The Experts below are selected from a list of 837 Experts worldwide ranked by ideXlab platform
Charles Holzschuher - One of the best experts on this subject based on the ideXlab platform.
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Harmonization of Texture and Friction Measurements on Florida's Open-Graded and Dense-Graded Pavements:
Transportation Research Record, 2012Co-Authors: Bouzid Choubane, Charles Holzschuher, Hyung Suk Lee, Patrick Upshaw, N Mike JacksonAbstract:A study was initiated to harmonize the dynamic friction tester and a Locked-Wheel tester on Florida's typical open-graded and dense-graded surfaces under various speed conditions. In addition, two texture measuring devices, the circular track meter and a high-speed 64-kHz laser mounted to the Locked-Wheel tester, were evaluated. These devices were first harmonized at a standard test speed of 40 mph (65 km/h). Because of the increased level of macrotexture in the open-graded mixtures, the open- and dense-graded surfaces were assumed to show different frictional behavior under different speed conditions. As a consequence, the harmonization equations for the open- and dense-graded surfaces were developed separately. Harmonization of different test speeds was also performed for each given test method to allow for converting the friction measured at a range of speeds—30 mph (50 km/h) to 60 mph (95 km/h)—back to that of the standard speed. The flexibility provided by these harmonization efforts is of great prac...
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Measuring Friction of Patterned and Textured Pavements: A Comparative Study
Transportation Research Record, 2010Co-Authors: Charles Holzschuher, Bouzid Choubane, Hyung Suk Lee, N Mike JacksonAbstract:The Florida Department of Transportation initiated a field study to compare the suitability of two friction-testing devices for measuring the friction characteristics of patterned and textured crosswalks: (a) a site-specific dynamic friction tester (DFT) and (b) a semicontinuous Locked Wheel tester. The Locked Wheel testing was performed with both ribbed and smooth tires at 20, 30, and 40 mph (30, 50 and 65 km/h), respectively. Ten test sections were randomly selected to include the different types of patterned and textured processes currently approved for use in Florida. The results of this study indicated that the smooth tire measurements were, generally, in good agreement with the DFT, regardless of test speed. The correlation between the DFT and the ribbed tire test improved with the increasing speed of the Locked Wheel testing. In addition, for a given test method, harmonization of different test speeds was also performed to allow for the speed conversion of the friction coefficients. The flexibility...
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Practical Approach to Measuring and Reporting Friction and Macrotexture at Variable Test Speeds
Transportation Research Record, 2009Co-Authors: N Mike Jackson, Bouzid Choubane, Charles HolzschuherAbstract:Because of safety concerns associated with friction testing on both high-and low-speed facilities, testing at variable speeds has been investigated by the Florida Department of Transportation (DOT) and others. Previous research has demonstrated that reasonable correlations may be developed between friction test data obtained at the standard test speed of 40 mph (64.4 km/h) and other speeds. As part of an effort to harmonize its fleet of full-scale, Locked-Wheel friction testing equipment with portable reference test equipment (ASTM E 1960), the Florida DOT also evaluated the skid number speed gradient (Gv) for use in transforming friction and macrotexture measurements obtained at variable highway speeds. This paper documents the results of this evaluation. On the basis of the results of this study, a practical method of measuring pavement friction and macrotexture at variable highway speeds with the Florida DOT Locked-Wheel test unit and the ribbed tire is presented. Since the results of the ribbed tire t...
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Precision of Smooth and Ribbed Tire Locked Wheel Testers for Measurement of Roadway Surface Friction Characteristics
Transportation Research Record: Journal of the Transportation Research Board, 2006Co-Authors: Bouzid Choubane, Charles Holzschuher, Salil Gokhale, Jim FletcherAbstract:The present state-of-the-art Locked Wheel testers for roadway surface friction evaluation are fully automated. As with any testing using subjectdriven instrumented devices, the major concerns of the end usefulness of the resulting data are accuracy and precision. Although a level of uncertainty is always inherent in any measurement process, it also must be appropriately quantified or assessed. Therefore, the Florida Department of Transportation (FDOT) initiated a field study to assess the level of precision of its own Locked Wheel testers for field measurements. Friction measurements were acquired with four friction Locked Wheel testers concurrently on a number of asphalt section sites. These test sections were randomly selected to include both open and dense-graded surface mixtures. The collected friction data were first analyzed to determine the friction characteristics at each test location in terms of a friction number at 40 mph with a standard ribbed (FN40R) and smooth tire (FN40S). The results were ...
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Precision of Locked-Wheel Testers for Measurement of Roadway Surface Friction Characteristics
Transportation Research Record, 2004Co-Authors: Bouzid Choubane, Charles Holzschuher, Salil GokhaleAbstract:The present state-of-the-art Locked-Wheel testers for roadway surface friction evaluation are fully automated. As with any testing using subjectdriven instrumented devices, the major concerns of the end usefulness of the resulting data are accuracy and precision. Although a level of uncertainty is always inherent in any measurement process, it must also be appropriately quantified or assessed. Therefore, the Florida Department of Transportation (FDOT) initiated a field study to assess the level of precision of its own Locked-Wheel testers for field measurements. Friction measurements were acquired by using four friction Locked-Wheel testers concurrently on a number of asphalt section sites. These test sections were randomly selected to include both open- and dense-graded surface mixtures. The collected friction data were first analyzed to determine the friction characteristics at each test location, in terms of a friction number at 40 mph with a standard ribbed test tire (FN40R). The results were then use...
Bouzid Choubane - One of the best experts on this subject based on the ideXlab platform.
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Harmonization of Texture and Friction Measurements on Florida's Open-Graded and Dense-Graded Pavements:
Transportation Research Record, 2012Co-Authors: Bouzid Choubane, Charles Holzschuher, Hyung Suk Lee, Patrick Upshaw, N Mike JacksonAbstract:A study was initiated to harmonize the dynamic friction tester and a Locked-Wheel tester on Florida's typical open-graded and dense-graded surfaces under various speed conditions. In addition, two texture measuring devices, the circular track meter and a high-speed 64-kHz laser mounted to the Locked-Wheel tester, were evaluated. These devices were first harmonized at a standard test speed of 40 mph (65 km/h). Because of the increased level of macrotexture in the open-graded mixtures, the open- and dense-graded surfaces were assumed to show different frictional behavior under different speed conditions. As a consequence, the harmonization equations for the open- and dense-graded surfaces were developed separately. Harmonization of different test speeds was also performed for each given test method to allow for converting the friction measured at a range of speeds—30 mph (50 km/h) to 60 mph (95 km/h)—back to that of the standard speed. The flexibility provided by these harmonization efforts is of great prac...
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Measuring Friction of Patterned and Textured Pavements: A Comparative Study
Transportation Research Record, 2010Co-Authors: Charles Holzschuher, Bouzid Choubane, Hyung Suk Lee, N Mike JacksonAbstract:The Florida Department of Transportation initiated a field study to compare the suitability of two friction-testing devices for measuring the friction characteristics of patterned and textured crosswalks: (a) a site-specific dynamic friction tester (DFT) and (b) a semicontinuous Locked Wheel tester. The Locked Wheel testing was performed with both ribbed and smooth tires at 20, 30, and 40 mph (30, 50 and 65 km/h), respectively. Ten test sections were randomly selected to include the different types of patterned and textured processes currently approved for use in Florida. The results of this study indicated that the smooth tire measurements were, generally, in good agreement with the DFT, regardless of test speed. The correlation between the DFT and the ribbed tire test improved with the increasing speed of the Locked Wheel testing. In addition, for a given test method, harmonization of different test speeds was also performed to allow for the speed conversion of the friction coefficients. The flexibility...
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Practical Approach to Measuring and Reporting Friction and Macrotexture at Variable Test Speeds
Transportation Research Record, 2009Co-Authors: N Mike Jackson, Bouzid Choubane, Charles HolzschuherAbstract:Because of safety concerns associated with friction testing on both high-and low-speed facilities, testing at variable speeds has been investigated by the Florida Department of Transportation (DOT) and others. Previous research has demonstrated that reasonable correlations may be developed between friction test data obtained at the standard test speed of 40 mph (64.4 km/h) and other speeds. As part of an effort to harmonize its fleet of full-scale, Locked-Wheel friction testing equipment with portable reference test equipment (ASTM E 1960), the Florida DOT also evaluated the skid number speed gradient (Gv) for use in transforming friction and macrotexture measurements obtained at variable highway speeds. This paper documents the results of this evaluation. On the basis of the results of this study, a practical method of measuring pavement friction and macrotexture at variable highway speeds with the Florida DOT Locked-Wheel test unit and the ribbed tire is presented. Since the results of the ribbed tire t...
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Precision of Smooth and Ribbed Tire Locked Wheel Testers for Measurement of Roadway Surface Friction Characteristics
Transportation Research Record: Journal of the Transportation Research Board, 2006Co-Authors: Bouzid Choubane, Charles Holzschuher, Salil Gokhale, Jim FletcherAbstract:The present state-of-the-art Locked Wheel testers for roadway surface friction evaluation are fully automated. As with any testing using subjectdriven instrumented devices, the major concerns of the end usefulness of the resulting data are accuracy and precision. Although a level of uncertainty is always inherent in any measurement process, it also must be appropriately quantified or assessed. Therefore, the Florida Department of Transportation (FDOT) initiated a field study to assess the level of precision of its own Locked Wheel testers for field measurements. Friction measurements were acquired with four friction Locked Wheel testers concurrently on a number of asphalt section sites. These test sections were randomly selected to include both open and dense-graded surface mixtures. The collected friction data were first analyzed to determine the friction characteristics at each test location in terms of a friction number at 40 mph with a standard ribbed (FN40R) and smooth tire (FN40S). The results were ...
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Precision of Locked-Wheel Testers for Measurement of Roadway Surface Friction Characteristics
Transportation Research Record, 2004Co-Authors: Bouzid Choubane, Charles Holzschuher, Salil GokhaleAbstract:The present state-of-the-art Locked-Wheel testers for roadway surface friction evaluation are fully automated. As with any testing using subjectdriven instrumented devices, the major concerns of the end usefulness of the resulting data are accuracy and precision. Although a level of uncertainty is always inherent in any measurement process, it must also be appropriately quantified or assessed. Therefore, the Florida Department of Transportation (FDOT) initiated a field study to assess the level of precision of its own Locked-Wheel testers for field measurements. Friction measurements were acquired by using four friction Locked-Wheel testers concurrently on a number of asphalt section sites. These test sections were randomly selected to include both open- and dense-graded surface mixtures. The collected friction data were first analyzed to determine the friction characteristics at each test location, in terms of a friction number at 40 mph with a standard ribbed test tire (FN40R). The results were then use...
Marilyn E. Carroll - One of the best experts on this subject based on the ideXlab platform.
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Effects of voluntary exercise and sex on multiply-triggered heroin reinstatement in male and female rats.
Psychopharmacology, 2019Co-Authors: J. R. Smethells, A. Greer, B. Dougen, Marilyn E. CarrollAbstract:The rise in heroin addiction has heightened the need for novel and effective treatments. Physical exercise has been shown as an effective treatment for stimulant abuse in clinical and pre-clinical research. However, this treatment has not yet been tested on opioid addiction. This study examined the effects of physical activity (Wheel running) on heroin-seeking in rats within a reinstatement paradigm (i.e., heroin relapse model). Female and male rats were trained to self-administer intravenous heroin (0.015 mg/kg). Once trained, rats were placed into extinction (i.e., heroin abstinence) for 21 days with continuous access to a Locked or unLocked running Wheel. After extinction, rats were tested for drug- (heroin, caffeine, and yohimbine) and cue-primed reinstatement of heroin-seeking. Females completed more Wheel revolutions than males across all study phases. Access to an unLocked running Wheel reduced extinction and reinstatement of heroin-seeking, with greater reductions in females than males across several reinstatement conditions. In the Locked Wheel group, female rats showed greater reinstatement of heroin-seeking than males across several priming conditions. Wheel running reduced heroin-seeking in male and female rats, with females showing a more robust effect during reinstatement. The Locked Wheel group allowed an examination of sex differences in heroin reinstatement, which revealed that females showed greater vulnerability to heroin reinstatement than males, but with no other sex differences observed in maintenance or extinction. Overall, the results indicate that voluntary physical exercise may be an effective treatment for heroin dependence in humans.
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Effects of Wheel Running on Incubation of Cocaine Seeking in Rats
2016Co-Authors: Heather L. Veglahn, Natalie E. Zlebnik, Marilyn E. Carroll, Cole Batty, Clare Chamberlain, Arit HarvankoAbstract:Drug abuse relapse is a major issue in treating addictions. Physical activity decreases cocaine self-administration in lab rats.1 Access to a Wheel has been shown to significantly reduce cocaine-seeking behaviors in female rats, but not in male rats.2 In humans, exercise has been shown to decrease drug craving3 and reduce the probability of relapse4. Objective To assess the effects of chronic Wheel running on the incubation of cocaine-seeking behavior in female rats after extended forced abstinence from cocaine self-administration. 10 days self-administration in operant chamber Moved to Wheel cage and separated into groups 3 Days Locked Wheel 3 Days unLocked Wheel 30 days Locked Wheel 30 days unLocked whee
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Reduction of extinction and reinstatement of cocaine seeking by Wheel running in female rats
Psychopharmacology, 2010Co-Authors: Natalie E. Zlebnik, Justin J. Anker, Luke A. Gliddon, Marilyn E. CarrollAbstract:Rationale and objectives Previous work has shown that Wheel running reduced the maintenance of cocaine self-administration in rats. In the present study, the effect of Wheel running on extinction and reinstatement of cocaine seeking was examined. Female rats were trained to run in a Wheel during 6-h sessions, and they were then catheterized and placed in an operant conditioning chamber where they did not have access to the Wheel but were allowed to self-administer iv cocaine. Subsequently, rats were divided into four groups and were tested on the extinction and reinstatement of cocaine seeking while they had varying access to a Wheel in an adjoining compartment. The four groups were assigned to the following Wheel access conditions: (1) Wheel running during extinction and reinstatement (WER), (2) Wheel running during extinction and a Locked Wheel during reinstatement (WE), (3) Locked Wheel during extinction and Wheel running during reinstatement (WR), and (4) Locked Wheel during extinction and reinstatement (WL). WE and WR were retested later to examine the effect of one session of Wheel access on cocaine-primed reinstatement. Results There were no group differences in Wheel revolutions, in rate of acquisition of cocaine self-administration, or in responding during maintenance when there was no Wheel access. However, during extinction, WE and WER responded less than WR and WL. WR and WER had lower cocaine-primed reinstatement than WE and WL. One session of Wheel exposure in WE also suppressed cocaine-primed reinstatement. Conclusions Wheel running immediately and effectively reduced cocaine-seeking behavior, but concurrent access to running was necessary. Thus, exercise is a useful and self-sustaining intervention to reduce cocaine-seeking behavior.
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Reduction of extinction and reinstatement of cocaine seeking by Wheel running in female rats
Psychopharmacology, 2010Co-Authors: Natalie E. Zlebnik, Justin J. Anker, Luke A. Gliddon, Marilyn E. CarrollAbstract:Rationale and objectives Previous work has shown that Wheel running reduced the maintenance of cocaine self-administration in rats. In the present study, the effect of Wheel running on extinction and reinstatement of cocaine seeking was examined. Female rats were trained to run in a Wheel during 6-h sessions, and they were then catheterized and placed in an operant conditioning chamber where they did not have access to the Wheel but were allowed to self-administer iv cocaine. Subsequently, rats were divided into four groups and were tested on the extinction and reinstatement of cocaine seeking while they had varying access to a Wheel in an adjoining compartment. The four groups were assigned to the following Wheel access conditions: (1) Wheel running during extinction and reinstatement (WER), (2) Wheel running during extinction and a Locked Wheel during reinstatement (WE), (3) Locked Wheel during extinction and Wheel running during reinstatement (WR), and (4) Locked Wheel during extinction and reinstatement (WL). WE and WR were retested later to examine the effect of one session of Wheel access on cocaine-primed reinstatement.
N Mike Jackson - One of the best experts on this subject based on the ideXlab platform.
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Harmonization of Texture and Friction Measurements on Florida's Open-Graded and Dense-Graded Pavements:
Transportation Research Record, 2012Co-Authors: Bouzid Choubane, Charles Holzschuher, Hyung Suk Lee, Patrick Upshaw, N Mike JacksonAbstract:A study was initiated to harmonize the dynamic friction tester and a Locked-Wheel tester on Florida's typical open-graded and dense-graded surfaces under various speed conditions. In addition, two texture measuring devices, the circular track meter and a high-speed 64-kHz laser mounted to the Locked-Wheel tester, were evaluated. These devices were first harmonized at a standard test speed of 40 mph (65 km/h). Because of the increased level of macrotexture in the open-graded mixtures, the open- and dense-graded surfaces were assumed to show different frictional behavior under different speed conditions. As a consequence, the harmonization equations for the open- and dense-graded surfaces were developed separately. Harmonization of different test speeds was also performed for each given test method to allow for converting the friction measured at a range of speeds—30 mph (50 km/h) to 60 mph (95 km/h)—back to that of the standard speed. The flexibility provided by these harmonization efforts is of great prac...
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Measuring Friction of Patterned and Textured Pavements: A Comparative Study
Transportation Research Record, 2010Co-Authors: Charles Holzschuher, Bouzid Choubane, Hyung Suk Lee, N Mike JacksonAbstract:The Florida Department of Transportation initiated a field study to compare the suitability of two friction-testing devices for measuring the friction characteristics of patterned and textured crosswalks: (a) a site-specific dynamic friction tester (DFT) and (b) a semicontinuous Locked Wheel tester. The Locked Wheel testing was performed with both ribbed and smooth tires at 20, 30, and 40 mph (30, 50 and 65 km/h), respectively. Ten test sections were randomly selected to include the different types of patterned and textured processes currently approved for use in Florida. The results of this study indicated that the smooth tire measurements were, generally, in good agreement with the DFT, regardless of test speed. The correlation between the DFT and the ribbed tire test improved with the increasing speed of the Locked Wheel testing. In addition, for a given test method, harmonization of different test speeds was also performed to allow for the speed conversion of the friction coefficients. The flexibility...
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Practical Approach to Measuring and Reporting Friction and Macrotexture at Variable Test Speeds
Transportation Research Record, 2009Co-Authors: N Mike Jackson, Bouzid Choubane, Charles HolzschuherAbstract:Because of safety concerns associated with friction testing on both high-and low-speed facilities, testing at variable speeds has been investigated by the Florida Department of Transportation (DOT) and others. Previous research has demonstrated that reasonable correlations may be developed between friction test data obtained at the standard test speed of 40 mph (64.4 km/h) and other speeds. As part of an effort to harmonize its fleet of full-scale, Locked-Wheel friction testing equipment with portable reference test equipment (ASTM E 1960), the Florida DOT also evaluated the skid number speed gradient (Gv) for use in transforming friction and macrotexture measurements obtained at variable highway speeds. This paper documents the results of this evaluation. On the basis of the results of this study, a practical method of measuring pavement friction and macrotexture at variable highway speeds with the Florida DOT Locked-Wheel test unit and the ribbed tire is presented. Since the results of the ribbed tire t...
Edgar De León Izeppi - One of the best experts on this subject based on the ideXlab platform.
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Interconversion of Locked-Wheel and Continuous Friction Measurement Equipment (CFME) Friction Measurements:
Transportation Research Record: Journal of the Transportation Research Board, 2018Co-Authors: Silvia Barrantes Quiros, Gerardo W Flintsch, Edgar De León Izeppi, Kevin K McgheeAbstract:As transportation agencies are adopting proactive pavement friction management using continuous friction measurement equipment (CFME), the need for a method that allows interconversion between the ...
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Evaluation of the Use of Ribbed Tires for the Characterization of Skid Resistance Using Friction Models
Journal of Testing and Evaluation, 2014Co-Authors: Luis Fuentes, Gerardo W Flintsch, Edgar De León IzeppiAbstract:This paper presents an evaluation of the use of ribbed tires for the characterization of skid resistance using friction models. The data used in this investigation were collected at the Surface Properties Rodeo, which was conducted on the Virginia Smart Road by members of the Virginia Consortium for Pavement Surface Properties. The paper compares measurements obtained using Locked Wheel testers with ribbed and smooth tires on 24 pavement sections covering a wide range of textures. Results confirmed that the International Friction Index (IFI) model is not appropriate for skid data obtained using a Locked Wheel tester with ribbed tires, especially when the pavement surface presents low levels of macrotexture. It was found that the friction measurements obtained when using a Locked Wheel tester with ribbed and smooth tires resulted in different friction–speed curves for the same pavement surface, contrary to the stated ASTM assumption that the friction–speed curve depends only on the characteristics (macrotexture) of the pavement surface. Skid measurements obtained at different speeds using ribbed tires were insensitive to pavement macrotexture. This supports the benefits of using smooth tires, which are sensitive to the drainage capacity of pavement surfaces. Finally, it is recommended that the use of the IFI model on skid data obtained using testers with ribbed tires be reassessed.
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Data Processing and Analysis Software for Continuous Friction Measurement Equipment
Transportation Research Record, 2011Co-Authors: Edgar De León Izeppi, Gerardo W Flintsch, Adrian Ricardo Archilla, Wendy SequeiraAbstract:A major advantage of fixed-slip devices over Locked-Wheel testers is that fixed-slip devices collect friction data continuously at highway speeds with low water consumption and thus make fixed-slip devices a practical choice for collection of network-level pavement friction data. These devices are highly maneuverable and especially adapted for investigating accident sites, supporting wet-weather accident reduction programs, and identifying localized areas with reduced friction. These devices have not been implemented for use on highways in the United States to an extent commensurate with their potential benefits. But the decision to implement this type of equipment will also be influenced by how easy it is to gather and present the information it collects. Although it is inarguable that the quality of a continuous friction profile provides a wealth of information not achievable with most Locked-Wheel testers, the processing of vast amounts of information can be overwhelming for an operator or an analyst r...
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Continuous Friction Measurement Equipment (CFME) Loan Program
2011Co-Authors: Edgar De León Izeppi, Gerardo W FlintschAbstract:Currently, in the United States, highway agencies commonly use Locked-Wheel testers to perform project and network level pavement evaluation. Fixed and variable slip friction measurement devices collect data continuously, so they are also known as a Continuous Friction Measurement Equipment (CFME). This is a big advantage over the Locked-Wheel devices because it offers a practical alternative for network-level pavement friction data collection at highway speeds, and because it can carry out substantial friction surveys with low water consumption. They are also highly maneuverable and especially adapted for investigating accident sites, supporting wet- weather accident reduction programs and identifying localized areas with reduced friction. The Federal Highway Administration (FHWA) has developed a CFME Loan Program to allow state agencies, practitioners and/or researchers the opportunity to evaluate several types of fixed slip CFME devices without the significant financial commitment this would otherwise represent. The program is managed by the Pavement Surface Characteristics Consortium, which is a joint effort between FHWA and six Departments of Transportation (DOTs) and run by the Center for Sustainable Transportation Infrastructure (CSTI) at the Virginia Tech Transportation Institute (VTTI). This paper presents some of the experiences and results that the CFME Loan Program has achieved, especially the software program developed to allow users to view and analyze continuous pavement friction data automatically without further processing. Results from some measurements made at the Smart Road are presented.
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Speed Adjustment Factors for Locked-Wheel Skid Trailer Measurements
Transportation Research Record, 2010Co-Authors: Gerardo W Flintsch, Edgar De León Izeppi, Kevin K Mcghee, Shahriar NajafiAbstract:Locked-Wheel trailers are the predominant friction-testing tool used by state departments of transportation in the United States. These trailers measure friction on a Locked Wheel on the wetted pavement surface as the Wheel slides at a constant speed. The skid resistance is reported as the skid number (SN) at the speed it was measured, with the standard test speed at 40 mph. Speed on most rural interstate and primary roads is rarely lower than 65 mph, whereas in most urban environments, congestion, intersections, and high-traffic volumes can lead to average traffic speeds as low as 20 mph. A methodology was proposed to convert the skid numbers from one speed to any desired speed by using adjustment factors. The data used to develop this methodology came from measurements taken by members of the Pavement Surface Properties Consortium for the three consecutive years from 2007 to 2009. The adjustment factors were developed for the different flexible and continuously reinforced concrete pavement surfaces that are available at the Virginia Smart Road. The friction measurements performed with the skid testers presented different responses to the different pavement surface types. To separate them, principal component analysis was used, and three different groups of surfaces were identified. Principal component analysis was also used to develop a friction conversion method that used correlations between speed and texture. Correlations between speed factors and macrotexture were computed only for smooth tire skid testers, because ribbed tires do not exhibit good relationships, probably because measurements with this tire are not sensitive to macrotexture.
