Road Manager
by Ruth W. Stidger, Editor-in-Chief

Sweeping City Streets: the Best Practices

Street sweeping can eat as much as 25% of street maintenance costs, so using best practices can pay big dividends.

Using best practice methods, you can improve drainage controls and reduce costs.

Street sweeping wears many faces. Some towns and cities do it with their own crews. Others use contractual services. Still others do little sweeping, particularly in residential areas.

Why sweep your streets? There are many reasons:

	Sweeping removes metal, glass, and other road hazards.
	Sweeping protects your drainage and water systems from debris and contaminants.
	Sweeping makes the streets and the municipality look good — helping attract new business and tourists, as well as keeping residents happy.

Modern methods

Vacuum sweepers are today’s equipment of choice, removing more than 90% of even fine materials, according to the University of New Hampshire Technology Transfer Center. Brush-type mechanical sweepers can pick up as little as 15% of fines by comparison.

Vacuum sweepers also collect solids before they get into the drainage system, reducing water pollution. Use your newest, highest-tech sweepers in areas with the greatest pollutant loads, environmental engineers advise.

Avoid water-flushing combined with sweeping when debris may be flushed into the drainage system, since water use can wash pollutants into drains. Sweepers that wet the surface to facilitate debris pickup without heavy flushing work well.

Best practice methods include use of a computerized database and street map to show work schedules and details.

Schedules can be developed based on the amount of material collected during previous sweeps.

Plan sweeps before water-system flushing or catch-basin cleaning. Sweeping first will reduce catch-basin cleaning costs.

Sweep streets that have been salted and sanded during winter maintenance operations as early as practical to prevent these materials flowing into the drainage system.

Sweep residential streets in the spring to remove sand and salt and in the fall to remove leaves.

Crew scheduling is most efficient using longer shifts, such as 10 hours four days per week.

Some cities use double shifts in the early spring to reduce salt and sand movement into the drainage system.

Costs

Fremont, California officials say that street sweeping takes a quarter of its in-house street maintenance budget. The city spends $1 million and 9,900 hours per year to sweep. Streets are swept once a month.

Crews and equipment make up most of street-sweeping costs, with the price tag for a sweeper running from $60,000 to $180,000. A conventional sweeper lasts about four to five years according to the Storm Water Center. Vacuum-assisted sweepers have about an eight-year life.

A mechanical sweeper’s initial cost lies toward the bottom of the price range; while vacuum-assisted sweepers cost from $150,000 to $180,000.

Sweeper rental costs range from $58 per hour for a 3-cubic yard-hopper unit to $88 an hour for a 9-cubic yard-hopper sweeper — operator not included — says the California Stormwater Best Management Practices Handbook.

A study of costs in Livonia and Plymouth Township, Michigan gives an average curb-mile sweeping cost of $68.

Sound practices

Beyond Boston’s Big Dig, Massachusetts uses street sweeping as a way to improve water quality on the Lower Charles River.

The U.S. Geological Survey developed a Stormwater Management Model for the watershed, which includes simulated effects of street sweeping in single-family, land-use areas.

According to research presented by Phillip Zarriello, Robert Breault, and Peter Weiskel, the model was used to check four sweeper efficiencies at varying frequencies of use, ranging from every day to every 30 days.

Resulting reduction (due to sweeping) of pollutants ranged from 14 to 44% for suspended solids, 11 to 34% for lead, 5 to 14% for phosphorus, and 1.4 to 17% for fecal coliform bacteria.

The study looked at types and efficiencies of sweepers, focusing on vacuum-assisted models as the best way to remove potentially contaminating pollutants. For example, the Northern Virginia Planning District Commission earlier found that a dry-vacuum-assisted sweeper picked up about 140% more debris than a mechanical sweeper and about 45% more material than a regenerative air sweeper.

Other studies report that vacuum-assisted sweepers can pick up as much as 98% of the total loose street dirt.

A Canadian report by R.C. Sutherland and S.L. Jelen says that a vacuum-assisted sweeper removes 87% of solids when streets are swept twice a week; 51% if they are swept monthly.

Street curbs catch much street debris. According to the Northern Virginia Planning District Commission, 90% of roadside dirt accumulates within 12 inches of the curb.

The Federal Highway Administration suggested eliminating curbs in some cases to allow street dirt to move onto lawns. However, this also allows easy movement of water and resulting erosion after heavy storms.

Streets with large pavement cracks and broken areas reduce effectiveness simply because dirt lodges in hard-to-reach areas.

Multiple sweeping passes were used by the Washington State Department of Ecology in a test. Solid removal went from 50% with one pass to 75% with two passes — using a mechanical sweeper.

San Diego sweeps residential as well as commercial streets, operating on a monthly cycle.

The city tries to avoid parked-car problems, which reduce sweeping efficiencies, by posting no-parking signs for the sweeping day, i.e. the first Monday of the month.

In Dana Point, California, streets are swept weekly to reduce pollutants and prevent them entering the ocean.

Debris collection went from 23 tons per month to 46 tons per month when the weekly schedule went into effect.

Lincoln, Nebraska uses a more limited program, which is fairly common for towns and cities not on a body of water. It sweeps residential streets three times a year. The spring, summer, fall schedule targets collection of left-over winter sand and gravel and leaves.

St. Louis follows a similar schedule and residents commonly sweep or rake leaves into their street expecting the city to take care of the debris.

During its sweeping season of early April until December, Portland, Maine sweeps streets one or two times a month depending on traffic volume. Debris is deposited in a landfill.

San Jose, California outsources sweeping of residential and central business district streets, which are swept on a monthly schedule. City crews sweep arterials weekly.

Click Here to return to article index