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On a peak day, New York City's Department of Sanitation deploys 354 mechanical sweepers to pick up a substantial portion of the 100 tons of litter deposited daily on the city's 6,000 street miles. Field studies conducted by the department indicated that the major obstacle to doing a thorough job of cleaning was the number of illegally parked cars blocking the curb. We used Monte Carlo simulations to determine the increase in sweeping effectiveness that could be expected from significant reduction in illegally parked cars. The simulations provided information that was critical to the decision making process and resulted in the redeployment of 30% of the city's mobile traffic enforcement agents. The redeployment led to fewer illegally parked cars and more curb space available for cleaning. [ABSTRACT FROM AUTHOR]

Management science has played a critical role in increasing the ability of New York's Department of Sanitation to clean the city's streets. Not only has the department achieved five consecutive years of improved cleanliness ratings (currently at 68.7 percent acceptably clean from a low of 53 percent), but current ratings are near record levels (72 percent) with 700 fewer cleaners than we had when we last achieved those record ratings. To achieve ratings equal to the highest ever recorded we will need approximately 400 fewer cleaners than we used to have. A savings of 400 cleaners is equivalent in financial terms to $12 million a year in salaries and fringe benefit costs. [ABSTRACT FROM AUTHOR]