Browsing by Author "Virginia Tech Transportation Institute"

Now showing 1 - 20 of 337
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    30 Years – 20 State DOTs: Trends in Pavement Management observed through real world Implementation at the State DOT Level
    Zavitski, Jeffrey L.; Piane, Robert R. (2013-06-04)
    Since the first International Conference on Managing Pavement Assets 30 years ago in 1985, there has been continuous enhancement and evolution of pavement management system (PMS) technology to produce more effective recommendations coming out of an agency's PMS. Improvements in data collection, performance measures, deterioration modeling, dynamic segmentation, treatment algorithms, triggering mechanisms and optimization technologies have led to significant improvements in PMS strategy recommendations as well as the acceptance of those recommendations in both centralized and de-centralized State Departments of Transportation (DOT). Significant efforts have also been invested in methodologies and technologies to integrate PMS into an overall asset management system (AMS) at the State DOT level utilizing cross asset optimization technologies. This paper will examine the evolution of pavement management from the desktop environment to today's enterprise pavement management systems within 20 State DOTs that use a common software platform and present significant changes in pavement management methodologies that lead to increased use and acceptance of the PMS recommendations and adoption within the agency. It will also examine current trends that will impact the systems of tomorrow including integration with other decision making tools, capturing field data, and alternative approaches to optimization.
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    3D Mapping of Pavements: Geometry and DTM
    Laurent, John (2014-09)
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    3D Pavement Surface Macrotexture: Measurements And Friction Relationships
    Shalaby, Ahmed; El Gendy, Amin (2012)
    Pavement macrotexture is typically reported as mean profile depth over a standard base length. Recently, a new measurement method based on photometric stereo system was introduced. The method requires a minimum of three images of the surface that are illuminated from different directions and isolated from ambient lighting. The variation in intensity of the lighting is used to recover the 3D pavement surface. This paper discusses applications of the photometric stereo system as a new non-contact texture measurement method. The 3D pavement surface is analyzed in space and frequency domains. In frequency domain, the power spectrum energy which reflects the wavelength content of the surface model is introduced as an indicator of surface evenness. The relationship between friction and the 3D texture indicators is examined. The research shows that the texture indicators computed from the recovered surface provide new substantial information on the quality and condition of the riding surface.
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    9th International Conference on Managing Pavement Assets
    Virginia Tech Transportation Institute (2015-05)
    This conference program lists the events that took place during the 9th International Conference on Managing Pavement Assets (ICMPA9), which was held from May 18-21, 2015 in Alexandria, VA. The conference brought together pavement design and management engineers, companies specialized in providing pavement management services and data collection, researchers and specialists on asset/pavement management, general pavement/road engineers, planners dealing with the development of public works programs, and academics specializing in pavement design, analysis and management. The conference aimed to define the requirements for the "next generation" of pavement management tools need and to that effect it builds upon the following theme: "moving pavement management beyond the short-term: embracing innovation and addressing sustainability, accountability, and improved performance." ICMPA9 was organized by the Virginia Tech Transportation Institute, the Federal Highway Administration, the Virginia Department of Transportation, the American Association of State Highway and Transportation Officials (AASHTO), the Transportation Research Board, and the World Road Association.
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    About The Reproducibility Of Texture Profiles And The Problem Of Spikes
    Goubert, Luc; Bergiers, Anneleen (2012)
    The ISO working group ISO/TC43/SC1/WG39 has recently been worrying about the quality of texture profiles, measured with laser profilometers. It appears that the quality has not improved in recent years, rather on the contrary: in spite of the technological progress it appears to decrease! The WG is especially concerned of the presence of invalid positive spikes in some profiles which might dramatically affect the Mean Profile Depths (MPD) [1] and to some extent the texture spectra calculated with those spectra, if one does not properly deal with these erroneous measurement points prior to calculating the MPD or spectrum. In this paper the results of an international round robin test with static laser profilometer devices on two epoxy moulds of dense asphalt concrete road surfaces are shown, indicating the reproducibility of this kind of devices for the wavelength range from 2,5 mm up to 125 mm. A new procedure to deal with the spike problem is presented. The aim is to remove the spikes without affecting significantly the valid part of the spectra. The effect on MPD and spectra will be shown for some typical cases. The method, based on the detection of steep jumps in the profile, appears to work.
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    About The Rolling Resistance Trailer And Parameters Influencing Rolling Resistance
    Bergiers, Anneleen; Goubert, Luc; Vuye, Cedric (2012)
    The issue of global warming by an excessive amount of carbon dioxide (CO2) in the atmosphere is a hot topic and the consequences for man and environment become more and more clear. Road transportation plays a significant role in CO2 emission and unlike other sectors, its emission has even increased the last years. To stop this trend, different measures may be taken: e.g. tackling traffic congestion, lowering the consumption of the vehicles… Many other parameters influence CO2 emission by transportation: e.g. tyre, vehicle and road characteristics… In this paper the influence of the road surface is investigated with a “quarter-car” trailer, suitable to measure rolling resistance with a car tyre on different road surface types. Texture measurements with a laser profilometer are performed to examine the correlation between rolling resistance and texture. The impacts of different parameters are investigated: repeatability over short and long time, speed, wind, tyre inflation pressure, tyre load, tyre type … Some rough coast down measurements are performed to compare with the trailer method. By gaining more knowledge about this topic, more environmental friendly and sustainable road infrastructure may be developed and implemented. This is expected to be an important tool for policy makers in their fight against CO2 emission.
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    Accelerated Testing and Instrumentation: A Canadian Case Study
    Tighe, Susan L. (2015-06-04)
    The primary objective of this paper is to describe how the CPATT Test Track is used to advance Canadian pavement engineering practices through the investigation of the impact of axle loads and environment on flexible and rigid pavement structures. It also discusses how the Track is used as an educational tool for both undergraduate and graduate students. Since construction, over 1,000 undergraduate and graduates have not only visited the Test Track, but have used the data from the Test Track for course assignments and other research. It has been a valuable and strategic asset for both research and education.
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    Access Control Design on Highway Interchanges
    Rakha, Hesham A.; Flintsch, Alejandra Medina; Arafeh, Mazen; Abdel-Salam, Abdel-Salam Gomaa; Dua, Dhruv; Abbas, Montasir M. (Virginia Center for Transportation Innovation and Research, 2008-01-01)
    The adequate spacing and design of access to crossroads in the vicinity of freeway ramps are critical to the safety and traffic operations of both the freeway and the crossroad. The research presented in this report develops a methodology to evaluate the safety impact of different access road spacing standards. The results clearly demonstrate the shortcomings of the AASHTO standards and the benefits of enhancing them. The models developed as part of this research were used to compute the crash rate associated with alternative section spacing. The study demonstrates that the models satisfied the statistical requirements and provide reasonable crash estimates. The results demonstrate an eight-fold decrease in the crash rate when the access road spacing increases from 0 to 300 m. An increase in the minimum spacing from 90 m (300 ft) to 180 m (600 ft) results in a 50 percent reduction in the crash rate. The models were used to develop lookup tables that quantify the impact of access road spacing on the expected number of crashes per unit distance. The tables demonstrate a decrease in the crash rate as the access road spacing increases. An attempt was made to quantify the safety cost of alternative access road spacing using a weighted average crash cost. The weighted average crash cost was computed considering that 0.6, 34.8, and 64.6 percent of the crashes were fatal, injury, and property damage crashes, respectively. These proportions were generated from the field observed data. The cost of each of these crashes was provided by VDOT as $3,760,000, $48,200, and $6,500 for fatal, injury, and property damage crashes, respectively. This provided an average weighted crash cost of $43,533. This average cost was multiplied by the number of crashes per mile to compute the cost associated with different access spacing scenarios. These costs can assist policy makers in quantifying the trade-offs of different access management regulations.
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    Adaptive Traffic Signal Control: Game-Theoretic Decentralized vs. Centralized Perimeter Control
    Elouni, Maha; Abdelghaffar, Hossam M.; Rakha, Hesham A. (MDPI, 2021-01-03)
    This paper compares the operation of a decentralized Nash bargaining traffic signal controller (DNB) to the operation of state-of-the-art adaptive and gating traffic signal control. Perimeter control (gating), based on the network fundamental diagram (NFD), was applied on the borders of a protected urban network (PN) to prevent and/or disperse traffic congestion. The operation of gating control and local adaptive controllers was compared to the operation of the developed DNB traffic signal controller. The controllers were implemented and their performance assessed on a grid network in the INTEGRATION microscopic simulation software. The results show that the DNB controller, although not designed to solve perimeter control problems, successfully prevents congestion from building inside the PN and improves the performance of the entire network. Specifically, the DNB controller outperforms both gating and non-gating controllers, with reductions in the average travel time ranging between 21% and 41%, total delay ranging between 40% and 55%, and emission levels/fuel consumption ranging between 12% and 20%. The results demonstrate statistically significant benefits of using the developed DNB controller over other state-of-the-art centralized and decentralized gating/adaptive traffic signal controllers.
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    Addressing Uncertainties of Performance Modelling with Stochastic Information Packages – Incorporating Uncertainty in Performance and Budget Forecasts
    Kadar, Peter; Martin, Tim; Baran, Michelle; Sen, Ranita (2015-05-19)
    A large volume of data is collected world-wide to feed pavement management systems (PMS). The data is typically condensed to characterize pavement sections or smaller sub-networks by using statistical measures mostly averages. In this process valuable information is lost, thus increasing the likelihood of providing inaccurate or in some cases misleading answers. The pitfalls of using averages can be avoided by utilizing the full data set and treating each data set as an entity or stochastic information packet (SIP). Modeling with SIPs means that the input as well the output of the modeling is a distribution as opposed to the singular outcome of deterministic models. The resulting distribution allows determination of the probability of the outcome besides its predicted value. Budget and condition forecasts therefore may include not only the future condition and budget requirements, but their reliability and consequently the level of associated risks. Managing agencies and contractors may choose the budget scenario best reflecting their level of risk acceptance or tolerance. Modeling with SIPs builds on deterministic models by expanding their outcomes into full distributions. Working with arrays (SIPs) requires using a novel approach that is described and illustrated in the paper.
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    Advancing Pavement Surface Evaluation to Support Engineering and Investment Decisions
    Daleiden, Jerome; Burchett, Thomas; Mergenmeier, Andy (2015-05-01)
    The American Association of State Highway and Transportation Officials (AASHTO's) Pavement Rutting and Cracking Quantification Expert Task Group (ETG) was formed in 2006 with Federal Highway Administration (FHWA) funding to provide program guidance and assistance in development and enhancement of standards for pavement rutting and asphalt pavement surface cracking. The ETG was formed with subject matter experts to represent AASHTO, FHWA, the American Society for Testing and Materials (ASTM) Committee E-17 on Vehicle-Pavement Systems, Transportation Research Board (TRB), the Long Term Pavement Performance (LTPP) Program, academia, and industry. Revised data collection and analysis protocols have been produced and evaluations are being initiated to identify how best to continue the development process.
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    AERIS : Eco-Vehicle Speed Control at Signalized Intersections Using I2V Communication
    Rakha, Hesham A.; Kamalanathsharma, Raj Kishore; Ahn, Kyoungho (United States. Joint Program Office for Intelligent Transportation Systems, 2012-06)
    This report concentrates on a velocity advisory tool, or decision support system, for vehicles approaching an intersection using communication capabilities between the infrastructure and vehicles. The system uses available signal change information, vehicle characteristics, lead vehicle characteristics, and intersection features to compute the fuel-optimal vehicle trajectory. The proposed system involves a complex optimization logic incorporating roadway characteristics, lead vehicle information, vehicle acceleration capabilities and microscopic fuel consumption models to generate a fuel-optimal speed profile. The research also develops a MATLAB application in order to demonstrate the potential of an in-vehicle application of such a technology.
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    AERIS: Eco-driving Application Development and Testing
    Rakha, Hesham A.; Ahn, Kyoungho; Park, Sangjun (United States. Department of Transportation. Research and Innovative Technology Administration, 2012-06)
    This exploratory study investigates the potential of developing an Eco-Driving application that utilizes an eco-cruise control (ECC) system within state-of-the-art car-following models. The research focuses on integrating predictive cruise control and optimal vehicle acceleration and deceleration controllers within car-following models to minimize vehicle fuel consumption levels. This system makes use of topographic information, spacing to lead vehicle, and a desired (or target) vehicle speed and distance headway as input variables.
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    Agent-Based Game Theory Modeling for Driverless Vehicles at Intersections
    Rakha, Hesham A.; Zohdy, Ismail H.; Kamalanathsharma, Raj Kishore (United States. Department of Transportation, 2013-02-19)
    This report presents three research efforts that were published in various journals. The first research effort presents a reactive-driving agent based algorithm for modeling driver left turn gap acceptance behavior at signalized intersections. This model considers the interaction between driver characteristics and vehicle physical capabilities. The model explicitly captures the vehicle constraints on driving behavior using a vehicle dynamics model. In addition, the model uses the driver's input and the psychological deliberation in accepting/rejecting a gap. The model is developed using a total of 301 accepted gaps and subsequently validated using 2,429 rejected gaps at the same site and also validated using 1,485 gap decisions (323 accepted and 1,162 rejected) at another site. The proposed model is considered as a mix between traditional and reactive methods for decision making and consists of three main components: input, data processing and output. The input component uses sensing information, vehicle and driver characteristics to process the data and estimate the critical gap value. Thereafter, the agent decides to either accept or reject the offered gap by comparing to a driver-specific critical gap (the offered gap should be greater than the critical gap for it to be accepted). The results demonstrate that the agent-based model is superior to the standard logistic regression model because it produces consistent performance for accepted and rejected gaps (correct predictions in 90% of the observations) and the model is easily transferable to different sites. The proposed modeling framework can be generalized to capture different vehicle types, roadway configurations, traffic movements, intersection characteristics, and weather effects on driver gap acceptance behavior. The findings of this research effort is considered as an essential stage for modeling autonomous/driverless vehicles The second effort develops a heuristic optimization algorithm for automated vehicles (equipped with cooperative adaptive cruise control CACC systems) at uncontrolled intersections using a game theory framework. The proposed system models the automated vehicles as reactive agents interacting and collaborating with the intersection controller (manager agent) to minimize the total delay. The system is evaluated using a case study considering two different intersection control scenarios: a four-way stop control and the proposed intersection controller framework. In both scenarios, four automated vehicles (a single vehicle per approach) were simulated using a Monte Carlo simulation that was repeated 1000 times. The results show that the proposed system reduces the total delay relative to a traditional stop control by 35 seconds on average, which corresponds to an approximately 70 percent reduction in the total delay. The third effort presents a new tool for optimizing the movements of autonomous/driverless vehicles through intersections: iCACC. The main concept of the proposed tool is to control vehicle trajectories using Cooperative Adaptive Cruise Control (CACC) systems to avoid collisions and minimize intersection delay. Simulations were executed to compare conventional signal control with iCACC considering two measures of effectiveness - delay and fuel consumption. Savings in delay and fuel consumption in the range of 91 and 82 percent relative to conventional signal control were demonstrated, respectively. It is anticipated that the findings of this report may contribute in the future of advanced vehicles control and connected vehicles applications.
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