Browsing by Subject "Skid resistance"

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Developing a framework to quantify the benefit cost ratio of skid resistance intervention thresholds at the network level
(2021-05-20) Galvis Arce, Oscar Daniel; Zhang, Zhanmin, 1962-; Prozzi, Jorge A; Machemehl, Randy B; Gao, Lu
Research has proven that low values of pavement friction increase crash rates. For this reason, highway agencies such as the Federal Highway Administration (FHWA) and the American Association of Highway and Transportation Officials (AASHTO) have provided guidelines for the management of pavement friction, including minimum friction levels recommended for roadway networks. Following these recommendations, some state transportation agencies have established minimum friction thresholds in terms of the Skid Number (SN). Additionally, FHWA lists the Benefit-Cost Ratio (BCR) as one of the methodologies that can assist decision makers in the definition of these thresholds. However, there are limited studies conducted to quantify the BCR when determining the minimum SN threshold for a roadway network. The objective of this study is to fill this research gap by providing a methodology to quantify the BCR when establishing minimum pavement friction thresholds for roadway networks. The first step is to develop models for characterizing the deterioration of skid resistance and predict its future conditions for two scenarios: 1) base scenario where no treatments are applied, and 2) improvement scenario where treatments are applied. Benefits are estimated in terms of the monetary value of crash reductions. Costs are estimated by considering: a) the cost of applying treatments to pavement sections, b) the monetary value of travel time delays associated with work zones, and c) the monetary value of road safety risks associated with work zones. A case study was first developed to assess the accuracy of Markov Chain processes to model skid resistance deterioration. Then, the proposed methodological framework for BCR estimation was applied to a roadway network consisting of 993 highway sections in Texas as a case study to demonstrate its applicability. The case study analysis was performed for three groups of roadways: Interstate Highways, Urban Freeways, and Arterials and Collectors. The research findings indicate that the proposed methodology can provide transportation agencies with an analytical tool to effectively estimate the BCR of maintenance policies intended to establish a minimum SN for a roadway network. Moreover, an analysis was conducted to examine the impact of three alternatives that incorporate SN into the Pavement Management Plan (PMP). The results suggest that there are potential benefits of incorporating SN-related targets into the overall pavement management process.
Implication of Aggregates in the Frictional Performance of Seal Coat Overlays
(International Center for Aggregates Research, 1988) International Center for Aggregates Research
To investigate the effect of aggregate type on pavement friction, researchers used Texas as a test model and constructed 59 seal coat test sections 1,000 feet (304 m) long in the four climatic regions of the state. The environmental characteristics of these four regions included: wet and no freeze; wet and freeze-thaw cycling; dry and no freeze; and dry and freeze-thaw cycling. Researchers used many of the aggregate types that are common to each region, and economically available, in the design mixture for each seal coat section.
Laboratory investigation of diamond grinding and grooving textures on concrete pavement surfaces
(2016-05) Cheruku, Sumanth Reddy; Fowler, David W.; Bhasin, Amit
Polishing of surface texture warrants a rehabilitative treatment that addresses just the surface for safe riding experience. The rate of polishing was found to be proportional to the hardness of the aggregates used in the concrete mixture. The lack of hard aggregates is prompting a surface texture rehabilitation every 2 to 3 years which is neither economical nor sustainable. In this context, the texture generated during diamond grinding operation is believed to be enough to provide the required skid resistance. Diamond grinding is a part of a Concrete Pavement Rehabilitation (CPR) technique that is used primarily to plane the pavement surface. The practice results in a strong macrotexture that is adequate to provide an improvement in the skid resistance of the pavement. This study initiates the process of investigation of the parameters and the effectiveness of diamond grinding in a laboratory setting. It was observed that the configuration of diamond grinding adopted is dependent on the type of aggregate as the exposed coarse aggregate polishing is responsible for the loss of the generated macrotexture. A protocol is developed in which the pavements that are experiencing low skid resistance are selected and subjected to a series of different textures. An optimal configuration is suggested based on the polishing performance of each section with different textures. This laboratory based protocol is quick and can provide the interested agency with an optimal configuration within a short period of time and with reliable accuracy. Most importantly, this practice saves the cost of implementation of different configurations on the pavement section. This study explains the developed protocol and applies it to four sections that have polished surfaces in the Dallas and Fort Worth districts, in the state of Texas. A part of this study also explores the potential of re-grinding a section after the textured surface is polished. An equal performance was observed after re-grinding suggesting that a pavement can be ground multiple times before the need (and budget) for an overlay arises.
Predicting friction with improved texture characterization
(2017-05) Zuniga Garcia, Natalia; Prozzi, Jorge Alberto
Current methodologies to measure road friction present several disadvantages that make them impractical for field data collection over large highway networks. Thus, it is important to study different ways to estimate surface friction characteristics based on other properties that are easier to measure. The main objective of this study was to analyze surface texture characteristics and to observe their influence on friction. A Line Laser Scanner (LLS) was implemented to make an improved characterization of the road texture which includes macro- and micro-texture description using different texture parameters. Field measurements of friction and texture were collected around Texas using different tests methods. The friction characterization tests included the British Pendulum test (BPT), the Dynamic Friction test (DFT), and the Micro GripTester. Thirty-six different pavement sections were evaluated, including different surface types such as hot-mix asphalt (HMA), surface treatment, and concrete sidewalk. Among the principal conclusions, it was found that there is not a unique relationship between texture and friction. The relationship between texture and friction is strong but it is different for each type of surface, thus, cross-sectional analysis cannot be utilized to quantify the relationship. Additionally, the prediction of friction measures obtained using the BPT and the DFT significantly improved when including information of both macro- and micro-texture into the prediction model. Therefore, a measure of micro-texture should be included into friction models based on texture. Finally, among the study of different texture parameters, the mean profile depth (MPD) was the most significant parameter for macro- and for micro-texture to explain the distinct friction measures.
Quantitative relationships between crash risks and pavement skid resistance
(2013-12) Long, Kan; Zhang, Zhanmin, 1962-
Faced with continuously increasing maintenance due to aging infrastructure, the Texas Department of Transportation (TxDOT) is evaluating the potential impact of reduced funding on highway safety. The main objective of this thesis is to develop a methodological procedure to identify threshold levels of pavement skid resistance for highways in the context of traffic crashes, assisting TxDOT Administration and engineers in making proper maintenance decisions. As a result, the efficiency and safety of the highway system could be preserved. The scope of this study covers all types of state-maintained highways in Texas. The primary objectives of this thesis include: 1) synthesis of literature; 2) quantification of the relationship between crash risk and pavement skid resistant; 3) determination of critical skid resistant threshold levels; and, 4) benefit cost analysis. A detailed methodology framework was developed and a comprehensive database was generated from four data files containing pavement, geometry, traffic, and crash information to support this research. The impact of skid resistance level on crash risks was proven to be significant based on the results of regression analysis and insights provided by TxDOT experts. The quantitative relationships between crash risk and skid resistance were quantified using the Crash Rate Ratio method. Hierarchical structure grouping was used to categorize the entire network into homogeneous groups based on traffic level, roadway alignment and other factors. Critical skid resistance threshold levels were determined for the whole state as well as for stratified highway groups. Finally, benefit/cost ratio analyses were conducted to evaluate the effectiveness of pavement maintenance treatments to restore or increase skid resistance.
Use of manufactured sands for concrete paving
(2011-08) Rached, Marc Manuel, 1984-; Fowler, David W.; Juenger, Maria; Bhasin, Amit; Ferron, Raissa; Wheat, Harovel G.
Manufactured fine aggregates are a product created when rocks are crushed using a mechanical crusher. With the depletion of sources of natural sands, the usage of manufactured fine aggregates has increased. Manufactured fine aggregates have properties that differ from natural sands; for this reason, the plastic and hardened properties of concrete produced using manufactured fine aggregates differ from the properties of concrete made with natural sands. The main concrete properties affected by the usage of manufactured fine aggregates are skid resistance, workability, and finishability. The aim of this research project was to investigate how manufactured fine aggregates could be used in concrete pavements without causing workability or skid related issues. To improve the workability of concrete made with manufactured fine aggregates, the use of the optimized mixture proportioning method developed by the International Center for Aggregate Research (ICAR) was investigated. Results obtained from this testing were used to make recommendations on how the ICAR method for pavement concrete could be improved The goal of this research was to also develop laboratory tests that could reasonably predict skid performance of concrete pavements made with different types of sand. For this purpose concrete slabs made with different sands were evaluated for friction and texture using a circular texture meter (CTM), a dynamic friction tester (DFT), and a polisher. To ensure that the values obtained at the laboratory related to field performance, test sections constructed with 100% limestone sand and blended sands were evaluated. Laboratory and field test results for skid were used to identify aggregate tests that best correlates with concrete performance. Results show that the micro-Deval test for fine aggregates could be used to predict the polish resistance of concrete laboratory specimen. Results from field testing has shown that if limestone fine aggregates are not blended with siliceous sands, PCC pavements made with limestone sands on truck lanes could experience a large drop in skid resistance within a year of service. Results obtained from laboratory testing showed that blending a small quantity of siliceous sand with limestone sands considerably increased the skid resistance of concrete specimens.