Department Of Transportation Agencies Research Articles

Developing specifications for precast concrete highway pavements

ABSTRACT Precast Concrete Pavements (PCP) can be used as an accelerated rehabilitation technique for concrete pavements. The goals of this research study was to develop a PCP system approval process for potential implementation by state Departments of Transportation (DOTs) using current PCP specifications and practices. For this, a survey was conducted among 18 states regarding their specifications that are used for PCP and their approval processes for implementation of PCP. Based on the survey conducted, eight state specifications have been developed for PCP. Each specification focuses on four major PCP components: (i) dimensional and strength requirements, (ii) base stabilization materials, (iii) panel placement and alignment, and (iv) encasement grout materials. Based on the specifications and recommendations of state DOTs, a general approval process was developed for PCP systems. The generalized approval process included verification of PCP (i) material properties and precast plant capabilities and (ii) historical performance. The approval process outlines three different tracks in which the PCP contractor can describe past performance (ranging from low to high risk for state DOTs). Overall, this study provides state DOT agencies the necessary specifications and general approval process to improve and accept PCP systems as a pavement rehabilitation technique.

Analytical Comparison of Core Competencies across Civil Engineering Positions within New England Department of Transportation Agencies

As many within the current transportation workforce approach retirement and the industry transitions into the 21st century, there are two notable challenges: 1) the incredible wealth of institutional knowledge that will be leaving the workforce, and 2) the continued increase in the application of new technologies, skills, and knowledge of the entering workforce. A resulting impact of these issues is that the gap between old and new employee competencies and skills is widening; therefore, there is a specific need and opportunity to develop new job competencies which address these changes. This research evaluates existing Department of Transportation (DOT) job specifications and job postings for civil engineers at various levels in the transportation industry within the New England region. Each job specification and posting was gathered and reviewed for specific competencies in accordance with the Bureau of Labor Statistics (BLS) core competencies and the American Association of Engineering Societies’ (AAES) competency model. Further, licensure requirements, including the Engineer-In-Training (EIT) and Professional Engineer (PE) certifications, were gathered. The quantitative analysis resulted in several notable competency gaps (or inconsistencies) between job positions across the DOTs, as well as gaps in both the BLS and AAES competency models. Additionally, the analysis of job position licensure requirements presented further significant gaps between the DOT agencies. This research provides a foundation from which to develop competencies for civil engineering positions at state DOTs and other agencies, one that is reflective of a more dynamic and sustainable transportation workforce that will excel throughout the 21st century.

Field methods for rapidly characterizing paint waste during bridge rehabilitation

For Department of Transportation (DOT) agencies, bridge rehabilitation involving paint removal results in waste that is often managed as hazardous. Hence, an approach that provides field characterization of the waste classification would be beneficial. In this study, an analysis of variables critical to the leaching process was conducted to develop a predictive tool for waste classification. This approach first involved identifying mechanistic processes that control leaching. Because steel grit is used to remove paint, elevated iron concentrations remain in the paint waste. As such, iron oxide coatings provide an important surface for metal adsorption. The diffuse layer model was invoked (logKMe=4.65 for Pb and logKMe=2.11 for Cr), where 90% of the data were captured within the 95% confidence level. Based on an understanding of mechanistic processes along with principal component analysis (PCA) of data obtained from field-portable X-ray fluorescence (FP-XRF), statistically-based models for leaching from paint waste were developed. Modeling resulted in 96% of the data falling within the 95% confidence level for Pb (R2 0.6–0.9, p⩽0.04), Ba (R2 0.5–0.7, p⩽0.1), and Zn (R2 0.6–0.7, p⩽0.08). However, the regression model obtained for Cr leaching was not significant (R2 0.3–0.5, p⩽0.75). The results of this work may assist DOT agencies with applying a predictive tool in the field that addresses the mobility of trace metals as well as disposal and management of paint waste during bridge rehabilitation.

Guide on the Selection of Appropriate Laboratory Stress Levels for the Flow Number Test

This study examines the use of the triaxial shear strength parameters (c and φ) in providing guidelines for selecting the appropriate laboratory stress level for the flow number test of asphalt mixtures. The approach is based on the concept that the flow number (tertiary flow) is inversely related to the applied stress-to-strength ratio of the material. The correlation of the flow number with the stress-to-strength ratio can provide a good estimate of the stress level that will yield tertiary flow within a reasonable testing time. It was also realized that the triaxial shear strength test is not routinely conducted by Department of Transportation agencies and testing laboratories. Therefore, a database of triaxial shear strength test data was used to develop predictive models of the shear strength parameters for a particular asphalt mixture. The models’ predictor variables were based on the volumetric properties of 46 different asphalt mixtures and a total of 276 test results. Regression models to estimate the c and friction (φ) parameters had good statistical measures of model accuracy. The models were used to develop guidelines for laboratory stress-to-strength ratios to achieve tertiary flow within a reasonable testing period.

Sleep Apnea and Commercial Motor Vehicle Operators:

Obstructive sleep apnea (OSA) has been demonstrated to significantly increase safety and health risks. Medical research has shown that OSA is a significant cause of motor vehicle crashes (resulting in a two- to sevenfold increased risk) and increases the possibility of an individual developing significant health problems such as hypertension, stroke, ischemic heart disease, and mood disorders. Studies suggest that commercial motor vehicle (CMV) operators have a higher prevalence of OSA than the general population. U.S. federal statute requires CMV drivers to undergo medical qualification examinations at least every 2 years—the federal medical standard that deals with OSA is section 49 CFR 391.41(b)(5) of the Federal Motor Carrier Safety Regulations. This section states that the driver must have “no established medical history or clinical diagnosis of respiratory dysfunction likely to interfere with the ability to control and drive a commercial motor vehicle safely.” Recently, the Federal Motor Carrier Safety Administration (FMCSA) changed the medical examination reporting form to include a question that asks a driver whether he or she has a sleep disorder, pauses in breathing while asleep, daytime sleepiness, or loud snoring. So far, the only guidance available from FMCSA on the diagnosis and treatment of OSA in CMV drivers was issued in 1991, the result of a report from a conference sponsored by the Federal Highway Administration. However, in the past 15 years, there has been a tremendous increase in the scientific and clinical knowledge regarding the diagnosis and treatment of OSA. This new information is not reflected in the current FMCSA guidance and has created challenging and, at times, conflicting approaches to managing OSA in commercial drivers. Because public safety has always been of the highest priority when determining acceptable risk in relation to medical conditions in CMV drivers (this differs significantly from the usual approach in clinical medicine), it is well accepted that when assessing risk of accidents due to a medical condition, CMV drivers are held to a higher medical standard than the general population. Given the public safety risks associated with OSA, its prevalence in the CMV driver population, and the fact that the guidance on OSA diagnosis and management is 15 years old, the American College of Chest Physicians, the American College of Occupational and Environmental Medicine, and the National Sleep Foundation convened a Task Force to address this important safety and medical risk in CMV drivers. The Task Force pursued the following activities: 1) review the existing scientific literature related to the diagnosis and management of OSA; 2) review the medical standards and guidelines related to OSA from U.S. Department of Transportation agencies and equivalent international groups; 3) review other relevant reports and recommendations from the National Transportation Safety Board, FMCSA, and others; 4) draft a preliminary document of findings; 5) develop recommendations related to screening, diagnosis, treatment, return to work, and follow up; and 6) address other relevant topics such as compliance, duration of certification, and research needs. This report of the Task Force provides the detailed findings of the extensive reviews conducted of documents from diverse resources on many relevant topics. The detailed reviews address the following areas: 1) definition of sleep apnea; 2) current regulations, recommendations, and guidelines; 3) identification of patients at risk for sleep apnea and diagnosis; 4) objective assessment of sleepiness and performance; 5) identification of CMV drivers with sleep apnea who are at high risk for crashes; 6) management of sleep apnea in the CMV driver; 7) practical considerations; and 8) additional research questions. Findings formed the foundation for consensus recommendations regarding the diagnosis and management of OSA in commercial drivers. The information presented in the eight sections are not summarized here, but rather provided in detail with references in the report. The recommendation categories focus on the following: Screening; Diagnosis; Treatment; Compliance and efficacy; Return to work after treatment for OSA; and Follow up. The tables included in this article provide an overview of these recommendations. However, the Task Force recommends that the commercial driver medical examiner (CDME) evaluate each driver individually and make a judgment about his or her fitness for duty based on specific criteria, including those listed in the tables in this article. These criteria cannot predict every situation faced by the examiner, and the final judgment belongs to the CDME. Additional testing is optional, based on clinical judgment, to document absence of excessive somnolence.Table: Screening Recommendation for Commercial Drivers With Possible or Probable Sleep ApneaTable: Recommendation Regarding the Evaluation for Fitness-for-Duty for Commercial Drivers With Possible or Probable Sleep Apnea

Child restraint seating regulations modified

Two US Department of Transportation agencies are modifying their child restraint seating regulations to make it easier for persons traveling with small children to use the same safety seat in both their motor vehicles and on commercial airplane flights. At present, seats certified by the department's National Highway Traffic Safety Administration cannot be used on airliners without special certification from the Federal Aviation Administration, which also is part of the department. The new common standard is expected to go into effect next Feb 28. The department estimates that more than 600 small children die in traffic accidents in this country each year. It further estimates—from data submitted by state agencies—that two of three (67%) of the infants transported in motor vehicles now are placed in infant restraint seats, but that fewer than half (44%) of children between the ages of 1 and 4 years are placed in safety seats.