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. 14.7 yds 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¢.
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.