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51 Life Cycle Cost Discussion Based on information available to the'fask Force, life cycle costs for both concrete and asphalt pavements were found to be, essentially, equivalent. What that means is over the estimated 60 -year life of a pavement; the cost of construction, repair, and ongoing maintenance is the same. The simple comparison is this: • Bituminous pavement costs less initially, and costs more to maintain. • Concrete pavement costs more initially, and costs less to maintain. One of the inherent flaws with life cycle cost analysis is that it relies on the fact that maintenance costs are based on a strict repair regiment, in which repairs happen on a pre-set schedule. Cities inherit a certain amount of risk and potential reward when it comes to developing pavement management programs. The proposed life cycle maintenance activities make an assumption that all bituminous streets need to be overlayed after 20 years to maintain acceptable pavement ratings. Similarly, it assumes thatjoint rehabilitation will need to occur every 30 years for concrete pavements. However, there are instances where pavements may last longer and require less maintenance, thus reducing the overall life cycle costs. For instance, a bituminous pavement lasts for 28 years, and therefore only requires one overlay in its 60 -year life cycle instead of two. The opposite situation may also be true, in that a bituminous pavement may only last 15 years, and may require three overlays in its 60 -year life cycle instead of two. Similar examples can be made for concrete pavements. Concrete Panel Replacement Quantification As was noted in previous task force meetings, the cost to replace concrete panels in order to perform emergency utility repairs cannot be fully quantified, due to a variety of issues including the random nature of emergency utility repairs, the condition of the existing utilities, location of necessary repair, and the time of year a repair is necessary. Based on information provided by the City of St. Anthony's Public Work's department, and compared to information provided by the City of Edina, a reasonable assumption is that an average of 30 concrete panels per year will require replacement for utility repair (assume 20 panel replacements) and general subgrade and/or material failure (assume 10 panel replacements). Street Reconstruction Task Force Findings Report November 13, 2008 WSB Project No. 1626-03