooperation with the police and health authorities do everything it can to prevent the accumulationof the avoidable material by enforcing ordinances and through the cooperation of the public in general.
It is generally agreed that street cleaning by municipal employees is more satisfactory and economical than by contract. Even the officials of those few cities which still have the contract system favor municipal operation. Philadelphia is the only one of the twenty-five largest cities in the country which does the work by contract. The chief of the highway department has recommended a change, giving the following reasons: “Street cleaning work involves so much detail for which there are no definite units to specify and bid for, and it is of such a character that the overhead charges for proper inspection are so disproportionate to the cost of the work, that unquestionably it would be much more effectively and economically carried on directly by the municipal forces instead of by contract.”
Washington’s experience is illuminating. Notwithstanding changes in method as work progressed and considerable expense attached to the purchase of new equipment the street cleaning department was able to show at the end of the year under the municipal system that the average costs were less than contract prices. At the end of the second year for the expenditure of the same amount of money over 25 per cent. more work was accomplished than during the last year of the contract system and the general opinion was that the streets were in better condition than they had ever been before.
Street cleaning departments of many progressive cities within the last few years have given particular attention to the preventive side of street cleaning work,i. e., reducing the amount of avoidable dirt on street pavements. Variousmethods have been adopted to secure results. Local civic pride and the cooperation of the public have been stimulated by means of educational campaigns. One result has been the more general use of waste paper and refuse street cans. Cleveland tried to organize volunteer corps among the school children to use their influence against the useless littering of streets. Departments have also established a closer relationship with the health and police authorities for the enforcement of street cleaning regulations, such as those prohibiting the sweeping of litter from stores and houses onto paved streets. The success of preventive work depends upon the amount of cooperation the street cleaners can get from these sources.
In Chicago an analysis was made of the character and percentage of waste thrown about by pedestrians in the streets and by business houses in densely populated sections of the city. It was found that a great portion of the street dirt collected by street cleaners consisted of waste paper and other light litter. The Chicago Civil Service Commission in a special report says: “It would appear that with the cooperation of merchants a considerable portion of such litter could be kept off the streets and if street cleaners would patrol the street for loose paper and deposit the same in the street dirt boxes provided at different points along such streets, a great portion of the cleaning work would be saved and the streets would generally appear cleaner. The litter of streets in tenement and manufacturing districts is a matter which can be greatly minimized by proper distribution of work and cooperation of the street cleaning forces and residents. The quantity of street dirt collected from the pavements in market places illustrates an instance where pavements become unavoidably littered.”
Gustave H. Hanna, when head of the Cleveland Street Cleaning Department, expressed the belief that nothing encourages carefulness on the part of the public so much as efficient and careful cleaning. He argued that a man doesnot hesitate to throw paper or rubbish into a foul street, but thinks twice if the street is clean. If there is a waste box at hand with a printed suggestion on the outside, Mr. Hanna thinks he is apt to use the box.
The greatest source of expense comes from those who use the street as a place of business, such as resorts of professional hucksters. Mr. Hanna and others think it would be a small return for the permission of doing business in these streets to require the hucksters to keep the surroundings clean at their own expense under pain of arrest or forfeiture of privilege.
In an effort to get the cooperation of the general public, Philadelphia placed waste paper receptacles in prominent locations throughout the city, such as two in every block in the principal business sections, in front of school houses and entrances to business, elevated and subway stations, etc. Circulars were sent to each householder throughout the city containing information and instruction as to improving conditions by using uniform and suitable receptacles.
Bulletins and letters of information were distributed among business and civic associations. The officials learned that one of the most effective methods in reaching the householder is through the women’s organizations. A woman inspector was appointed to keep in touch with the activities of the women’s clubs and to secure their cooperation. This inspector during the year gave over two hundred lectures to various organizations and enlisted the cooperation of householders, women and children in connection with preventive street cleaning measures. To the housekeeper it was shown how vital is her part in an efficient collection of all waste. Children were impressed with their duties as citizens, and to them was given an opportunity to demonstrate their knowledge in the home, school and on the street. As a reward of such activity 5,000 buttons were distributed in six months. Twenty thousand folders forchildren and adults relating to the care of streets and the collection of waste were also put into circulation.
Former Street Cleaning Commissioner William H. Edwards, of New York, says that four kinds of cooperation are needed by street cleaning departments:
(1) “Cooperation with the force by showing a human interest in the work of the men. This can be done by establishing a pension fund so that when a man has served faithfully for twenty years and has reached the age of 60 or has become incapacitated after he has served ten years, or is injured in the performance of his duty at any time after service has begun so that he is disabled for future service, he can be retired on half pay. This instills in men a keen desire to do better work and permits the Commissioner to retire men who are no longer able to do good work. The danger of street sweepers in busy streets is apparent to any one. More than 2,500 accidents resulting in death or personal injury or damage to property occurred in one year in connection with the New York City Department’s activities. The percentage of killed in the street cleaning force was considerably higher than that in the police force.
(2) “Cooperation of women in the communities in New York. The Women’s Municipal League and other bodies have cooperated with the department. Every year they offer a medal to the sweeper, driver or foreman who does the best all around work.
(3) “Cooperation with citizens. Carelessness up to the present time has added to the work and expense and has been an obstacle to real cleanliness. It must be remembered that before the sweeper can begin that part of the work which is beyond prevention, he must remove the litter carelessly thrown on the street.
(4) “The formation of ordinances for the prevention of this carelessness. If the department has the effective cooperation of the police department and of the magistrates, in the enforcement of the ordinances, then and onlythen can this particular condition be reduced to a practical minimum. In an attempt to enforce ordinances forbidding the throwing of litter in the streets, New York City in 1915 caused the arrest of 5,400 persons for violating ordinances relating to street conditions of the scattering of refuse. In addition to these arrests in the last three months of the year more than 18,000 formal written warnings were issued for the violation of ordinances.”
The conditions and factors controlling the amount and frequency of cleaning of any pavement, are as follows:
A study made by the Chicago Civil Service Commission definitely established that the density of horse traffic, which is the total number of horses passing through a given street divided by the width of the street, is the principal factor which determines the number and frequency of cleanings one street should be given.
The Commission has also learned that there are at least thirty-eight distinct movements which a street cleaner makes in street cleaning work. Of these some have been found to be unproductive, resulting in loss of time and energy and less effective street cleaning. The most important of these, according to the Commission’s report, are as follows: Observation of time wheeling push carts into alleys or other dumping places, disclosing that practically one-fifth of time was consumed in this activity. The study disclosed that some sweepers are more efficient than others,due to the stroke of the broom which they make. The practise of hitting a broom on the pavement is not necessary on dry pavements and very seldom on wet pavements. Effective and practical street cleaning can be obtained by bringing the brush down forcibly at the beginning of each stroke, thus reducing the work at least 15 per cent. The time schedules disclosed that time lost by street cleaners in dodging horses and automobiles where traffic is dense is unappreciable and does not exceed 8 per cent. of the total time in the business district and not more than 2 per cent. of the total time in the outlying district. It is occasioned more through congestion of traffic than through density of traffic. In cleaning light traffic asphalt pavements it was disclosed that after the one morning thorough cleaning three-fourths of the area to be covered during the remainder of the day does not require thorough cleaning. The Commission believes that scoops equipped with rollers would be well adapted for use on light traffic pavements, and with them one man could patrol a much larger pavement area and still keep the pavement in good condition. Time studies of work performed by street laborers working in gangs showed that work done by groups and gangs was not as economical as the division of such work through individual arrangements. Considerable time is lost in conversation. When one man rests every man on the street does the same thing. While working in gangs the good sweeper does no more work than the poorest of the gang. Where it is desired to cover a large area of street with men working in groups rather than in gangs it would be better, the Commission thinks, for each man to have a definite uniform area to cover and to require the foreman to time each individual.
Mr. Edward D. Very, Sanitary Engineer, says that any attempt to estimate the amount of materials which accumulate on a city street must end in failure as the contributing elements vary in different localities in a city and indifferent cities, and where figures are given they do not really present any valuable data. Some general principles, however, have been determined. The Chicago Commission in its investigation declares that the quantity and volume of dirt attributed to horse drawn vehicle traffic is the most important source of street dirt. The loss of sand and coal and crushed stone, hay, manure and other loose material from poorly constructed vehicles or overloaded vehicles adds greatly to the quantity of street dirt to be removed. Important in a wet season is the dirt carried by moving vehicles through streets and alleys onto hard pavements, but the Commission says that the amount of dirt actually attributable to this source is considerably less than is usually believed. There is also considerable refuse in the form of leaves and grass which accumulates in the residential streets and along boulevards and parks, which has a tendency to lodge in catch basin inlets and stop the free flow of storm water. The quantity of leaves accumulating in the short leaf season on streets far exceeds that which naturally drops onto the surface of streets alone, because of the additional cleaning from lawns and parkway spaces.
Some reports express the belief that when a fixed standard is established of basing street cleaning schedules carefully on density of traffic, condition of pavement, character of frontage and kind of pavement, a definite relation will be found between the amount of street sweepings collected and the number of sweepers employed. In Chicago it has been found that different sweepers average daily collections of quantities varying from three-fourths of a cubic yard to three cubic yards. It has also been noted that street sweepings collected by regular block sweepers average about .0045 cubic feet per square yard. The weight of sweepings will, under ordinary conditions, approximate 36 pounds per cubic foot.
The paving and repair policy of a city is a very important factor in cleaning rates. Comparatively few citiesas yet give any thought when selecting a particular pavement as to the relative cost of keeping it clean. It is also a fact that in many cities repair work is neglected at the expense of cleaning.
A smooth, hard surface pavement will cost less to keep clean than one with a rough or uneven surface. A brick pavement, for instance, costs more to keep clean than sheet asphalt. For the same reason a street out of repair is more expensive to clean than one in good repair.
Officials agree that a paving policy should be carried out with a view to having a minimum number of unpaved approaches to existing pavements in order to prevent mud being tracked from the highway to pavement. There is need also of protecting narrow rural pavements from the overflow or tracking of mud that originates on adjacent portions of the same highway.
In a discussion of paving policies and their relation to street cleaning Mr. Hanna says: “The construction and maintenance of pavements that are easy to clean are important and effectual in saving the cost of street administration. Little weight is given to cleaning cost when paving questions are settled and an actual expense of $500 a mile in repairing residence streets would be considered an appreciable item of maintenance, yet that figure for cleaning a mile of residence streets through a season is extremely low. A street cleaner looks upon two qualities in a pavement. It must be smooth and particles of litter must not stick to the surface. The question of smoothness opens up the whole matter of durability. Any material that deteriorates or roughens becomes more difficult each year to clean. Any neglect of needed repairs means a larger cleaning bill until the repairs have been completed. The twofold expense resulting from wear, the cost of repairs plus the increased cost of cleaning should enter into all calculation of expense. Additional calculation of cleaning expense must be made for all bituminous pavements on accountof the sticking of particles of litter to the surface. These surfaces are never quite so clean as non-adhesive materials and it costs from 25 per cent. upwards in additional cost to put them in a reasonably presentable condition on account of this quality. This difficulty is seen at its worst in a new creosoted wood block pavement, when the oil is gradually working out between the pores of the wood. The use of steel scrapers must often be employed as the flushing by water is not at all effective in removing the dirt from the surface.
“Substances most easily cleaned that enter into pavements are brick and stone. Neither originates any dirt, and both wash off readily. The only ground for discrimination between them is on the question of smoothness where brick has a slight advantage as a rule. In the use of these materials the choice of a filler is all important. A bituminous filler has all the disadvantages of a bituminous surface. Being softer than the brick or block it recedes, leaving a crevice that invites lodgment of dirt; with edges of brick or block unprotected it is sure to roughen, thus adding to the difficulties of cleaning. Such a street after a few years presents the appearance of cobble stones with the filler invisible or else melted and run to the gutter where it impedes work of follow-up gang.”
Mr. Hanna recommends only a cement grout filler. He says that West 14th Street in Cleveland has a grouted brick pavement ten years old and a traffic of two vehicles a minute. It is cleaned on an average of five times a week, being flushed by night and hand swept by day. The cost of cleaning is almost exactly 15 cents per 10,000 of square feet. This is the lowest figure the city has been able to reach on any type of pavement. Mr. Hanna says that the cost on the best asphalt would not be less than 20 cents and would rise to 30 cents if the surface became wavy or rough. Wood block costs approximately $1.00 a square to clean in its initial condition, and it would be at least two yearsbefore oil will have dried out sufficiently to admit its being cleaned for 30 cents a square. Tar filled brick pavement will cost not less than 30 cents a square, and if the filler disappears and the block roughens this cost will amount to 60 cents or more. In the case of a pavement 40 feet wide there are about 21 squares to a mile.
Thus Mr. Hanna points out that as between a material that can be cleaned for 15 cents and one that can be cleaned for 30 cents, there is a difference of $3.15 per mile for cleaning, a difference of $15.75 per week, or $630 per season of 40 weeks—$6,300 in ten years. In Mr. Hanna’s judgment cleaning costs can be greatly reduced by a policy of prompt repair. He believes in the continual patrol of all city streets by men whose duty it is to discover defects in pavement and prescribe repair.
The unit work must be established and the responsibility of each employee fixed in order to secure an economical administration of street cleaning. This principle is illustrated by the so-called “block system.” By this, each man is allotted to a definite area of pavement to clean, which varies in extent depending upon local conditions as to traffic, physical condition of pavement, location of street, proximity to public buildings, population, paving, alleys, street cars, right of way and frontage of streets.
It is the practise of up-to-date cities to prepare schedules showing the character of pavement, area of pavement, number of cleanings or patrols per week, and the standard of work required of each street cleaner. Changes in these schedules are necessary from time to time on account of climatic conditions, street repair and other necessities. The Chicago Civil Service Commission says that to obtain definite standards of schedules for cleaning streets and alleys and the need of repairing such streets, the routing of teamsand vehicles, collecting of city waste, the amount and character and physical condition of all pavements must be obtained.
Pavements are usually classified according to physical character for the purpose of determining the amount and character of cleaning as follows:
Improved—Permanent (a) Smooth pavements, including asphalt, creosote block and bitulithic. (b) Rough pavements, including brick, granite, cobble and rubble and other pavements which require that dirt be picked from interstices.
Improved—Not permanent. All macadam pavements and country roads.
Unimproved pavements. All streets that have not been paved.
The oiling of macadam within the past few years has had an excellent effect on this kind of pavement and has given it the solidity and usefulness almost approaching improved permanent pavements. On macadam surface streets, periodical removal of rough material with hoes, brooms and shovels from street surface and gutters and sprinkling in dry weather with water or oil is about the best that can be done. An analysis in Chicago of the standard of work which one man can perform on an oiled macadam street, indicates that the rate of cleaning one and three-quarters miles of oiled macadam of average width in an eight hour day can be reasonably expected of any man.
Much waste is caused by lack of system in laying out the work and improperly directing the street cleaning gangs and teams. The attached tables give the systems now being used in fifty American municipalities. A study of these will show that some very definite ideas have been developed by street cleaning officials in this country. For example,most cities prefer having patrolmen work singly instead of in gangs.
In making assignments attention should be given to the smallest details, such as correct reports from foremen as to the number of streets swept and loads carted away, and the correct number of sweepers in each street. In many cities three are sent through a street when two would do. Dirt wagons should not be started immediately behind sweeping gangs as it usually takes thirty minutes to an hour before a gang can sweep up enough dirt for a full load. Dirt teams should not start for at least one hour after the sweeper begins. Gangs should have allotted to them enough work to keep them busy until quitting time so that they do not have to kill time. Laxity in any part of the system eats up the department appropriation.
The spring cleaning system usually calls for the piling up and removal of the heavy dirt which is washed from the center of the street and which accumulates in the gutters during the winter season. The experience of cities with such work indicates that the assignment of one man to a definite length of street, or the assignment of a small gang of not exceeding three men, to definite lengths of streets is more effective and economical.
The Chicago Commission says that where a gang of three men is assigned to the work, team work is developed by the use of one man in removing the dirt from the roadway and one man each from the gutters. In the granite and brick pavements considerably more brooming is necessary on the roadway. Granite, brick and cedar block pavements require that the dirt be scraped from the center of the street to the gutter before piling in the gutters can be commenced. The center cleaning rates per man in Chicago are given as follows:
The single gutter rates in miles per day per man are given as follows:
Chicago has found that the unit cost of spring cleaning of macadam and cedar block streets of different physical condition is as follows:
Although many cities sprinkle their streets for dust laying only, it is agreed by all experts and the heads of most street cleaning departments that the use of sprinkling carts for this purpose is of no value,i. e.it is a temporary makeshift and the result is nil. Sprinkling alone does not clean pavements, but only converts temporarily the fine dust into mud, which is a nuisance. It is quite generallyagreed, too, that sprinkling is responsible for much repair work on pavements.
The number of times a street is sprinkled daily depends upon weather conditions, nature of pavement and location, and rarely exceeds four trips. Where flushing and squeegeeing are done sprinkling is eliminated entirely.
In Providence, Rhode Island, bituminous pavements are not sprinkled by water. They are kept clean by patrol system and reasonably free from dust. It is the belief of officials of that city that the use of water has an injurious effect on the pavement.
George D. Warren, of Boston, an expert on paving, says that street sprinkling as it is generally practised is worse than a useless expense. He points to the fact that there has been no sprinkling in Providence in seven years on all kinds of pavement, except that water bound pavement is occasionally sprinkled with oil or oil emulsion. If bituminous pavement surfaces are dry and clean the oil which drips from automobiles is quickly spread by auto tires to an extremely thin sheet, which not only preserves the pavement, but the slight amount of oil takes up the fine dust and materially helps to prevent the surface from even becoming dusty.
Mr. Warren believes that while some forms of pavement are doubtless more affected by water and mud than others, sprinkling injuriously affects all classes of pavement. Continuing he says: “I believe that repairs required to all classes of pavement are more generally the result of wetting down the dirt, leaving the surface in a more or less muddy condition than by traffic, or rather what would be traffic under dry cleaning conditions. A city or street in or on which sprinkling or other methods of continual wetting of pavement surface has not been practised is almost usually one where the pavements are the best of their kind. Washington has the enviable reputation of having the most durable pavement of all kinds. For many years the system of cleaningthere has been hand patrol without sprinkling, except a very light sprinkling, just enough to lay the dust, not to convert it into mud—immediately in advance of night sweeping.
“Fifth Avenue, New York, is always dry except during rains, and we find one of the most durable asphalt pavements in the world. The pavement is always clean and never dusty.
“Asphalt pavement on Alexander Street, Rochester, New York, laid in 1885, is still in existence and has a record for low cost of repairs, and has until quite recently been free from street sprinkling. It is now rapidly deteriorating.
“Rutger Street, in Utica, New York, laid in 1886, has been through a similar experience of no sprinkling. Michigan Boulevard in Chicago, from Jackson Boulevard to 10th Street, was paved partly with creosoted wood block and partly with asphalt. It was always in a dry condition and carried very heavy traffic for ten years and was in a good condition until about four years ago when it was removed on account of widening the street. The bituminous pavement on Michigan Boulevard is always clean and never cleaned or sprinkled other than by patrol cleaning, except as to narrow strips about four feet wide which are sprinkled and hand broomed at night to remove the slight dust which collects near the curb.”
The Bureau of Municipal Research of Milwaukee reports that in that city 298 miles of street are sprinkled at a cost of $60,310.05. Of this amount $55,104.77 is assessable.
The balance is the city’s portion for public property and street and alley sections which is charged to the general city fund. The city used 275,498,112 gallons of water, costing $28,416.65 including $8,800 for hydrant rental. The average rate of assessment per foot front is about .017¢. In some cities where water is unavailable outside of citylimits, or available only for a short time, oil has been used to meet the demands for dust prevention. What seems to be the best is some non-volatile oil that will quickly penetrate the wearing surface of the road incorporating itself with the fine particles so that it forms a dense, smooth, waterproof coating, or else renders the surface dressing so heavy that wind will not hold it in suspension in the air. In addition to this its non-volatile character gives it lasting qualities.
The Milwaukee Bureau of Municipal Research believes that “The service at its best is of no value as it does not clean but only allays dust on the street where in its wet condition it requires a further process of cleaning by the squeegee or flusher and White Wings. If the city had a sufficient amount of modern equipment to clean streets more frequently, the valueless method of sprinkling could be eliminated and an enormous expense saved.”
In some cities street railway companies are required to sprinkle between their tracks and for certain distances on either side of the track. The legal question has several times arisen, whether a Municipal corporation has authority to enact an ordinance to compel railway companies to sprinkle in this way and also whether the particular ordinance in question is reasonable, or so unreasonable as to be void. Generally speaking it has been decided that such an ordinance must be specific, not burdensome, and confined to the company’s tracks, though in one case in Massachusetts, under the statutory powers conferred upon municipal authority, an ordinance requiring sprinkling from curb to curb was sustained. Courts have held that an ordinance providing that “each and every Company or Corporation operating street car lines within the limits of the city of ——— shall water their tracks so as to effectually keep the dust on the same laid,” and provides a penalty for its violation, is neither indefinite nor wanting in uniformity.
The question of sprinkling streets before sweeping hasbeen discussed repeatedly. Following are the methods used in some cities:
New York.—Sprinkling before machines. No sprinkling before hand sweeping.
Chicago.—Sprinkling before sweeping. The Chicago Code of 1911 requires that street car companies shall keep well sprinkled with water in a manner satisfactory to the Commissioner of Public Works, all streets on which they maintain and operate their tracks. They are required to sprinkle such streets twice each day. By another section such street car companies shall clean such portions of streets as lie between the two outermost rails of such tracks and also every additional service as may be prescribed in any railway ordinance relating to or affecting any street.
Philadelphia.—The proposals and specifications for the cleaning of streets, roads, alleys, inlets and markets for 1915, contained the following provision: In addition to the cleaning by blockmen required under these specifications, all streets must be periodically cleaned by machines, the number of weekly cleanings being given in the classification of streets, the remaining machine work shall be done with machine brooms immediately preceded by sprinklers.
St. Louis.—Sprinkling before sweeping is very rarely done, except in the case of certain large sweeping machines used by the city.
Baltimore.—Sprinkles before sweeping.
Pittsburgh.—Principal thoroughfares including all streets in business district cleaned by machine sweepers. Water cart precedes sweeping machine. The cart must never be more than one block ahead of the sweeper.
Washington.—Superintendent of street cleaning gives his opinion that much more effective sweeping can be done without sprinkling and in hand patrol work where dirt is not allowed to collect in any considerable quantity is not necessary. In machine sweeping, however, he finds it necessary to sprinkle with a small amount of water. In cold weather sprinkling is omitted; but at such times many complaints are received on account of dust.
Minneapolis.—In general the orders of the street district commissioners are to sprinkle the streets before sweeping.
Four methods are used in American cities for street cleaning, hand sweeping, machine sweeping, flushing by machine and hose and squeegeeing.
All experts advocate the sweeping of streets by hand, commonly called the patrol system. The implements used in patrol cleaning are broom, pan scraper, squeegees, can carrier and cans. The broom is usually one which has a 4 × 18 inch block, filled with split bamboo, rattan, hickory, steel wire or black African bass. The block is usually fitted with a steel scraper. The pan scraper is constructed like a dust pan, turned up sides and back. It is about 36 inches wide by 15 inches deep. The squeegee is a board about 36 inches wide fitted with a rubber strip which extends below the lower edge of the board. Brooms, pan scrapers and squeegees have handles about 66 inches long. The cans are made to hold about three cubic feet of dirt and taper 19 inches in diameter at the top to 17 inches at the bottom. The can carrier has two large wheels and two small, and a platform upon which the can or cans rest.
A new carrier has been devised which carries two cans and is so balanced that the two cans are more easily manipulated than the one. Some cities are now substituting canvas bags for cans.
Whinery says that when street surfaces are of such character as to admit it, hand sweeping is the most effective method.
J. W. Paxton says that hand cleaning work is capable of better distribution than any other method, because more attention can be given to dirtier areas by increasing the number of men who only clean the portions of the street which are dirty and work on those portions until they are clean. There is a fine scum which is not apparent when the pavements are dry but rises up in a thin sheet of mud when moist, making the pavements very slippery. This and fine dust cannot be removed by hand cleaners, but by washing about twice a week in addition to hand cleaning, these troubles can be eliminated.
Very believes that this method of cleaning is fairly effective but is a dust raiser and the ability of the man to cover areas is very limited, especially since the automobile has come into such general use, as it interferes with the sweeper and his work. He says that there are hand machine brooms built on the principle of the carpet sweeper which are not dust raisers and which as a matter of fact do much more effective work. The pan scraper is only valuable to remove manure and mud and coarse litter, and its use should be limited to the time necessary for such work, and the broom used for dust removal.
The area a sweeper can clean depends upon the existence of local conditions. A test was made in New York City for one week and it was found that the area one sweeper was able to clean in a day of eight hours varied from 2,212 square yards to 16,075 square yards, with an average over the whole city of 5,745 square yards. The efficiency division of the Civil Service Commission of Chicago reports: “From an analysis of the findings of the time and motion studies of street cleaners the following table has been deduced, upon which are based the relative difficulty of cleaning different pavements under varyingconditions and the standard and equivalent areas to be cleaned by one man in one eight-hour day.”
In Philadelphia, which cleans its streets by contract, block men are assigned to sections designated by the chief. The area to be covered depends upon the character and amount of traffic. The duties of block men consist in patrolling the areas, gathering all papers and refuse and sweeping dirt as fast as it accumulates, and putting it into dust proof bags ready for loading into special wagons and hauling to a dumping station. The equipment used in hand patrol work consists of hand machines, bag carrier, burlap sacks, push brooms, hand scrapers, special cans and shovels. The dirt collected is placed in sacks and left at convenient points to be collected by special wagons and taken to the dump in sacks, these being returned by the drivers. Sacks are used in preference to cans because of the weight, bulk and noisiness of the latter.
Machine sweeping and cleaning is almost universally condemned, although this method is used in many cities. The machine broom is preceded by a sprinkling cart to loosen the filth and in a measure to prevent the dust rising. This is seldom effected. A broom is found to cover about 40,000 square yards per eight hours. The material is swept into windrows at the side and finally delivered to a windrow in the gutter, where it is picked up. The efficiency of therotary broom system is considerably reduced because the sweepers meet continual obstructions in busy streets and when operating over paved streets the brooms remove the coarser fragments of dirt only and leave the finer particles on the pavement.
Where the rotary broom is preceded by a street sprinkler, the dust forms into mud and clings to the surface of the pavement, and where the pavement is rough the mud is forced into the joints between paving blocks. As the street becomes dry, the dirt pulverizes and appears again as a dust nuisance. In all but one instance machine sweepers have been dispensed with in Chicago. South Water Street, the heavy wholesale fruit district of the city, is badly congested during the day, which makes it impossible effectively to clean this district by the “block” system. This street becomes very dirty during the day and is covered with a thick layer of dirt and débris at night. In this instance, the broom machines appear to be effective and give fairly good results in the cleaning of this coarse material.
The Chicago Commission believes that the mixing of calcium chloride with the water which is sprinkled in the different sections of the city would greatly add to the effectiveness of street cleaning and eliminating the perils of dust.
According to Very horse drawn brooms of the rotary style are not as effective as the hand broom.
Whinery says, “Sweeping by power sweepers at intervals of one or more days, while less expensive is far less effective and satisfactory than hand sweeping, though if properly done and supplemented by sprinkling with water or oil at intervals sufficiently near together to prevent dust flying it serves a good purpose.”
J. W. Paxton is of the opinion that the machine broom raises so much dust that heavy sprinkling is required. The fine dust mixed with water produces mud which is smeared on the street by the broom and when this becomes dry itturns to dust again. The broom sweeps only the coarser particles and many of these are thrown over the broom by centrifugal force to the pavement again.
In Philadelphia, machine broom cleaning is done in batteries of two or three, preceded by sprinklers, the number of brooms in each battery depending upon the width and character of the streets to be cleaned. The average gang consists of two machine brooms and one sprinkler, and four to seven broomers and a sufficient supply of wagons to remove the refuse, the number depending upon the haul to the dump and season of year, together with amount and character of traffic.
An investigation made by the Milwaukee Bureau of Municipal Research into the cost of rotary broom service brought out the following facts: In industrial and outlying residential section and upon streets adjacent to wharfs, where pavements are constructed of brick, sandstone, limestone or granite, the rotary brooms are usually used. The process is done nightly and to prevent dust, a sprinkler is used in advance of broom.
The following analysis of the cost of operation has been made by the Bureau: