Developing Implementable Climatic Input Data and Moisture Boundary Conditions for Pavement Analysis and Design

The main objective of this study is to develop a practical and implementable numerical model for predicting the moisture (suction) regime within the pavement subgrade system. The research quality and uniformly-dispersed climate data over short distances from Oklahoma Mesonet and the Mitchell based moisture (suction) prediction methods establish the main background of the research study. The study involved numerical modeling and statistical analysis of climatic weather data. The proposed moisture variation model predicts the suction distribution throughout the soil subgrade by solving the diffusion equation and incorporates the measured suction from the Oklahoma Mesonet to estimate the diffusion coefficient. The research study resulted in a practical prediction model that could be used to determine the moisture boundary conditions within the pavement structure

DEVELOPMENT OF A PROTYPE GEOTECHNICAL REPORT

Archive geotechnical reports in the department contain valuable information such as site maps, photographs, borehole data, laboratory and field test data, and design analyses. A proper use of the information may bring significant cost saving for future projects. Currently, thousands of archive geotechnical reports are stored in paper file boxes in the material division of the department. The current way of file storage makes it very difficult to search and distribute the geotechnical information. The objective of this study is to develop a prototype geotechnical report database to allow easy report archiving and accessing for the department. The research team investigated the practice and recent development of other state DOTs and assessed the efficiency of the current file storage in the material division. The prototype database developed currently allows all computers under ODOT network to search and view about one hundred geotechnical reports in pdf format. The database was developed using Microsoft Access. However, the information in the database can also be accessed from an equivalent KML file using Google Earth, Google Map, ArcGIS desktop, ArcGIS explorer or other compatible programs. With the KML file, users can view all available reports on a map and access the PDF reports by clicking the hyperlink on the map.Final report, October 2013-September 2014N

DEVELOP DRAFT CHIP SEAL COVER AGGREGATE SPECIFICATION BASED ON AGGREGATE IMAGING SYSTEM (AIMS) ANGULARITY, SHAPE, AND TEXTURE TEST RESULTS

The objective of the study is to improve Oklahoma Department of Transportation (ODOT) chip seal design and performance through introducing new criteria for the selection of cover aggregate and binder. The study evaluates the shape and texture-related index properties, as well as durability, of commonly used cover aggregates in chip seal programs in Oklahoma. Additionally, it provides a methodology for inclusion of these characteristics as a metric in future chip seal specifications. The study includes both laboratory testing and construction and performance evaluation of chip seal test sections. The study quantifies how well the newly developed performance-based uniformity coefficient (PUC) correlates with chip seal performance in Oklahoma, and if it should be incorporated into state chip seal specifications. It has generated aggregate-binder compatibility data, based on the surface free energy (compatibility ratio) approach, for commonly used aggregates and asphalt emulsion binders in Oklahoma. Moreover, the chip seal construction practice followed by different ODOT Maintenance Divisions was documented and the best practice identified. This repository of information will be a useful resource for ODOT maintenance divisions.Final report, October 2011-December 2013N

DRYING SHRINKAGE PROBLEMS IN HIGH PI SUBGRADE SOILS

The main objective of this study was to investigate the longitudinal cracking in pavements due to drying shrinkage of high PI subgrade soils. The study involved laboartory soil testing and modeling. The shrinkage cracks usually occur within the vicinity of the edge of the pavement where moisture boundary conditions play a significant role in the behavior of expansive subgrade soils. The study investigated the shrinkage problems in pavement subgrade soils at four sites in Oklahoma. The soil specimens collected from the sites were tested for the basic index properties as well as soil suction and unsaturated diffusivity measurements. Various ranges of the test results have been implemented in suction profile and tensile stress prediction models for evaluating the typical suction changes and the corresponding tensile stresses in subgrade soils.Final report, October 2011-December 2013N

EVALUATION OF THE ENHANCED INTEGRATED CLIMATIC MODEL FOR SPECIFICATION OF SUBGRADE SOILS IN OKLAHOMA

The main objective of this study was to collect and evaluate climatic and soil data pertaining to Oklahoma for the climatic model (EICM) in the mechanistic-empirical design guide for pavements. The EICM climatic input files were updated and extended over a large area covering Oklahoma climatic conditions. Large cluster of raw climate and soil moisture data were obtained from the Oklahoma Mesonet for evaluation and use in creating the necessary input parameters for the climatic model. Historical climatic data were also employed for classifying climatic regions in Oklahoma using cluster analysis. Thornthwaite Moisture Index (TMI) contour maps were created using the climatic data and ArcGIS software. A comprehensive validation study was also undertaken in comparing the moisture migration processes in the EICM and commercially available software using the climatic and soil data in Oklahoma.Final report, October 2011-December 2013N

Safety of Vulnerable Road Users (VRU\u27s) in Light-Rail Transit (LRT) Environment

Light-rail transit (LRT), which includes modern streetcars, trolleys, and heritage trolleys, is one of the fastest growing modes of public transportation in the United States. To reduce the cost and complexity of construction, most LRT systems have their tracks placed on city streets, in medians, or in separate at-grade rights-of-way with at-grade crossings. Operating light-rail vehicles (LRVs) along these alignments introduces new conflicts and increases the risk of collisions with vulnerable road users (VRUs) including pedestrians, bicyclists, and electric scooter riders. This study has two main objectives: (1) to review and evaluate the existing body of knowledge and the state of practice regarding safety of VRUs in LRT environments; and (2) to synthesize this information and package the results in a “Best Practices Resource Guide” and a companion “PowerPoint Presentation” for use in improving the safety of VRUs in existing LRT systems and advancing the professional capacity of transit workforce. Metropolitan Planning Organizations and State DOTs should also benefit from this resource information in the planning and design of new LRT systems. This report presents a wide range of physical, educational, and enforcement treatments for improving the safety of VRUs in LRT environments. The selection of a particular treatment for use at an LRT grade crossing or station should be based on an engineering study whose scope and complexity depend on local conditions. Factors that should be considered during device selection include 1) pedestrian‐LRV collision experience, 2) pedestrian volumes and peak flow rates, 3) train speeds, frequency of trains, number of tracks, and railroad traffic patterns, 4) sight distances available to pedestrians and LRV operators approaching the crossing, and 5) skew angle, if any, of the crossing relative to the LRT tracks