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:
| Cost of machine | $250.00 | ||
| Depreciation of 10 per cent. on machine | $25.00 | ||
| Interest at 4½ per cent. | 11.25 | ||
| $36.25 | |||
| Minor repairs and replacements | |||
| 6 brooms at 50 lbs. bamboo | $20.00 | ||
| ea. at 8¢. per lb | 24.00 | ||
| 48 hrs. labor @ 24¢ hr | 12.00 | 56.00 | |
| $92.25 | |||
| 150 days operation | $0.615 | ||
| 2 sweepers at $2 per day ea. | 4.00 | ||
| Team and driver per day | 5.00 | ||
| Grease, etc. | 0.05 | ||
| $ 9.665 | |||
| Average yards cleaned, 40,000 | |||
| Average cost per 1,000 sq. yds., 24.1 | |||
| Combined with sprinkler | |||
| Sprinkler, team per day | $5.00 | ||
| Water | 0.90 | 5.90 | |
| 40,000 sq. yds. sprinkled, cost per 1,000 sq. yds | 14.7 | ||
| Broom cost per 1,000 sq. yds | 24.1 | ||
| Combined cost per 1,000 sq. yds | 38.8 | ||
| The assessment per front foot on a street 30 ft. wide and cleaned 50 times a season would be 3.2¢. | |||
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 surface of 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:
| Purchase price | $4,000 | |||
| Depreciation 50 per cent. | $2,000 | |||
| Interest 4½ per cent. | 180 | |||
| $2,180 | ||||
| Repairs (estimated) | 25 | |||
| Replacement of brooms, 30 @ $6 ea. | 180 | |||
| Labor making brooms | 60 | |||
| Yearly cost | $2,445 | |||
| 150 days operation, cost per day | $16.30 | |||
| 1 Chauffeur | $3.00 | |||
| 2 sweepers | 4.00 | |||
| 1½ time | 2.50 | |||
| Gasoline and oil | 1.25 | |||
| Water | .12 | $10.87 | 10.87 | |
| $27.17 |
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.