Khaled Ksaibati

Rubblization of Concrete Pavements

The Florida Department of Transportation is in the process of evaluating rubblizing concrete pavements as an effective rehabilitation technique for eliminating reflected cracks in asphalt overlays on top of concrete pavements. As part of that evaluation, a nationwide survey was performed to gather information about the practices of other departments of transportation with regard to rubblization and to determine the overall performance of rubblized sections in various states. The survey indicated that most states have a relatively small number of rubblized sections, with the exception of three states that have more than 10 sections each. The construction techniques, overlay thicknesses, and field performance varied from state to state. However, it was clear that most states are highly satisfied with rubblization as a good means for eliminating reflected cracks. Only a few states indicated problems with rubblization, mainly due to weak subgrade.

Evaluation of Moisture Susceptibility of Asphalt Mixtures Containing Bottom Ash

Bottom ash, as a by-product of coal-fired electric power plants, has recently been used in constructing transportation facilities. However, the use of bottom ash in asphalt mixtures is still in an early stage. The moisture resistance of asphalt mixtures containing bottom ash, which has not been adequately researched, is investigated in this study. Eight asphalt mixtures produced with one type of asphalt cement, two types of aggregate, three sources of bottom ash, and lime additive were evaluated using the principles in AASHTO T283. Analysis of test data indicated that granite mixtures had higher tensile strength values than did limestone mixtures in dry conditions. Addition of lime or bottom ash did not substantially change these values. All mixtures tested met the Superpave volumetric mix design requirement of tensile strength ratio (TSR) after one freeze–thaw cycle. The addition of lime significantly improved the moisture resistance of the asphalt mixtures as measured by the TSR. With lime addition, aggregate type, bottom ash addition, and bottom ash source were all insignificant with respect to TSR. On the basis of TSR rate (TSRR), the addition of lime significantly improved the moisture resistance of the asphalt mixtures subjected to multiple freeze–thaw cycles. Without lime addition, bottom ash played a role similar to that of lime in improving the TSRR for the materials tested.

Method for Assessing Heavy Traffic Impacts on Gravel Roads Serving Oil- and Gas-Drilling Operations

In cooperation with the Wyoming Department of Transportation and Sheridan, Johnson, and Carbon Counties, the Wyoming Technology Transfer Center conducted a 3-year pilot asset management program. These counties were chosen because of significant impacts on their road networks from oil- and natural gas–drilling activities. One objective of the program was to assess the impacts of drilling activities on the counties’ roads, with the hope that decision makers would achieve a better understanding of these impacts; this assessment is described. Improvements were recommended for roads with inadequate surface conditions for their functional class. The costs of recommended improvements were examined for both the roads that serve predominantly drilling activities (drilling roads) and the rest of the counties’ roads (nondrilling roads), along with the distresses driving the recommendations. From a comparison of the rate at which improvements were recommended on the drilling and nondrilling roads, conclusions were drawn about the impacts of drilling traffic. The portion of roads in substandard condition is much higher for drilling roads than for nondrilling roads. Clearly, the heavy traffic associated with drilling activities has significantly damaged these three counties’ roads beyond what would be anticipated from typical traffic loads. The proposed method could easily be adapted to other road systems experiencing a significant influx of heavy truck traffic to assess the impact of the additional traffic.

Performance of Recycled Asphalt Pavement in Gravel Roads

Because more recycled asphalt pavement (RAP) has become available to use in roadways, the Wyoming Technology Transfer–Local Technical Assistance Program Center and two Wyoming counties saw a need to investigate the use of RAP in gravel roads. The Wyoming Department of Transportation along with the Mountain Plains Consortium funded this study. The investigation explored the use of RAP as a means of dust suppression while considering road serviceability. Test sections were constructed in the two counties and were monitored for dust loss by means of the Colorado State University dustometer. Surface distress evaluations of the test sections were performed following a technique developed by the U.S. Army Corps of Engineers in Unsurfaced Road Maintenance Management (Special Report 92–26). The data collected were statistically summarized and then analyzed. The performance of RAP sections was compared with that of gravel control sections. This comparison allowed fundamental conclusions and recommendations to be made for RAP and its ability to abate dust. It was found that RAP-incorporated gravel roads can reduce dust loss without adversely affecting the roads serviceability. Other counties and agencies can expand on this research to add to the toolbox for dust control on gravel roads.

Gravel Roads Surface Performance Modeling

Twenty gravel road study sections at 10 sites in north-central Wyoming were monitored from September 2005 through June 2006. Windshield or mobile, visual survey ratings of the sections and field measurements were taken weekly. Surfacing gravel samples were collected, and their gradations were determined. Traffic speeds and volumes by class were collected with a two-tube system. (A two-tube system counts traffic by receiving signals from two tubes placed 8 ft apart across the road. By a comparison of the times at which signals are received from each tube, the speed of the traffic can be determined, as can the number and spacing of axles.) Statistical analyses generated regression models that allowed the prediction of the service life of an unmaintained gravel road. Traffic speeds, traffic volumes, and surfacing gravel properties were shown to have the greatest influence on gravel roads’ deterioration rates. For these typical Wyoming county roads with good geometry, good drainage, and adequate gravel thicknesses, the typical failure mode was shown to be either potholes or washboards (corrugations). The typical life of gravel roads without maintenance was shown to be in the range of several months to 1 year. Climatic effects were shown to be related to precipitation more than seasonality, at least in Wyomings dry–freeze climate.

Annualized Road Works Cost Estimates for Unpaved Roads

Providing locally elected officials with reasonable information about the cost of maintaining and improving an unpaved road network is part of the job for those directly responsible for maintaining such a network. This paper describes a simple method for generating estimates of the annualized maintenance and construction costs incurred by small agencies, three Wyoming counties in this case. Several simple inputs are used to estimate the total annualized cost of operating an unpaved road network. Road segments are assigned to one of four functional classes. Treatment costs and frequencies are determined for each functional class. These inputs are used to generate annualized network-level cost estimates for each county. The most difficult aspect of this procedure is generating reasonable treatment cost and frequency information, particularly for rehabilitation and reconstruction costs. The process of generating these inputs, along with the process of assigning roads to functional classes, is described in this paper. Comparisons between the estimates generated using the method presented in this paper and actual costs incurred by two of the counties both demonstrate the feasibility of this method and highlight aspects of this procedure that will benefit from further refinement. Tailoring treatment costs and frequencies to in-place cost tracking methods will make for more precise projection of future costs, particularly for maintenance tasks. The methods presented here are particularly useful for smaller agencies without the resources to undertake highly sophisticated, expensive asset management programs. This methodology may be applied to a wide and diverse range of agencies.

Field and Laboratory Evaluations of Hot-Poured Thermoelastic Bituminous Crack Sealing of Asphalt Pavements

This paper describes the results of field and laboratory tests evaluating four configurations and three materials used for crack surfacing. Crack surfacing, as defined in this paper, is the sealing of cracks over 1 in. (25 mm) wide in asphalt pavements. Laboratory testing using the thermal stress restrained specimen test (TSRST; AASHTO TP 10-93) determines the temperature at which a specimen with its ends restrained fails due to thermal contraction. Field studies evaluate the performance of two materials with the uniform overband configuration on three roads in Wyoming. All crack surfacing materials are commercially available hot-poured thermoelastic bituminous products. Overband configurations are found to be the preferred method for applying crack surfacing, based on the TSRST. Failure modes are evaluated and generally found to propagate from the interface between the surfacing material and the pavement to which it is bonded. Field studies indicate that traffic and snowplowing have a significant influen...

PAVEMENT ROUGHNESS DATA COLLECTION AND UTILIZATION

The Florida Department of Transportation (FDOT) is in the process of evaluating the protocols for collecting and analyzing roughness data. As part of that evaluation, a nationwide survey was performed to identify the trends and practices of various departments of transportation with regard to roughness data collection and analysis. All responding states indicated interest in obtaining the results of the survey, which was mailed to all 50 state departments of transportation. The responses show that most states are using laser-type road profilers for roughness measurements. The international roughness index (IRI) is the most widely used roughness index. Highway Performance Monitoring System (HPMS) data from different states are collected by using different equipment, and the data are collected in various wheelpaths and filtered differently. Stricter guidelines should be developed to ensure the consistency of HPMS data.

Indian Reservation Safety Improvement Program: A Methodology and Case Study

The need to reduce fatal and injury crashes on tribal lands has been recognized for years. The United States has realized a decline in fatal crashes over the past several years, but fatal crashes continue to increase on tribal lands. Little progress has been made in improving safety on tribal lands. Limited resources, lack of coordination across jurisdictions, the rural nature of many of the roadways, and lack of crash data have made it difficult for tribes to implement an effective safety improvement program. A methodology that can address these challenges is presented in this paper. The proposed methodology has been implemented successfully in the Wind River Indian Reservation in Wyoming. Collaboration among safety stakeholders—state departments of transportation, tribal leadership, the Local Technical Assistance Program, the Tribal Technical Assistance Program, the Bureau of Indian Affairs, and local and tribal law enforcement—is key to the success of such a process.

Implementation Guide for the Management of Unsealed Gravel Roads

To address the current lack of a gravel roads management system (GRMS) appropriate for the rural agencies of the Intermountain West and the Great Plains, the Wyoming Technology Transfer Center (T2/LTAP) consulted with a volunteer group of experts and practitioners in the fields of unsealed earth and gravel roads and roadway management to put together a set of recommendations and guidelines for managing unsealed roads. This paper describes and summarizes the gravel roads management methodology developed by T2/LTAP under the guidance of this group. Steps in implementing a GRMS are described, beginning with an assessment stage in which an agency evaluates its current unsealed roads information management and the resources available to improve it. Next, three elements of a GRMS are described: data management, inventory, and data collection. Eight maintenance tasks for unsealed roads are described: blading, reshaping, regraveling, dust control, stabilization, isolated repairs, major work, and drainage maintenance. Primary outputs of a GRMS are described, including cyclic maintenance scheduling, triggered maintenance scheduling, and network-level outputs, including network-level monitoring, financial tables, and road tables and maps. Safety and drainage assessments are described briefly. Recommendations are made for putting these procedures into practice.