Arizona State and Local Government Documents Collection

The objective of this study was to evaluate the effect of typical chemical winter maintenance practices on Arizona Department of Transportation pavements. A review of previous studies on the effect of deicing/anti‐icing chemicals did not yield definitive recommendations, especially for DIAICs typically used by ADOT. Researchers conducted a laboratory study evaluating the effects of magnesium chloride, potassium chloride, sodium chloride, and distilled water on eight different open‐graded rubber‐modified asphalt concrete mixes using the boiling test. All experimental factors were found to be statistically significant, and the researchers provide recommendations on which DIAICs should be used for different binder and aggregate types.

Land Use and Traffic Congestion is an investigation into the links among land use, travel behavior, and traffic congestion. Researchers focused on four transportation corridors in the Phoenix area: three older neighborhoods with relatively mixed, higher density land use, and one suburban area with lower density but high traffic volumes. The analysis suggested that the higher density corridors exhibited less congestion due to the greater mix of uses, shorter trip lengths, more travel by transit and non-motorized modes, and the presence of a secondary street grid system.

The report provides a suite of recommended strategies to reduce single-occupant vehicle traffic in the urban areas of Phoenix and Tucson, Arizona, which are presented as a travel demand management toolbox. The toolbox includes supporting research on how to deliver, monitor, and fund implementation of the strategies, and a framework for the development of performance measures to assess their effectiveness. The research effort included studies of travel behavior in Phoenix and Tucson, reviews of best-practice measures nationally, and those in use in Arizona today, and interviews with local and national TDM professionals.

Some freeway users complain that new freeway segments fill up with traffic during peak hours immediately after construction. Because of this concern, the debate about the costs and benefits of freeways often centers on relieving congestion. The literature states that the long-term relief of congestion is an elusive goal. While congestion is a pervasive feature of freeways, it does not mean that constructing them is useless. This study helps to demonstrate that the great benefit of freeways is to facilitate travel rather than reduce peak-hour congestion. The study finds that the facilitated travel far outweighs the cost of freeway construction. Even if new freeway capacity becomes congested during peak travel hours, there is still great benefit in the increased travel mobility that can be accommodated.

As part of the Long Term Pavement Performance (LTPP) Program, the Arizona Department of Transportation constructed 19 Specific Pavement Studies 6 (SPS‐6) test sections on Interstate 40 near Flagstaff. The SPS‐6 project studied the effect of specific rehabilitation treatments on jointed portland cement concrete pavement (JPCP) performance. The test sections had various JPCP surface preparations, including crack and seat, minimum and maximum restoration, rubblization, asphalt concrete (AC) with fabric, and asphalt rubber with conventional AC. Opened to traffic in 1991, the project was monitored at regular intervals until 2002. Surface distress, profile, and deflection data collected throughout the life of the pavement were used to evaluate the performance of various flexible pavement design features, layer configurations, and thickness. This report documents the analyses conducted as well as practical findings and lessons learned that will be of interest to ADOT.