Minutes - Public Works Committee - 05/21/2002

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Councilmember Hendriksen inquired as to what it cost the City to sweep the roads. Principal City Engineer Olson replied that there is no cost to sweep the unpaved roads, but the City does have to do more cleaning the ditch systems to maintain drainage in the areas of unpaved roads. The reason the paved roads are swept is to make sure that sand and slat don't get into the drainage system. He noted that both of those maintenance issues are covered by the Storm Water Utility fund, which is why those issues were not included in the report. City Engineer Jankowski stated that a comparative analysis of the taxpayer expense associated with the maintenance costs over a thirty-year period was done. The analysis is based on a half- mile of roadway, which might be typical of 156th and 157th Avenues between Variolite and Armstrong Boulevard. Mr. Jankowski reviewed the typical maintenance requirements for each type of street noting that in actual practice it is not unusual to deviate from this typical schedule for paved road maintenance. Similarly, dirt road maintenance is closely tied to the number of rainfall events, which occur between March and November, which can also vary from year to year. The comparative financial analysis is based on two primary unit costs. The unit costs for seal coating and overlays are $0.85 per square yard, and $3.30 per square yard, respectively. These unit prices are the current costs, including both construction and project overhead, based on the City's experience with its annual street maintenance program. The dirt street maintenance is based on the current charge rate for the use of the City's grader operation at $100 per hour. The results of the analysis show that over a period of thirty years, the total number of City dollars spent on dirt street maintenance is 88 percent of that projected for paved streets. However, since there is a significant difference in the cash flow expenditure between these processes, annual versus periodic, it is useful to also compare them using a present worth analysis. Present worth represents the amount of money that would be needed at the onset of the thirty-year period to pay all expenditures with the unspent balance earning interest at a specified rate. A zero balance would remain after the 30~year period. Based on a present worth analysis, dirt street maintenance is between 112% to 115% as costly as paved street maintenance, using 6% and 8% interest rates respectively. It was pointed out that the idealized schedule provided for bituminous street maintenance has not always been realized because of budget limitations and pavement ratings. A second method of comparing the relative costs of the two types of street maintenance, which would more accurately reflect the actual costs experienced in the past, could be based on analysis of benefit the City contributes per unit on an annual basis. Mr. Jankowski reviewed the unit benefit analysis for both dirt and paved streets noting that the analysis shows that over the last nine year period the contribution of the City on a per unit basis for dirt streets has been 178% of that for paved streets. In the future this unit benefit for dirt streets would be expected to remain constant (excluding inflation). The future trend for paved streets is somewhat more difficult to predict. On one hand, the increasing number of overlays will cause this unit benefit to increase. Conversely, the increasing percentage of smaller sized lots, which consequently require smaller amounts of pavement per unit, will tend to lower the benefit. Councilmember Hendriksen inquired as to how much of the cost for grading is actual grading time and how much is transport time. Public Works Committee/May 21, 2002 Page 5 of 12