Development of Guidance for Unsignalized Intersections on Rural Multilane Divided Highways

This research project examines the safety performance of unsignalized intersections on rural divided highways in Alabama. A summary of the safety problem at these intersections is provided; the concern is the relatively high frequency and severity of crashes at these locations, typically associated with vehicles entering from the minor road and failing to successfully cross or turn left onto the second directional roadway. The project objectives included review of the literature, examination of a small set of such intersections in Alabama with innovative treatments, factors that influence safety performance and approaches to estimating performance, and developing design guidance for these locations. During the course of this study, ALDOT developed an Intersection Control Evaluation (ICE) policy, which to some extent addresses the last objective. This study reviewed the literature, estimated calibration factors for safety performance functions for three-leg and four-leg intersections of this type, reviewed geometric and traffic control features that may improve safety performance, and examined differences in safety performance among several selected intersections in Alabama. A review of the literature and current practice found many treatments with respect to geometrics and traffic control devices that can be applied to the conventional form of this type of intersection with the goal of reducing crash frequency and crash severity. An analysis involving 47 three-leg and 65 four-leg intersections in the state yielded recommend calibration factors for the relevant safety performance functions. Several selected sites with atypical design and traffic control treatments were reviewed. Finally, a traffic conflict study across several intersections with conventional and unconventional treatments was conducted to further identify the types of conflicts that contribute to poor safety performance

Influence of Collaborative Curriculum Design on Educational Beliefs, Communities of Practitioners, and Classroom Practice in Transportation Engineering Education

The development and widespread implementation of best practices in transportation engineering classrooms is important in attracting and retaining the next generation of transportation engineers. Engineering education professionals have uncovered many best practices in the field; however, the process of effectively disseminating and ultimately achieving the widespread adoption of these best practices by others is not yet well understood. Sixty participants, comprising faculty members, Ph.D. students, and public sector employees, attended a Transportation Engineering Education Workshop convened in Seattle, WA to promote the collaborative development and adoption of active learning and conceptual exercises in the introduction to transportation engineering class. Participant assessments were conducted in the form of pre-, post-, and follow-up surveys. Results showed immediately positive shifts in participant beliefs about the importance of active learning and conceptual exercises with declines during the follow-up period, an increased density and connectivity of curriculum development networks, and extensive reports of valuable experiences and influences from the workshop.KEYWORDS: National Transportation Curriculum Project, (NTCP), Adoption of Innovation, Workshops, Conceptual Change, Active Learning, Introduction to Transportation Engineerin

Assessment of the Introductory Transportation Engineering Course and the General Transportation Engineering Curriculum

Transportation engineering is a critical subdiscipline of the civil engineering profession as indicated by its inclusion on the Fundamentals of Engineering Examination, its overlap with other specialty areas of civil engineering, and as recognized by the Transportation Research Board, Institute of Transportation Engineers, and the American Society of Civil Engineers. With increasing transportation workforce needs, low numbers of students entering the ‘pipeline’, and limited hours within undergraduate civil engineering programs, it is important to ensure civil engineering students receive adequate preparation and exposure to career opportunities in the transportation engineering field. As such, investigations into the status of transportation engineering within civil engineering programs and specifically the introductory transportation engineering course are essential for understanding the implications to the profession. This paper presents a review of relevant literature and findings from a new survey of ABET-accredited civil engineering programs that yielded 84 responses. The survey indicates that 88 percent of responding programs teach an introductory course in transportation engineering, and 79 percent require it in their undergraduate programs. There is significant variation in the structure of the introductory course (number of credit hours, lab requirements, etc.), and common responses regarding improvements that could be made include adding labs, requiring a second course, and broadening course content. In addition, nearly 15 percent of instructors teaching the introductory course did not have a primary focus in transportation engineering. This finding should be investigated further, given that this course may be an undergraduate civil engineering student’s only exposure to the profession.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the Transportation Research Board of the National Academies and can be found at: https://doi.org/10.3141/2328-0

Determining the Causes of Seasonal Variation in Pavement Friction: Observational Study with Datapave 3.0 Database

Large amounts of money are spent by departments of transportation to provide adequate pavement skid resistance, yet the mechanics of pavement friction are poorly characterized and not fully understood. Seasonal variations in skid resistance are often observed, and in some cases these variations may be large enough to significantly affect highway safety. This paper assesses two common theories for the cause of seasonal variations in skid resistance from the perspective of the conservation of energy to understand their influence on highway skid resistance. One theory states that the seasonal variations in skid resistance occur because snowfall removal operations increase microtexture, which is then worn away throughout the summer. The other theory states that seasonal variations are caused by seasonal differences in pavement temperature. This paper analyzes the Datapave 3.0 friction data to examine the extent to which snowfall removal operations and pavement temperatures influence highway skid resistance. The results show that although there is a significant relationship between temperature and skid number, there is no significant relationship between snowfall and skid number. This suggests that seasonal variations in pavement friction are dependent upon factors not related to surface texture and gives validity to an energy-based interpretation of the physics of the tire–pavement interface. Monthly adjustments for skid numbers were calculated and compared with those currently used by the Virginia Department of Transportation. This comparison showed significant agreement between the developed model and in-place practices

HIGHWAY PROJECT COST ESTIMATI NG METHODS USED IN THE PLANNING STAGE OF PROJECT DEVELOPMENT VIRGINIA TRANSPORTATION RESEARCH COUNCIL TECHNICAL ASSISTANCE REPORT HIGHWAY PROJECT COST ESTIMATING METHODS USED IN THE PLANNING STAGE OF PROJECT DEVELOPMENT

INTRODUCTION Highway project cost estimation methods that are used in the planning process have recently become a significant concern for the Virginia Department of Transportation (VDOT) because of the impact that these estimates have on the final cost of a project. Furthermore, metropolitan planning organizations (MPOs), local and federal government agencies, and the news media have increased their oversight regarding the accuracy of the results. The purpose of this report was to conduct a literature review of the methods used in highway cost estimation and to identify the state of the practice used by state DOTs for estimating highway project costs in the planning phase of project development. In recent years, increases in highway project cost estimates on VDOT projects have received attention from the news media and elected officials. For example, cost estimates of the Springfield Interchange Improvement Project, the junction of Interstates 95,395, and 495 in Fairfax County, increased by more than 60% between 1994 and 2000. The Joint Legislative Audit Review Commission of the General Assembly and the Office of Inspector General in the u.S. Department of Transportation investigated this project and the results were widely reported in the media. Fortunately, the Springfield interchange is not representative of most VDOT projects. Nonetheless, the factors influencing the increases in its cost estimates provide insight that may be transferable to more typical projects. This study is envisioned as a first step in an examination of practices for estimating highway project costs; therefore, its focus is on the initial cost estimate made for a project, typically during the planning stage. At this stage, only general information is known about the ultimate form a project will take and precise estimates of the quantities of project bid items (e.g., cubic yards of excavation) are not known. PURPOSE AND SCOPE The purpose of this study was to obtain and present information on available methods of estimating costs of highway projects during the planning process and for development of transportation improvement programs. The scope of this study was limited to methods for estimating highway project costs prior to the design phase of the project. This report does not present an evaluation of the methods used by VDOT or other state DOTs to develop project cost estimates. The study did not obtain data about the accuracy and efficacy of the processes used by state DOTs but intended simply to ascertain and synthesize the current state of the art and state of the practice regarding highway project cost estimating efforts made during the transportation planning process. METHODOLOGY The methods used in this study included a review of the literature pertaining to estimating transportation project costs, a review of current VDOT practice and of publications pertaining to VDOT's project cost estimates, and a survey of selected state DOTs to obtain information on their practices