A San Francisco sweep
In 1929, the Street Cleaning Division of the San Francisco Department of Public Works ceased using horse-drawn equipment to keep its streets clean. Instead, the department used 28 motorized trucks, each with a 15- to 20-yard capacity, an increase from the previous vehicles, which had a capacity of four to six yards, according to the July 1929 issue of The American City. During that time, cleaning San Francisco’s streets involved two systems. The block system used four trucks to collect street sweepings from 500 metal cans placed throughout the downtown area. The gang system was used in residential districts where workers shoveled refuse directly from the street onto one of 24 trucks. All of the division’s trucks were equipped with a hydraulic metal body, hoist and tailgate, and sliding doors on the body kept collected street sweepings hidden. Maintained by the public works department, the trucks were cleaned each night.
Today, operating on a 24 hour-a-day, seven-day-a-week schedule, the department runs a fleet of 50 mechanical street sweepers. The vehicles also are used for special events, such as parades and for paving and construction. The program also includes a roving crew that cleans city “hotspots,” such as outside night clubs, and flushers for washing the steets. To protect the environment, the department also has begun using clean air sweepers, which operate similarly to the traditional street sweepers. Each year, the department cleans 100,000 miles of Bay Area streets.