Gainesville, FL, United States
Gainesville, FL, United States

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Greene J.,Materials Research Park | Toros U.,Applied Research Associates Inc. | Kim S.,University of North Florida | Byron T.,Materials Research Park | Choubane B.,Materials Research Park
Transportation Research Record | Year: 2010

Dual tires have traditionally been used to limit pavement damage by efficiently distributing axle loads over a larger contact area than single tires. However, in recent years, the trucking industry, stating economic and safety benefits, has promoted the use of wide-base single tires. The Super Single tire, an early type of wide-base tire, proved inadequate and induced excessive pavement damage. By contrast, the new generation wide-base tires have contact areas that approach those of dual tires and offer the potential for improved performance. The Florida Department of Transportation investigated the pavement damage potential of four tire types, including a conventional dual tire (11R22.5), a Super Single (425/65R22.5), and two newly designed wide-base single tires (445/50R22.5 and 455/55R22.5 respectively). A controlled accelerated pavement testing program, in addition to theoretical modeling, was performed to determine critical pavement response parameters. Pavement damage was measured in terms of rutting and fatigue cracking (bottom-up or top-down), the predominant distresses in Florida. The investigation revealed that the 455-mm wide-base tire performed as well as the dual tire. By comparison, the 445-mm wide-base tire was shown to create more rut damage on a dense-graded pavement surface and was predicted to create more bottom-up cracking than a dual tire. As expected, the Super Single induced the most damage to the pavement.


Holzschuher C.,Materials Research Park | Choubane B.,Materials Research Park | Lee H.S.,Materials Research Park | Jackson N.M.,University of North Florida
Transportation Research Record | Year: 2010

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 provided by these harmonization efforts is of great practical use in evaluating the frictional characteristics of patterned and textured crosswalks, especially when dealing with constraints such as speed limits. The testing program, the data collection effort, and the subsequent analyses and findings are described, as well as the lessons learned from Florida's experience with patterned and textured pavements.


Holzschuher C.,Materials Research Park | Choubane B.,Materials Research Park | Fletcher J.,University of North Florida | Sevearance J.,University of North Florida | Lee H.S.,Materials Research Park
Transportation Research Record | Year: 2010

The mobile retroreflectometer unit (MRU) has been recognized by highway agencies as an appealing alternative to handheld retroreflectometers because of its improved safety and efficiency. Over the past 4 years, the Florida Department of Transportation has been researching the use of the MRU for evaluating pavement markings continuously and reliably at traffic speeds. Because the stripe surface is nonuniform and the measurement process relies on the operator-driven instrument device, there is some uncertainty in evaluating pavement markings with the MRU. As part of the broader effort for MRU implementation, this research assesses MRU precision in repeatability for pavement marking retroreflectivity. Six designated sections of roadway were selected at random for testing on various pavement surfaces and pavement stripes (paint and thermoplastic). Retroreflectivity data were collected only on the white edge lines of the test sites. The survey limits were selected so that the effect of nonretroreflective-related variables, such as breaks in the pavement markings, inclines, declines, and curves in the roadway, could be minimized. The data were analyzed to determine the pavement marking characteristics at each test location for retroreflectivity at 80 km/h (50 mph) using the reduced 30-m geometry standard. Results indicated that the retroreflectance values from two properly conducted tests using the same MRU on the same pavement marking should not differ by more than 20.1 mcd/m2/lux or 6.7% at a 95% confidence level for retroreflectivity values ranging between 200 and 450 mcd/m 2/lux. This paper presents a description of the testing program, the data collection effort, and the subsequent analyses and findings.


Choubane B.,Materials Research Park | Lee H.,Materials Research Park | Holzschuher C.,Materials Research Park | Upshaw P.,Materials Research Park | Jackson N.,University of North Florida
Transportation Research Record | Year: 2012

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 practical use and provides an alternative to the international friction index for Florida's conditions.


Choubane B.,Materials Research Park | Sevearance J.,University of North Florida | Lee H.S.,Materials Research Park | Upshaw P.,Materials Research Park | Fletcher J.,University of North Florida
Transportation Research Record | Year: 2013

The Florida Department of Transportation has historically used a combination of handheld devices and visual surveys to evaluate the retroreflectivity of pavement markings. However, visual surveys have the inherent limitations of operator bias, while the use of a handheld device is slow and labor intensive and presents safety hazards. Many highway agencies have recognized that a mobile retroreflectivity unit (MRU) may be a safer and more efficient alternative to the handheld retroreflectometers. Because the measurement process relies on the operator-driven instrument, a level of uncertainty is always a concern in evaluating pavement markings with the MRU. This research was aimed at assessing the precision and bias of the MRU while using the handheld retroreflectometer as a reference device. Ten 1.0-mi-long field sites were selected to include various pavement surface types and pavement marking materials (paints and thermoplastics). The results indicated that, when compared with the handheld retroreflectometers, the MRU demonstrated no statistical differences or bias at a 95% confidence level for the retroreflectivity values ranging between 200 and 800 mcd/m2/lux. In addition, it was determined that the retroreflectivity values from two properly conducted tests using a single MRU on the same pavement marking should not differ by more than 7.8%, and when different MRUs were used on the same pavement marking, the retroreflectivity values should not differ by more than 13.3%. This paper presents a description of the testing program, the data collection effort, and the subsequent analyses and findings.


Mraz A.,Applied Research Associates Inc. | Nazef A.,Materials Research Park | Lee H.,Materials Research Park | Holzschuher C.,Materials Research Park | Choubane B.,Materials Research Park
Transportation Research Record | Year: 2012

Traditionally, the Florida Department of Transportation (DOT) has measured faulting with a manual fault meter. However, this method is slow and labor intensive, disrupts traffic, and presents safety hazards. Extracting the fault magnitude from a pavement profile collected with an automated high-speed inertial profiler is a more efficient and cost-effective alternative. Thus, the Florida DOT developed the Florida automated faulting method (FAFM), which detects joints and calculates faulting from longitudinal profile data. A study was conducted to establish the accuracy and precision of the FAFM. In addition, an improved manual fault meter was developed by the Florida DOT and used as a reference device for the FAFM in the field. Because accuracy and precision measures for the new fault meter were not readily available, the study assessed the accuracy of the fault meter under controlled laboratory conditions, as well as the precision in both laboratory and field conditions. The results of the study indicated that the manual fault meter demonstrated no bias and a repeatability of 0.06 mm (0.002 in.) in laboratory conditions. Under field conditions, the fault meter showed a repeatability of 0.42 mm (0.02 in.). Also under field conditions, the FAFM achieved accuracy in terms of bias ranging between 0.2 mm (0.01 in.) and 0.7 mm (0.03 in.). The repeatability and reproducibility of the FAFM were determined to be 0.6 mm and 0.9 mm (0.04 in.), respectively.


Nazef A.,Materials Research Park | Mraz A.,Applied Research Associates Inc. | Choubane B.,Materials Research Park
Transportation Research Record | Year: 2010

Several states have adopted profiler-based systems for automatic measurement of faulting in jointed concrete pavements. However, little published work exists that documents the validation process for these automated faulting systems. An alternative practice for making an initial assessment of a newly developed automated faulting method was documented. Findings from this experiment showed that a high-speed inertial profiler used in conjunction with a faulting reference device provides a practical validation method under controlled conditions. Furthermore, the algorithm that controls the automated faulting measurement method provides reliable and highly repeatable faulting results. The test equipment used in the experiment, as well as the data collection process, the analysis, the subsequent findings and recommendations, are documented.


Amarasiri S.,4020 East Fowler Avenue | Gunaratne M.,4020 East Fowler Avenue | Sarkar S.,4020 East Fowler Avenue | Nazef A.,Materials Research Park
Transportation Research Record | Year: 2010

Evaluation of traffic and environmental impact on pavements using digital images has become increasingly popular in recent years because of the improved efficiency it brings to pavement management. Meanwhile, significant leaps have been made in the sciences of computer vision and image processing. Although automated pavement distress evaluation using digital images has benefitted from the advances in image processing, innovative techniques used in computer vision, such as image characterization using quantification of optical texture properties of images, has not been exploited adequately in pavement evaluation. Several widely used optical texture techniques for characterization of digital images are introduced in this paper, and their useful applications in pavement evaluation are highlighted. Automated and accurate detection of correspondences in progressive images of the same pavement captured during different times is essential for close monitoring of cracks or wear at the project level. Two reliable methods for determining correspondences among pavement images irrespective of the illumination at capture are (a) texture masking and minimum texture distance method, applicable to locations with no significant distress, and (b) homogeneous coordinate geometrical matching and the maximum texture distance to detect the locations of distress. Scaled scattering index, which is a parameter ideal for estimating the size of texture primitives required for texture analysis and characterization of the pavement surface composition, is also introduced. Finally, texture characterization is applied to detection of exact locations of crack propagation and excessive pavement wear.


Greene J.,Materials Research Park | Nazef A.,Materials Research Park | Choubane B.,Materials Research Park
Transportation Research Record | Year: 2011

In 1978, an experimental two-layer concrete pavement was opened to traffic on SR-45 near Fort Myers, Florida. The experimental pavement included a series of two-layer concrete pavement sections with various design features placed over either a granular or a cement-treated subbase. These sections consisted of a 3-in. (7.5-cm) portland cement concrete (PCC) surface over a 9-in. (23-cm) lean concrete (commonly referred to as econocrete) layer. The control section consisted of a standard PCC 9 in. (23 cm) thick with joints spaced at 20 ft (6 m) on a cement-treated subbase. After 30 years of service, the sections constructed over a granular base performed better than those placed over a cement-treated subbase. The distresses on the two-layer concrete pavement sections built on the granular subbase were minimal, regardless of their slab lengths. In contrast, the control section experienced greater cracking, greater corner deflections, and moderate-to-severe spalling. The findings validate several features of Florida's current design policies, such as limiting joint spacing to 15 ft and prohibiting cement-treated subbases directly below concrete pavements. Furthermore, this project has demonstrated that a two-layer concrete system consisting of a relatively thin high-quality PCC surface over a lower-quality econocrete layer and a granular subbase can be a sustainable and long-lasting pavement design alternative.


Greene J.,Materials Research Park | Nazef A.,Materials Research Park | Choubane B.,Materials Research Park | Horhota D.,Materials Research Park
Transportation Research Record | Year: 2014

Many regions throughout Florida have thick deposits of organic soil. Roadways built over these deposits often exhibit differential settlement, significant rut depths, and extensive cracks in a relatively short period of time. The Florida Department of Transportation constructed an experimental project on a realigned portion of State Road 15 on the southeastern shore of Lake Okeechobee in Palm Beach County to evaluate the effect of geosynthetic reinforcement on pavement performance. This roadway traverses farmlands with deep layers of organic material just beneath the surface and has a history of poor performance. The experimental project included four 500-ft sections with combinations of geogrids and geotextiles placed below the base and above the organic material. A fifth section of similar length was constructed with no geosynthetic reinforcement and served as a control. In addition to geosynthetic reinforcement, the alignment was surcharged before construction. The investigation showed that surcharging alone significantly improved the pavement performance compared with historical pavement condition and rehabilitation records. Geosynthetic reinforcement doubled the equivalent single-axle loads allowed on the unreinforced section. A rigid geogrid or woven geotextile placed below the base appeared to provide a slightly stiffer and better-performing pavement than a flexible geogrid. This paper documents the research program and provides details on the improvement resulting from surcharging and geosynthetic reinforcement.

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