Nevada Department Of Transportation Research Articles

Identification of Graffiti Countermeasures for Highway Facilities

In recent years, the budget for removing graffiti from the highway systems maintained by the Nevada Department of Transportation (NDOT) has been steadily increasing. In order to mitigate the graffiti problem and be able to efficiently utilize its resources for the prevention of graffiti, NDOT initiated a study to compile an inventory of graffiti prevention countermeasures employed by the state Department of Transportation (DOT) in the U. S., and evaluate the effectiveness of these countermeasures. To this end, a questionnaire was developed and was sent to all state DOTs. This paper presents the results of the survey and offers some observations

Evaluation of Rut Resistant Asphalt Mixtures for Intersection

ABSTRACT The Nevada Department of Transportation (NDOT) sponsored a two-phase research study to develop specific requirements to be used for HMA mixes at intersection. The phase i of the study evaluated the impact of different aggregate gradations on the mixtures' resistance to rutting. The rutting resistance of a HMA mix was found to be highly dependent upon the aggregate gradation. The phase II consisted of a laboratory evaluation of the mixes with the most promising gradations identified in phase i for fatigue cracking resistance. Additionally, a full mechanistic analysis is conducted to effectively evaluate the relative fatigue and rutting performances of the evaluated HMA mixes under heavy braking 18-wheel truck. Based on the data generated in this study a new aggregate specification limit was recommended for asphalt mixtures at intersections. The recommended gradation is intended to improve the asphalt mixture's resistance to rutting without jeopardizing its resistance to fatigue cracking.

Evaluation of Rut Resistant Asphalt Mixtures for Intersection

ABSTRACT The Nevada Department of Transportation (NDOT) sponsored a two-phase research study to develop specific requirements to be used for HMA mixes at intersection. The phase i of the study evaluated the impact of different aggregate gradations on the mixtures' resistance to rutting. The rutting resistance of a HMA mix was found to be highly dependent upon the aggregate gradation. The phase II consisted of a laboratory evaluation of the mixes with the most promising gradations identified in phase i for fatigue cracking resistance. Additionally, a full mechanistic analysis is conducted to effectively evaluate the relative fatigue and rutting performances of the evaluated HMA mixes under heavy braking 18-wheel truck. Based on the data generated in this study a new aggregate specification limit was recommended for asphalt mixtures at intersections. The recommended gradation is intended to improve the asphalt mixture's resistance to rutting without jeopardizing its resistance to fatigue cracking.

Performance Evaluation of Asphalt Pavement Preservation Activities

A 2-year research project was sponsored by the Nevada Department of Transportation (NDOT) and conducted by University of Nevada at Reno researchers to evaluate the long-term performance of asphalt pavement preservation activities that NDOT has implemented for the past 15 years. During this research project, 11 preservation activities were identified after several meetings with NDOT maintenance personnel. This study evaluated 847 field sections. The performance of the selected field sections was assessed on the basis of the pavement condition before and after treatment application. The analysis evaluated the likelihood of enhancing the pavement performance as well as the anticipated performance period for the various treatments. Benefit–cost ratios for the various treatments were also evaluated, given the pretreatment pavement condition, traffic level, and environmental conditions. A set of guidelines is provided to help select the most cost-effective preservation activities on the basis of the most favorable conditions with regard to environment, traffic, and conditions of the existing pavement (e.g., present serviceability index, international roughness index, rut depth, fatigue cracking, transverse cracking, and block cracking).

Investigation and Implications of Mechanically Stabilized Earth Wall Corrosion in Nevada

The Nevada Department of Transportation has more than 150 mechanically stabilized earth (MSE) walls at 39 locations. Wall reinforcement corrosion was found by accident during construction projects at two of these locations. The resulting investigations of these walls produced direct measurements of metal losses and electrochemical properties of the MSE-reinforced fill. One MSE wall was replaced with a cast-in-place concrete tie-back wall at great expense. A statistical analysis addresses the variability in measured corrosion and electrochemical data to predict corrosion behavior. The original MSE-reinforced fill approval electrochemical test results are significantly different from those measured in postconstruction investigations. A correlation has been developed between two distinctly different soil resistivity test methods: the Nevada T235B and AASHTO T-288 methods. Overprediction made by the Nevada T235B method has proven detrimental to the service lives of MSE walls. The internal stability analyses (using AASHTO 2007 load and resistance factor design specifications) of two remaining MSE walls at an intersection were also performed by using metal loss models developed from the statistical analysis. The findings of the study were subsequently extrapolated to other Nevada MSE walls. Through review of the reinforced fill approval data, suspect Nevada MSE walls have been identified relative to estimated reinforced fill aggressiveness.

Multi-criteria decision analysis for the selection of a near road ambient air monitoring site for the measurement of mobile source air toxics

In 2002, the Sierra Club legally challenged the US Federal Highway Administration and the Nevada Department of Transportation’s National Environmental Policy Act environmental document related to the proposed widening of US 95 in Las Vegas, Nevada, including the assessment of impacts of mobile source air toxics from the proposed project. To resolve the situation, Federal Highway Administration entered into a Settlement Agreement with Nevada DOT and the Sierra Club, wherein the Administration agreed to undertake a research effort to characterize the impact and behavior of particulate matter with aerodynamic diameter less than 2.5 μm and mobile source air toxics near highways. The US Federal Highway Administration and US Environmental Protection Agency determined that it would be in the best interest of both organizations to implement this project in a collaborative manner, allowing a more effective utilization of staffing and resources. One of the first steps of the project implementation has been the selection of a suitable ambient air monitoring site in or around Las Vegas, Nevada. This article presents the multi-criteria analytical steps taken to select the near road monitoring sites to provide air quality data needed to support environmental decision-making in this project.

Long-Term Performance of Reflective Cracking Mitigation Techniques in Nevada

Hot-mix asphalt (HMA) overlay is one of the commonly used methods for rehabilitating deteriorated pavements. The Nevada Department of Transportation (DOT) uses HMA overlays as a rehabilitation technique for the majority of the state's flexible pavements. One major type of distress influencing the life of an overlay is reflective cracking. In the past, Nevada DOT has experimented with a number of techniques— such as cold in-place recycling, reinforced fabrics, stress relief courses, and mill and overlay—to reduce the impact of reflective cracking on HMA overlays. Several projects were constructed under each category. The long-term field performance of various Nevada DOT reflective cracking mitigation techniques was evaluated; the techniques were used on flexible pavements at 33 field projects. Performances of the various projects were analyzed by fatigue, transverse, and block cracking measurements from Nevada DOT's pavement management system data. In addition, the statistical approach called principal component analysis was used to asses the effectiveness of each of the reflective cracking techniques. The study indicated that cold in-place recycling and mill and overlay were the most effective treatments for reflective cracking of HMA overlays over HMA pavements under Nevada's conditions, except when the existing pavement experiences severe alligator cracking. In such situations, it is recommended that HMA pavement be subjected to reconstruction or full-depth reclamation.

Alternative Strategies for Rehabilitation of Low-Volume Roads in Nevada

An overview of the attempt by the Nevada Department of Transportation (NDOT) to find alternative rehabilitation strategies to rehabilitate its low-volume road network effectively is provided. Because of Nevada's continuing growth, NDOT is faced with the challenge of how to balance its available funding between pavement preservation and capacity improvement projects. NDOT is responsible for 13,000 lane miles of roadway, of which 3,385 lane miles (26%) qualify as low-volume roads. The low-volume roads have a two-directional average daily traffic of 400 or less. Five roadway projects with a combined total of 111 centerline miles were rehabilitated with 29 combinations of structural and surface strategies. The rehabilitation strategies investigated included full-depth reclamation with lime, cement, asphalts, and foamed asphalt. Various cold-mix, cold-in-place recycling with millings and different rejuvenating agents, and surface treatment test sections were constructed. The constructability issues that were reported during construction are discussed. In addition, pavement condition is examined and laboratory testing is reviewed. Results suggest that NDOT can use alternative rehabilitation strategies in place of its conventional method of 2-in. plant-mix bituminous surface overlay and chip seal to rejuvenate its low-volume roadway network. A cost saving of approximately $100,000 per centerline mile is anticipated.

Hot-Mix Asphalt Mixtures for Nevada's Intersections

The overall objective of this research was to identify a hot-mix asphalt (HMA) mixture with good resistance to rutting and shoving at intersections to be used in the southern part of the state of Nevada. For that purpose, two laboratory evaluations were conducted: (a) evaluation of mixtures from in-service intersections and (b) laboratory evaluation of mixtures with different aggregate gradations. In the first part, field cores from 13 different projects cut from rutted and nonrutted intersections in southern Nevada were investigated in the laboratory to evaluate and compare the volumetric and gradation properties of the mixtures. In the second part, five aggregate gradations were selected for laboratory evaluation on the basis of past performance and results from the first part of this study. On the basis of the analysis of the data generated in this study, the aggregate gradation from the intersections that experienced no rutting showed the best performance in all the permanent deformation tests conducted in this experiment. In addition, the specifications used by the Nevada Department of Transportation for various permanent deformation tests were reviewed, and adjustments have been suggested for the HMA mixtures that are to be used at intersections. Interpretations from dynamic mechanistic analyses of pavements under heavy loads at intersections (with and without interface shear stresses) and laboratory behavior of HMA mixtures were used to arrive at these recommendations.

Cold In-Place Recycling and Full-Depth Reclamation Projects by Nevada Department of Transportation

One of the biggest challenges that public agencies face is how to optimize available funding. With the price of bituminous materials 70% higher than 2 years ago and increased demand for capacity improvement projects, it is more important than ever to use in-place materials when rehabilitating pavement structural sections. Cold in-place recycling (CIR) and full-depth reclamation (FDR) are two pavement rehabilitation strategies that the Nevada Department of Transportation (NDOT) has used for more than 20 years. These strategies have allowed NDOT to save more than $600M over the past 20 years compared with complete reconstruction costs. In addition, traffic interruptions are minimized during construction, and natural resources are preserved. According to the Highway Performance Monitoring System data, NDOT has the highest percentage of its combined National Highway System Interstate and other roadways rated in the “good” category. The reason for this achievement is that NDOT uses a proactive Pavement Management System (PMS) to prioritize its pavement preservation projects. A considerable amount of CIR and FDR rehabilitation work is performed in conjunction with the proactive PMS. Because these strategies are more cost-effective than overlay, mill and overlay, or reconstruction, NDOT can rehabilitate more roads with less money. This report will describe how to select, design, and construct successful CIR and FDR projects. The performances of the strategies are evaluated, and life-cycle cost analysis is developed to demonstrate the cost–benefit of CIR and FDR versus conventional rehabilitation strategies.

Cold In-Place Recycling and Full-Depth Reclamation Projects by Nevada Department of Transportation: State of the Practice

One of the biggest challenges that public agencies face is how to optimize available funding. With the price of bituminous materials 70% higher than 2 years ago and increased demand for capacity improvement projects, it is more important than ever to use in-place materials when rehabilitating pavement structural sections. Cold in-place recycling (CIR) and full-depth reclamation (FDR) are two pavement rehabilitation strategies that the Nevada Department of Transportation (NDOT) has used for more than 20 years. These strategies have allowed NDOT to save more than $600M over the past 20 years compared with complete reconstruction costs. In addition, traffic interruptions are minimized during construction, and natural resources are preserved. According to the Highway Performance Monitoring System data, NDOT has the highest percentage of its combined National Highway System Interstate and other roadways rated in the good category. The reason for this achievement is that NDOT uses a proactive Pavement Managem...

Pavement Management System Based On Financial Consequence

One of the biggest challenges for any public organization is how to prioritize projects to maximize existing funding. With so many programs competing for the same funding, it is especially important to optimize pavement rehabilitation programs to allow for funding for other programs, such as safety, capacity improvements, and environmental improvement projects. This report describes how the Nevada Department of Transportation (NDOT) optimized its available funding while improving pavement condition by using an eight-step pavement management system based on financial consequence. This eight-step procedure includes administration support, contract database implementation, roadway system division, performance models, project prioritization, and strategy selection. This procedure can easily be adopted by other states. A nominal amount of information is required to initiate this system, and the reward can be exceptional. NDOT saves $42 million a year with this methodology. An advantage of a pavement management system based on financial consequence over a conventional network optimization system is that process allows engineers to communicate with top administrators in a nontechnical way. Administrators can understand the concept and make good roadway funding choices without needing a great deal of technical input from engineers. For example, administrators see that the cost of delaying a 10-mi roadway section on an Interstate system by 2 years can cost the agency an additional $6 million for rehabilitation; but that delaying a 10-mi roadway section on a relatively low-volume road can cost only a few thousand dollars.

Pavement Management System Based on Financial Consequence

One of the biggest challenges for any public organization is how to prioritize projects to maximize existing funding. With so many programs competing for the same funding, it is especially important to optimize pavement rehabilitation programs to allow for funding for other programs, such as safety, capacity improvements, and environmental improvement projects. This report describes how the Nevada Department of Transportation (NDOT) optimized its available funding while improving pavement condition by using an eight-step pavement management system based on financial consequence. This eight-step procedure includes administration support, contract database implementation, roadway system division, performance models, project prioritization, and strategy selection. This procedure can easily be adopted by other states. A nominal amount of information is required to initiate this system, and the reward can be exceptional. NDOT saves $42 million a year with this methodology. An advantage of a pavement management system based on financial consequence over a conventional network optimization system is that process allows engineers to communicate with top administrators in a nontechnical way. Administrators can understand the concept and make good roadway funding choices without needing a great deal of technical input from engineers. For example, administrators see that the cost of delaying a 10-mi roadway section on an Interstate system by 2 years can cost the agency an additional $6 million for rehabilitation; but that delaying a 10-mi roadway section on a relatively low-volume road can cost only a few thousand dollars.

Evaluating Field Performance: Case Study Including Hot Mix Asphalt Performance-Related Specifications

State highway agencies strongly desire to develop and use performance-related specifications (PRS) for highway construction. A PRS for hot mix asphalt (HMA) construction, titled HMA Spec, was recently developed as part of the WesTrack project. The beta version of HMA Spec was applied to compare pay factors and actual rutting performance to predicted performance for four Nevada Department of Transportation (NDOT) test sections on Interstate 80 (I-80) east of Reno, Nevada. Some of these sections were similar in terms of materials and construction techniques to coarse-graded sections constructed at WesTrack, so a comparison to performance at WesTrack was also made. NDOT placed the test sections on I-80 in an effort to assess the applicability of the Superpave mix design process and HMA Spec for Nevada’s conditions. Sections were designed using both Hveem and Superpave mix design methods. Several interesting observations were made while evaluating the HMA Spec output. These observations and field performance data are described in this paper.

Field and Laboratory Performance of Superpave Mixtures in Nevada

The Nevada Department of Transportation (NDOT) has strongly supported Superpaver-related research and implementation efforts since the completion of the Strategic Highway Research Program. However, it is one of the state highway agencies that has not implemented use of the Superpave mix design system. Instead of rapidly implementing Super-pave in the mid-1990s, NDOT chose to build field test sections composed of Superpave and the mixtures conventionally used at the time (Hveem) and placed side-by-side to evaluate the Superpave system relative to the system in use. Extensive laboratory evaluations were conducted on the materials and mixtures placed on each section, and field performance was monitored over time. This study presents a synopsis of the field and laboratory performance information gathered over the past 6 years. Planned NDOT evaluations of Superpave mixtures based on the findings of this effort to date are outlined.

Performance of Cold In-Place Recycling in Nevada

In light of the increasing cost of hot-mix asphalt (HMA) mixtures and the limited availability of good materials, cold in-place recycling (CIR) offers an attractive alternative for rehabilitating asphalt pavements. Because of its limited performance history and the unavailability of a standard mix-design procedure, the use of CIR mixtures has been limited to low-and medium-volume roads. For more than a decade, many highway agencies have experimented with or used CIR mixtures and reported numerous successes. The Nevada Department of Transportation (NDOT) is currently using CIR on low- and medium-volume roads. The CIR layer is treated as a stabilized base course followed by a thin HMA overlay. As part of this program, NDOT developed a mix-design procedure based on the Hveem mix-design method to establish the optimum moisture and emulsion contents. The design procedure evaluates the moisture sensitivity of the CIR mixture and determines the need for lime treatment of the CIR mix. The basic concept of the mix design is to assess the ability of the CIR process in providing a flexible and stable mix that can withstand the combined action of traffic loads and environment. The designed CIR mixtures were implemented on three field projects and showed excellent performance, which led NDOT to construct additional CIR projects.

Refinement of Superpave High-Temperature Binder Specification Based on Pavement Performance in the Accelerated Loading Facility

Various parameters have been proposed to refine the current Superpave® high-temperature binder specification. One parameter relates the phase angle (δ) directly to accumulated strain from the creep–recovery test. Another variation suggests a formula to predict the accumulated strain using the current Superpave parameters G* and sin δ. Recently, NCHRP 9–10 project suggested a criterion based on a parameter derived from Burger’s viscoelastic model. In Europe, zero-shear viscosity is being proposed as a high-temperature specification parameter. These and other criteria proposed for high-temperature specification are evaluated by examining the correlation of each criterion to pavement performance. The experimental design consists of five asphalt binders used in the FHWA’s accelerated loading facility. Additionally, two binders used by the Nevada Department of Transportation in construction of 1–80 test sections were tested. Results show that the zero–shear viscosity correlates reasonably well with performance and is the best parameter among those evaluated. However, accurate determination of the zero-shear viscosity is time-consuming and requires expensive instrumentation, which makes it unsuitable as a specification parameter. Therefore, an easy method of obtaining zero-shear viscosity was evaluated and found to correlate to performance equally well. In this method, data from a single frequency sweep at the specification temperature are used to estimate the zero-shear viscosity. This method can be implemented immediately with little or no training or need for new instrumentation.

Effectiveness of Lime in Hot-Mix Asphalt Pavements

The pavement community has recognized that moisture damage of hot-mix asphalt (HMA) has been a serious problem since the early 1960s. Numerous additives have been evaluated with the objective of reducing the potential of moisture damage in HMA mixtures; lime has been one of the most common ones. The Nevada Department of Transportation has been using lime in HMA mixtures since the mid-1980s. The objective of this research was to quantify the improvements in pavement performance that have been realized through the addition of lime to HMA mixtures. The program evaluated field samples and pavement performance data from untreated and lime-treated pavements. The properties of untreated and lime-treated mixtures from field projects in the southern and northwestern parts of Nevada indicate that lime treatment of Nevada's aggregates significantly improves the moisture resistance of HMA mixtures. The study showed that lime-treated HMA mixtures become significantly more resistant to multiple freeze–thaw cycles than do the untreated mixtures. Long-term pavement performance data indicate that under similar environmental and traffic conditions, the lime-treated mixtures provide better-performing pavements with fewer requirements for maintenance and rehabilitation activities. The analysis of the impact of lime on pavement life indicates that lime treatment extends the performance life of HMA pavements by an average of 3 years. This extension represents an average increase of 38% in the expected pavement life.

Influence of Hot-Mix Asphalt Parameters on the Correction Factors of the Ignition Oven Test

Abstract The ignition oven method has been gaining popularity because of its applicability to both laboratory and field conditions, its nondependency on chemicals, and its ability to evaluate both binder content and aggregate gradations. However, the use of this method requires the careful determination of correction factors for both binder content and aggregate gradations. The need for such correction factors stems from the fact that most aggregates experience a certain level of weight loss as they are subjected to elevated temperatures. These weight losses must be accounted for in order to accurately determine the binder content and aggregate gradation of HMA mixtures. It is well accepted that the most important step of the ignition oven test is the determination of an accurate correction factor. The implementation of the ignition oven method requires the highway agency to assess the performance of the local materials with the test procedure and to identify the mixture parameters that significantly impact the determined correction factor. In preparation for the implementation of the ignition oven test, the Nevada Department of Transportation (NDOT) conducted an extensive laboratory testing program to assess the impact of the various mix parameters on the determination of the correction factors. The experiment included aggregate source, binder type, lime, and testing temperature. This paper analyzes the data generated from the NDOT experiment and evaluates the impact of each of the considered factors on the correction factor. In summary, the analysis of the data generated in the NDOT experiment showed that the aggregate source and the addition of lime have the most significant impact on the determined correction factor followed by the temperature and binder type. However, if during a field project the binder or the method of lime application changes, this change would not require the determination of a new correction factor. The data also showed that the blank aggregate method would generate correction factors that are less variable than the known asphalt content method.

Development of Performance Models Based on Department of Transportation Pavement Management System Data

The Nevada Department of Transportation (NDOT) is developing a network optimization system (NOS). The objective of the system is to evaluate various alternatives and to recommend the most cost-effective rehabilitation treatment to be used on the various sections of the state highway system. The NOS consists of several subsystems, including performance models, life-cycle cost analysis, and network optimization. Performance models have been developed for the rehabilitation treatments most commonly used by NDOT: overlay and mill/overlay. The performance models were developed on the basis of the pavement management system data that have been collected by NDOT for the last 15 years. The models were generated through statistical analyses that related the present serviceability index to age, traffic, environment, and structural and materials properties. First cost and annual maintenance cost figures were established to be used in the life-cycle cost analysis. The annual maintenance costs proved to be the most difficult figures to estimate due to the extremely large variability. After several attempts, the fixed period cumulative cost approach was identified as the best alternative to reducing the variability of the annual maintenance costs. In order to accomplish true network optimization, the entire NDOT highway system was subdivided into project segments (total number of segments is in excess of 800). Several databases were formed to house the data corresponding to each project segment. The NOS will use the performance models in conjunction with the supporting databases to conduct a fully automated optimization analysis.