Kelly L Smith

Pavement Preservation on High-Traffic-Volume Roadways

Extending the life of roadway pavements with the timely use of preservation techniques has been an important strategy for highway agencies for many years. However, although preservation strategies for low- to moderate-volume roadways are widely accepted, are fairly commonplace, and have generally been successful, implementation of those same strategies on high-traffic-volume roadways involves greater challenges. The SHRP 2 Project R26 was performed to examine pavement preservation strategies for high-traffic-volume applications and to develop guidance on which preservation treatments are appropriate under what circumstances. In this project the state-of-the-practice for preservation approaches for high-traffic-volume roadways was identified through a national and international literature search and a detailed survey of highway agencies and other pertinent organizations. This project also involved developing a set of best practices and guidelines for selecting preservation treatments at the project level on the basis of careful and complete assessments of factors such as traffic volume, pavement condition, climatic condition, costs, expected performance, and work zone requirements. This paper presents findings from the highway agency survey and discusses how those results were used in conjunction with the literature review results to develop the key deliverable for the study: the stand-alone document Guidelines for the Preservation of High-Traffic-Volume Roadways.

Texturing of Concrete Pavements

This report presents a recommended process for determining the type of concrete pavement texture that should be used for a specific highway project. The process considers the effects of texture type on friction and noise characteristics. The report will guide pavement and construction engineers in identifying and specifying textures for concrete pavements that will provide adequate surface characteristics. The information contained in the report will be of immediate interest to state engineers and others concerned with concrete pavement design and construction.

Cost-Benefit Analysis of Continuous Pavement Preservation Design Strategies Versus Reconstruction

The Arizona Department of Transportation (ADOT) has traditionally employed continuous pavement preservation as part of an overall design strategy to maintain the highest levels of service for highway users. Concerned about the effects of continual weakening of substructure material layers on preservation treatment cost and performance (i.e., more extensive and more frequent preservation activities), ADOT sponsored a study to determine the cost-effectiveness of the continuous preservation approach as compared with a reconstruction strategy. One goal of the study was to determine the break-even point for the two strategies (i.e., after how many rehabilitation treatments reconstruction becomes as cost-effective as continuous preservation). With inputs such as (a) service life estimates, (b) best estimates of unit costs, (c) work zone-related user costs, and (d) the typical analysis period and discount rate used by ADOT, the total life-cycle costs for four alternative strategies were determined and compared for the 15 commonly occurring pavement scenarios in Arizona. The results of the analysis showed a consistent reduction in total life-cycle costs as the number of rehabilitation treatments performed between original construction and reconstruction increased from none to two. Results also showed that for nine of the 15 scenarios, total life-cycle costs associated with the third reconstruction alternative (two rehabilitations occurring prior to the first reconstruction event) were within 3% of the total life-cycle costs of the continuous preservation strategy. Hence, the break-even point occurs when two to three rehabilitation treatments are performed prior to reconstruction.

Role of Stabilized and Drainable Bases in Early-Age Cracking on Concrete Airfield Pavements

A strong body of emerging evidence shows that under certain circumstances concrete pavements constructed over certain types of bases have a higher risk of early-age, uncontrolled cracking. In some cases, this has resulted in the removal and replacement of up to 5% to 7% of the total number of slabs paved on a project–an expensive proposition for the stakeholders. An investigation of nearly two dozen airfield pavement sections in the United States identified several plausible factors that act either independently or in concert with other factors and lead to this phenomenon. This study attempted to explain the interaction between factors that trigger slab movements (triggers) and key design, material, and construction factors (variants) that aggravate the impact of these movements on early cracking risk. On the basis of this study, guidelines for design, materials selection, and construction of rigid pavements on stabilized and drainable bases were developed to mitigate the impact of various factors on the early-age cracking phenomenon. Revisions were suggested to the FAAs specifications for lean concrete, cement-treated, and hot-mix asphalt bases. New specifications were developed for permeable bases that balance stability with drainability.

Quality Assurance Procedure to Assess Maintenance Adequacy of Drainage Assets

The engineering community has long recognized the need for adequate maintenance of drainage structures. However, despite several regional and national studies that highlight the damaging effects of poor maintenance, few agencies have improved their inspection and maintenance schedules. Although inadequate funding is the most plausible reason for this scenario, the lack of formal procedures to survey drainage assets, determine their conditions vis-à-vis their functional objectives, and objectively quantify their condition also adds to the problem. Described is a practical prototype maintenance quality assurance (QA) procedure for evaluating the adequacy of drainage asset maintenance in a consistent manner. Key components of the QA procedure are discussed in detail. A software program developed to implement the various components of the QA procedure is described. The program is a simple tool with which to check the condition and functionality of drainage assets at any time. Designed to handle both surface and subsurface drainage assets, the program can be implemented at any level of maintenance jurisdiction. A complete description of the program’s functionality, from the selection of inspection units to the generation of maintenance quality ratings, is provided. Implementing the presented concepts could result in a substantial economic benefit for the implementing agency.

Smoothness Index Relationships for HMA Pavements

A recent Federal Highway Administration survey indicated that 48 states and Puerto Rico use smoothness specifications for hot-mix asphalt (HMA) pavement construction. As this is a relatively new concept, many states have adapted the Portland cement concrete pavement specifications of Profile Index using the standard 5-mm blanking band for use on HMA pavements. However, the blanking band may not provide a reproducible or portable smoothness measure for HMA pavements because of the technical limitations of the equipment and procedures. The International Roughness Index (IRI) or the Profile Index using a 0.0-mm blanking band seem to provide a more repeatable and portable standard. However, one barrier to move widespread implementation of these new smoothness standards is the lack of objective, verifiable correlation methods for use in establishing specification limits using the IRI or blanking band. Assistance in selecting appropriate IRI and blanking band specification limits is needed to provide a basis for modifying current specifications to these more reproducible and portable smoothness indices. This research effort has developed a relationship between IRI and PI that can assist in transitioning to a reproducible and portable initial IRI or PI smoothness specification for HMA pavements.

Developing a Correlation Between the Pavement Condition Ratings Used by Five Federal Lands Management Agencies

The Federal Highway Administration’s Office of Federal Lands Highway works closely with its federal and tribal transportation partners, collectively called Federal Lands Management Agencies (FLMAs). A review of the various pavement condition assessment methods used by five of the FLMAs showed that each one was different and that there was no uniform basis to compare pavement conditions on a national basis. This paper presents the results of a study performed to develop statistical models to crosswalk the paved road condition ratings of the National Park Service, the U.S. Forest Service, the U.S. Fish and Wildlife Service, the U.S. Army Corps of Engineers, and the Bureau of Land Management. To achieve this objective, two major field studies involving independent condition assessments of several federal lands roads by the FLMA representatives were conducted. The results of the field studies and the subsequent analyses of data demonstrated that the individual rating procedures used by each FLMA could be reasonably crosswalked to the pavement condition index (as specified by the ASTM D6433 standard), allowing for a consistent method of reporting FLMA pavement conditions nationally.

Analyzing Hot-Mix Asphalt and Portland Cement Concrete Highway Construction Using Probabilistic Optimization for Profit

Contractors constantly have to make decisions about maximizing profits while considering risks associated with choosing construction target levels for various acceptance quality characteristics (AQCs). With more and more states adopting incentive–disincentive pay adjustment provisions for quality as measured by various AQCs, a contractor likely has to evaluate several options before selecting an optimum target quality that will maximize profit at an acceptable level of risk. The greater the number of AQCs, the more complex the assessment that the contractor is required to perform and the less intuition and experience can be relied on. The updated Probabilistic Optimization for Profit (Prob. O. Prof. 2.0) is a computer program used as a probabilistic-based tool designed to assist portland cement concrete and hot-mix asphalt paving contractors in evaluating statistical quality assurance specifications. In addition, it assists the highway agencies in evaluating the appropriateness of their specifications and ensuring that they have no undesirable consequences. This procedure allows the agency to adjust pay factors accordingly while developing specifications. The Prob. O. Prof. 2.0 program is discussed, and examples of its use are provided.

Impact of Increasing Roadway Construction Standards on Life-Cycle Costs of Local Residential Streets

With increasing damage due to the combination of increasing traffic load applications, adverse climate, and increasing frequency of trench cutting and patching associated with utility work, residential streets are requiring more frequent, extensive, and costly maintenance and rehabilitation (M&R) to maintain adequate levels of serviceability during pavement design life. Increased cost of M&R and eventual reconstruction are an added burden on already limited city budgets. To rectify this situation, city managers and engineers are looking at enhancing current structural design standards for residential streets to increase their load-carrying capacity. With an increase in load-carrying capacity, it is hoped that frequency of M&R will be reduced and the design life of such pavements will be extended. However, adopting a higher design standard has significant cost implications. The question then becomes, Will the expected increase in initial cost be offset by the significant decrease in M&R costs and corresponding increase in pavement life that will delay eventual reconstruction? The Minnesota Department of Transportation (DOT), on behalf of the Local Road Research Board, initiated a study to evaluate the impact of enhancing residential street pavement design standards to accommodate greater axle loads on life-cycle costs. The primary focus was to compare the life-cycle costs of residential streets designed using Minnesota DOTs 5- to 7-ton and 9- to 10-ton design standards. The study concluded that life-cycle cost for the 5- to 7-ton and 9- to 10-ton design standards was not significantly different at the 95% significance level.

Part 2: Pavements: Impact of Increasing Roadway Construction Standards on Life-Cycle Costs of Local Residential Streets

With increasing damage due to the combination of increasing traffic load applications, adverse climate, and increasing frequency of trench cutting and patching associated with utility work, residential streets are requiring more frequent, extensive, and costly maintenance and rehabilitation (M&R) to maintain adequate levels of serviceability during pavement design life. Increased cost of M&R and eventual reconstruction are an added burden on already limited city budgets. To rectify this situation, city managers and engineers are looking at enhancing current structural design standards for residential streets to increase their load-carrying capacity. With an increase in load-carrying capacity, it is hoped that frequency of M&R will be reduced and the design life of such pavements will be extended. However, adopting a higher design standard has significant cost implications. The question then becomes, Will the expected increase in initial cost be offset by the significant decrease in M&R costs and correspon...