Pavement Preservation Program Research Articles

Decision Trees for Selecting Asphalt Pavement Crack Sealing Method

Crack sealing is an important preventive treatment in the pavement preservation program. To achieve a cost-effective crack seal, it is crucial to select a proper crack sealing method. In Minnesota asphalt pavement cracks are sealed using both the clean-and-seal and rout-and-seal methods; however, there is no guideline for choosing the most suitable crack sealing method. This study deals with a literature review, an online survey, crack seal performance data collection, cost-effectiveness analysis of the crack sealing methods, life cycle cost analysis, and development of two decision trees to aid in selecting the most suitable crack sealing method. The first, which can be used in the pavement management system, needs information such as crack severity, pavement type (new versus overlay), pavement analysis period and design life, traffic level, and crack seal sequence (first, intermediate, or last). The second decision tree, which is a simplified version of the first and can be used by preventive maintenance crews, requires less information, such as crack severity, traffic level, and place in the crack sealing sequence.

Subsurface Condition Evaluation of Asphalt Pavement for Pavement Preservation Treatments

Abstract The Indiana Department of Transportation (INDOT) has developed a guideline for evaluation of subsurface condition, a project-level evaluation for applicability of Indiana pavement preservation treatments (PPT). The developed guideline, using ground penetration radar (GPR) measurements, surface distress, and laboratory tests, determines the pavement subsurface distress severity and its distribution. The guideline also incorporates the newly developed water stripping severity test utilizing the digital image processing. The guideline has hierarchal evaluation system based on the type of data available for the test section. Level 1 is selected if GPR analysis data is available, level 2 is selected if surface distress data is available, and level 3 is used for all other cases. In addition, the subsurface distress distribution analysis tool (DCUAL) provides the locations of the PPT applicable sections. Case studies were conducted to provide aid to better understand the guideline, to present the example evaluation results upon the application of the guideline, and to validate the applicability of guidelines. Three test roads treated with PPTs within two to three years in Indiana were selected, and different evaluation levels were applied to the test roads. Level 1 and level 2 were applied for state road (SR) SR-70, and level 2 and 3 was applied for SR-257 and SR-43, respectively. Level 1 and level 2 analyses in the case study showed a good agreement with the case of the non-uniform subsurface distress distribution. In the process of determining the PPT applicability, pavements with the overall score of 60 or higher were found to be suitable for PPTs for all three levels of analysis and suitable for the Indiana State Roads having average annual daily traffic of less than 9000. Overall, the case study validated that the guideline provides a consistent, rational, and data-driven decision-making process for the applicability of the project-level pavement preservation program.

Performance and Benefits of Michigan Department of Transportation's Capital Preventive Maintenance Program

The Michigan Department of Transportation's (DOT) pavement preservation program dates back to 1992. In Michigan, pavement preservation is implemented primarily through the Michigan DOT's capital preventive maintenance (CPM) program, in which preventive maintenance treatments are used to protect existing pavement surfaces, to slow deterioration, and to correct surface deficiencies. An overall objective of the CPM program is to postpone major rehabilitation and reconstruction activities by extending the service life of pavements. Results of a study performed to calculate the benefits and costs of various preventive maintenance treatments used in the Michigan DOT's CPM program are presented. With benefit defined as the percentage increase in performance over a do-nothing or untreated pavement performance curve where data were available, benefits were calculated for preventive maintenance treatments. Benefit–cost ratios were calculated by unit cost, and permitted the comparison of the cost-effectiveness of similar treatments. The overall performance of the Michigan DOT's CPM program was also examined by comparing the life-cycle costs of a rehabilitation strategy to a preservation strategy with the use of a simplified approach. The outcome showed that the preservation strategy resulted in agency cost savings of approximately 25% per lane mile over a rehabilitation-only strategy. Findings from this study can be used to help the Michigan DOT improve its CPM project selection, treatment selection, and performance monitoring and modeling practices.

Development of Enhanced Alaska Pavement Preservation Program and Strategy Selection Guide

The Alaska Department of Transportation and Public Facilities (DOT&PF) wished to enhance its existing pavement preservation management program by using effective pavement preservation treatments for cold regions. This initiative would extend pavement life and defer the need for more costly rehabilitation. By collaborating with the California Pavement Preservation Center and the Alaska University Transportation Center, the Alaska DOT&PF recently completed a pavement preservation research project to improve its pavement preservation program for flexible pavements. Research tasks included conducting an international survey of pavement preservation in cold regions, reviewing literature on cold region pavement preservation treatments, monitoring existing preservation treatments that Alaska used, developing a pavement preservation database, and creating an online computer program for treatment selection. The database for pavement preservation treatment tracking is a web-based online program that includes standard types of pavement preservation strategies used in Alaska; pavement construction, traffic, weather, and other performance-related information; an integrated Google Map function to show the location of pavement preservation projects; and multiple pavement condition survey results with supporting documents. The strategy selection program is integrated within the pavement preservation database. The program sees results of the survey and other information on Alaska treatments to conduct treatment strategy selection and life-cycle cost analysis. Workshops have been given on preservation treatments used in cold regions and use of the database and strategy selection process. Tools developed for the Alaska DOT&PF should be helpful for long-term implementation of an effective pavement preservation program. Other agencies could learn from Alaska's experience.

Bituminous Surface Treatment Protocol for the Washington State Department of Transportation

To help the Washington State Department of Transportation (WSDOT) enhance its pavement preservation program through an improved understanding of the use of bituminous surface treatment (BST), the Highway Development and Management System was used as an analytical tool to test the average annual daily traffic and equivalent single-axle load levels appropriate as criteria for selecting the application of BST resurfacings to WSDOT pavements. It verified the feasibility of using BSTs to maintain pavements with higher traffic levels than have been applied in the past. Results also suggested that alternating the application of BST resurfacings and 45-mm hot-mix asphalt overlays is an effective rehabilitation strategy. Finally, the study results were used to estimate the impacts that increased use of BST surfaces would have on the performance of the state-owned route system.

Cost-Effective Preventive Maintenance: Case Studies

With most of the highway systems in place, emphasis has shifted from design and construction to preservation and expansion. Unfortunately, the engineering skills, knowledge, and experience required to preserve the systems are significantly different than those required to originally design and build the systems. The experience gained in the initial phase, although important, is not in itself sufficient to preserve the systems. Pavement preservation is defined as the sum of all activities undertaken to provide and maintain serviceable roadways. This includes corrective maintenance and preventive maintenance, as well as minor rehabilitation projects. A cost-effective pavement preservation program requires a systematic and comprehensive engineering management of, and a solution to, pavement network problems. Preventive maintenance (PM) is defined by AASHTO as the “planned strategy of cost-effective treatments to an existing roadway system and its appurtenances that preserves the system, retards future deterioration, and maintains or improves the functional condition of the system (without increasing the structural capacity).” Hence, PM actions must be taken on pavements in relatively good condition. The development and implementation of a cost-effective PM program faces several obstacles: political debate, budget constraints, lack of education, and the existing practice of “worst pavements are first.” Some state highway agencies have overcome these obstacles, and they are harvesting the success of their PM programs. The state of the practice of three agencies—those of Arizona, Montana, and Pennsylvania—is presented and discussed.

Construction and Performance of an Ultrathin Bonded Hot-Mix Asphalt Wearing Course

In recent years, the need for preserving the investment in the U.S. highway system has received increased emphasis. An effective pavement preservation program includes several maintenance strategies that are applied in a cost-effective and efficient manner. Several new technologies have been developed to address these problems. One of the more promising technologies is the use of an ultrathin bonded hot-mix asphalt (HMA) wearing course (UTBWC). It consists of a layer of HMA laid over a heavy asphalt emulsion layer or membrane. The thickness of the ultrathin surface ranges from 9.5 to 19 mm (3/8 to ¾ in.). The system is placed on a structurally sound rigid or flexible pavement, which may exhibit minor surface distresses. The process was developed in France in 1986 and has been in use in the United States since 1992. Published experimental project reports and inspections of recently completed projects in many locations indicate good performance of the UTBWC. It provides a surface with excellent macro texture qualities, good aggregate retention, and excellent bonding of the very thin surfacing to the underlying pavement.

Development of a Knowledge-Based Formula to Prioritize Pavement Rehabilitation Projects

The development of a formula to prioritize pavement rehabilitation projects based on experts’ opinion is presented. This formula is used for the preparation of the Arizona Department of Transportation (ADOT) 5 yr pavement preservation program. The knowledge to determine the prioritization formula and treatment assignment criteria was captured from a group of experts using a survey design based on the rational factorial methodology. The survey questionnaire provided a set of pavement sections with different characteristics and asked the experts to indicate which sections should receive a rehabilitation treatment, what type of treatment they would recommend for each section, and which priority should be assigned to the resulting preservation project. Eight pavement characteristics (functional classification, geographical region, structural number, traffic, pavement rideability, cracking, rutting, and average maintenance cost for the past 3 yr) were identified as influence variables. A fractional factorial experiment design with four blocks was selected for the study. A questionnaire with a different set of pavement sections was prepared for each experimental block. The questionnaires were sent to pavement experts from ADOT headquarters and maintenance districts. The responses were analyzed, using linear regression analysis, to select the best models for the priority and treatment selection equations. The study showed that the rational factorial methodology is a powerful tool for capturing and quantifying expert opinions. The average opinion of the experts surveyed indicated that rutting, functional classification, roughness, cracking, traffic, and maintenance cost significantly influence the priority assigned to a preservation project. The treatment assignment model was less reliable; a larger panel of experts would be required to obtain a reliable model.

Expert Project Recommendation Procedure for Arizona Department of Transportation’s Pavement Management System

The Arizona Department of Transportation (ADOT) uses a network-level pavement management system to determine budget requirements for its annual pavement preservation program. Although this is a valuable tool for preservation programming, it does not assist the engineers with the selection of projects and rehabilitation treatments. The documented research was designed to enhance the capability of ADOT’s pavement management system to include project selection. An automatic project recommendation procedure was developed and implemented in a user-friendly, modular computer program. This automatic system is expected to reduce considerably the effort required to develop the preservation programs. It should improve the consistency of the decision process. The analysis starts with a section delineation procedure that delineates uniform roadway sections. It then computes the remaining service life of each uniform section by using linear performance equations and trigger points defined for each condition indicator. An artificial neural network simulator is used to screen and recommend roadway sections for the preservation program. The trained artificial neural network prepares a list of candidate sections, using the criteria learned from past selections and the current condition of all pavement sections. This preliminary list of candidate sections is further analyzed by a project recommendation procedure. This procedure recommends a preservation treatment, assigns a priority rating to each section in the list, and sorts the projects by priority. Funding is assigned to the highest-priority sections within each roadway group until the budget recommendation provided by the network optimization process is reached.

Artificial Neural Network for Selecting Pavement Rehabilitation Projects

The use of an artificial neural network simulator to develop and implement an automatic procedure for screening and recommending roadway sections for pavement preservation is described. This procedure is part of an automatic project recommendation procedure extension of the Arizona Department of Transportation's (ADOT's) pavement management system. The output of the recommendation procedure is a list of candidate projects for consideration in the 5-year pavement preservation program. The artificial neural network simulator was used to “learn” the knowledge from historical project selection. The neural network was trained with the pavement condition and characteristics and the sections selected for the ADOT's pavement preservation program for several years. The trained neural network predicted a correct output for 100 percent of the training facts and 76 percent of the testing examples. Further refinements of the artificial neural network architecture should result in better-performing networks. The artificial neural network analysis reduces the level of effort required to identify candidate sections for the pavement preservation program, reduces subjectivity, and minimizes the probability of missing sections that should be programmed.

Artificial Neural Network for Selecting Pavement Rehabilitation Projects

The use of an artificial neural network simulator to develop and implement an automatic procedure for screening and recommending roadway sections for pavement preservation is described. This procedure is part of an automatic project recommendation procedure extension of the Arizona Department of Transportation's (ADOT's) pavement management system. The output of the recommendation procedure is a list of candidate projects for consideration in the 5-year pavement preservation program. The artificial neural network simulator was used to learn the knowledge from historical project selection. The neural network was trained with the pavement condition and characteristics and the sections selected for the ADOT's pavement preservation program for several years. The trained neural network predicted a correct output for 100 percent of the training facts and 76 percent of the testing examples. Further refinements of the artificial neural network architecture should result in better-performing networks. The artifi...