Book Description

The continued preservation of ADOT's pavements becomes an ever- increasing issue as non-renewable resources such as mineral aggregate become more and more difficult to obtain. Historically, ADOT's design philosophies have resulted in strategies that consist primarily of mill and fill and overlay. These pavement strategies are designed for approximately a ten year life, at which time, another similar treatment would be performed. Proper design philosophies evaluate life cycle costs to select the best available design option. However, the life cycle cost consists of both the construction cost and the user cost incurred by the public through delay, etc. While construction costs are easily defined, user costs are very difficult to quantify and often times may actually exceed the actual cost of the facility being constructed. Since the user costs are not directly borne by the agency, it becomes somewhat of a philosophical discussion as to what user costs should be considered. In recent times, mineral aggregate sources have become increasingly more difficult to obtain in Arizona. However, our current design philosophies and economics requires needing new materials approximately every ten years. There is a need to consider reconstruction of significant roadways so that they can obtain design lives, perhaps as many as thirty to forty years before rehabilitation or reconstruction.