Sponsoring Agency Code Supplementary NotesPrepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration. AbstractThis study investigated many important issues associate with pavement surface friction testing, in particular using the smooth tire. This study utilized 3-D FEM program to investigate the fundamental friction phenomenon in light of energy dissipation during friction process. It was demonstrated that the pavement friction depends on many factors such as test tire, test speed, surrounding conditions, pavement surface texture, and pavement type. A great amount of friction data has been collected so as to investigate variations involved in pavement friction measurements. System variations depend on the feature of pavement surface. The standard deviations due to system errors are usually less than 5. The smooth tire tends to provide greater variations than the ribbed tire. As air temperature increases, the friction number does not necessarily decrease. No consistent relations were identified between friction measurements and test seasons. Seasonal friction variations are negligible. The largest directional variation is 16 with the smooth tire on a State road. The State and U.S. roads tend to produce greater directional variations than the interstates. Driving lane usually has lower friction than other lanes. The greatest lateral variation arose due to the effect of wheel track. Longitudinal friction variations depend on traffic distribution, pavement type, and surrounding conditions. Friction measurements taken at 1.0-mile spacing can provide realistic network pavement friction information. Pavement frictions on interstates decreased faster than those on State and US roads. INDOT conducts pavement inventory friction test every year on interstates and every three years on State and US roads.The force transducers should be calibrated every month and the whole system performance verified every week so as to identify potential significant performance changes. A minimum of three to five test runs must be conducted for system verification. The standard smooth tire is recommended for INDOT network pavement inventory friction test. In general, the friction number measured with the ribbed tire is greater than that with the smooth tire. However, the differences decrease as the surface texture becomes rougher. The average friction difference is about 20 on highway pavements. Friction test speed should be determined in light of the traffic conditions. Three test speeds of 30 mph, 40 mph, and 50 mph are recommended for network pavement inventory friction testing. Determination of the minimum friction requirement should consider its impact on wet-pavement accidents and agency's budgets. Taking into account the minimum friction requirement recommended by NCHRP Report-37 and the differences between the ribbed and smooth tires, a friction number of 20 with the smooth tire at 40 mph is recommended as the minimum friction requirement for network pavement inventory friction testing. ...

This page intentionally left blank. Supplementary NotesPrepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration. AbstractThe implementation of a pavement preservation program involves a learning curve with not only a determination to succeed, but also the courage to fail. Also, successful implementation of pavement preservation program requires knowledge of the performance of preservation surface treatments over time, which is critical to the select of candidate projects and the development of performance models for pavement management analysis. In addition, preservation surface treatments, such as chip seal, fog seal, microsurfacing, 4.75 mm thin or ultra-thin overlay, can not only repair certain pavement surface defects, but also change the surface characteristics of pavement and therefore affect pavement surface friction performance. Nevertheless, such information is currently not available but is essential for the Indiana Department of Transportation (INDOT) to evaluate the effectiveness of pavement preservation surface treatments. As a concentrated effort, this study focused on the long-term friction performance of preservation surface treatments, particularly those have been widely used and those have seen increasing use by INDOT.Based on the selected field pavement test sections, this study aimed to evaluate the surface characteristics, particularly the longterm friction performance for those surface treatments that have been widely used and have seen increasing use by INDOT, including chip seal, fog-chip, fog seal, rejuvenating seal, microsurfacing, ultrathin bonded wearing course (UBWC), 4.75-mm hot mix asphalt (HMA) thin overlay, and profile milling (or diamond grinding). The test sections for each type of surface treatment covered a wide range of traffic volume from light to high. The service life for the selected test sections varied from 6 months to 60 months. Friction testing was mainly conducted using ASTM E 274 locked wheel trailer. Surface texture testing was conducted using either the ASTM E 2157 circular track meter (CTM) or a laser scanner. Pavement roughness and noise tests were also conducted to address the smoothness and noise issues, particularly on microsurfacing. Detailed analysis was provided to evaluate the friction performance of 4.75-mm HMA overlays. It is believed that the test results and findings drawn from this study not only provides timely information for INDOT to improve its pavement preservation program, but also provides the original information for the potential readers to better utilize preservation surface treatments. Key WordsPavement preservation, surface friction, macrotexture, mean profile depth, chip seal, fog-chip seal, fog seal, rejuvenating seal, microsurfacing, ultrathin bonded wearing course (UBWC), 4.75-mm hot mix asphalt (HMA) thin overlay (UTO), and profile milling (or diamond grinding). Distribution StatementNo restrictions. This document is available to the public through the National Technical Information S...

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In recent years, state highway agencies have come to understand the need for high quality pavement condition data at both the project and network levels. At the same time, agencies also realize that they have become too dependent on contractors to ensure the quality of the delivered data without any means to independently assure the quality of these delivered data. This research study therefore aims to investigate the inherent variability of the automated data collection processes and proposes guidelines for an automated data collection quality management program in Indiana. In particular, pavement roughness data (in terms of IRI) and pavement surface distress data (in terms of PCR and individual pavement surface distress ratings) are considered in this study. Quality control protocols adopted by the contractor are reviewed and compared against industry standards. A complete quality control plan is recommended to be adopted for all phases of the data collection cycle: preproject phase, data collection phase, and post-processing phase. Quality assurance of pavement condition data can be viewed in terms of (i) completeness of the delivered data for pavement management; (ii) accuracy, precision and reliability of pavement roughness data; and (iii) accuracy, precision and reliability of individual distress ratings and an aggregate pavement condition rating. An innovative two-stage approach is developed in this study to evaluate delivered data for integrity and completeness. Different techniques and performance measures that can be used to evaluate pavement roughness and pavement surface distress data quality are investigated. Causes for loss in IRI and PCR accuracy and precision are identified and statistical models are developed to relate project-and network-level IRIs and PCRs. Quality assurance procedures are then developed to allow highway agencies improve their pavement condition data collection practices and enhance applications in the pavement management systems.

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The contents of this report reflect the views of the author who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Indiana Department of Transportation or the Federal Highway Administration at the time of publication. This report does not constitute a standard, specification, or regulation.

Some researchers have investigated the evaluation of pavement friction using macrotexture measurements and found that the relationship between friction and macrotexture is extremely weak. Textures that affect surface friction include both macrotexture and microtexture. While macrotexture can be readily measured at highway speeds currently, micro-texture is evaluated by the friction from a surrogate device at low speeds. Microtexture depends mainly on the surface properties of the aggregates and plays an important role in developing friction force. The evaluation of pavement friction solely from texture measurements will be undermined without considering microtexture. This paper presents a study conducted to examine the use of laser-based sensors in measuring microtexture. The requirement of frequency was first established for choosing lasers for measuring pavement textures. Three variables, including the mean profile depth the slope variance and the root-mean-square were evaluated and utilized to characterize the microtexture profiles. These three variables varied with the baseline length and produced useful information for evaluating pavement friction. The correlation between surface friction and macrotexture and microtexture was also examined.

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