Constructability and Productivity Analysis for Long Life Asphalt Concrete Pavement Rehabilitation Strategies

A large portion of the highway system in the United States has exceeded its design and its service life. Deterioration of the existing highway system adversely affects the safety of road users, ride quality, the operational cost of vehicles, and the cost of highway maintenance. This report presents the results of a constructability and productivity analysis for the Caltrans Long Life Asphalt Concrete Pavement Rehabilitation Strategies (LLACPRS), focusing on optimizing the maximum production capability within a 55-hour weekend closure.With the assistance of California asphalt concrete paving contractors, the constructability analyses explored the effects of the following parameters: rehabilitation materials, design profile [Crack Seat and Overlay (CSOL) and Full-Depth Asphalt Concrete (AC) replacement of different thickness], cooling time, number and capacity of construction resources, and alternative lane closure strategies. The experiment design consisted of a hierarchical structure of rehabilitation options based on consultation with industry and Caltrans.Prototype constructability analysis programs running on commercial spreadsheet software were developed to interactively link all factors involved in the rehabilitation processes. The analysis programs were designed to help road agencies and paving contractors determine which rehabilitation and construction strategies were the most feasible in an urban environment with the underlying goal of balancing the maximization of production capability and minimization of traffic delay. The asphalt constructability analysis procedure has been implemented for both deterministic and stochastic analyses.The asphalt concrete constructability analyses indicate that the proposed objective of Caltrans to rebuild 6 lane-kilometer of truck lanes within a 55-hour weekend closure has a low probability of success. Material delivery resources, especially dump trucks for demolition and delivery trucks for asphalt concrete supply, were the major constraints limiting the production. The total layer thickness for asphalt concrete proved to be a major determining element on the production capability. For example, the production capability of Full-Depth AC Replacement is just about 60 percent of CSOL production within a weekend closure for a scenario in which the two truck lanes need to rehabilitated. However, CSOL requires rehabilitation of all lanes including shoulders on both sides, thereby limiting its effective productivity. Different rehabilitation working methods, determined by the construction access, lane closure tactics, and paving procedures, also have a significant effect on the production capability of the rehabilitation.The comparison of different construction windows, (i.e., a weekend closure versus continuous closure) was also examined to see the effect of different construction windows on production capability. Continuous closure/continuous operation enables the CSOL project to be finished 15 percent faster and the Full-Depth AC Replacement project to be finished 12 percent faster compared to weekend-only closures. However, the total duration of the closure for continuous closure/daytime operation was longer than that for the weekend-only closure. This study concludes that efficient lane closure tactics designed to work with the pavement profile can minimize non-working time, such as the time waiting for the AC to cool, and increase the production capability of the project. The constructability analysis for AC developed in this study will aid transportation agencies in their decision-making processes for prioritizing the number of rehabilitation projects on their backlogs, selecting optimal strategies, and effectively communicating project duration with the public and other project stakeholders, such as local governments.