Search

This paper presents the concept of a living laboratory (LL) and how it is applied to transportation operations research through a case study. This case study focuses on calibrating the Wiedemann car-following model parameters specific to freeway work zones. Applying the concept of an LL enables the experimental platform to be in a natural real-world environment. The design of this LL included the development of an instrumented research vehicle (IRV) to capture the natural car-following response of a driver when entering and passing through a freeway work zone. The development of a connected mobile traffic sensing (CMTS) system, which included state-of-the-art intelligent transportation systems (ITS) technologies, supports the LL environment by providing the connectivity, interoperability, and data processing of the natural, real-life setting. The IRV and CMTS system are tools designed based on the research objective to support the concept of an LL which facilitates the experimental environment to capture and calibrate natural driver behavior. This case study shows the application of an LL specific to operations research providing an experimental platform for evaluating the operational performance of a roadway in a real-time, connected, and collaborative natural environment. [ABSTRACT FROM AUTHOR]

This paper describes the development of a systematic methodology for identifying and ranking bottlenecks using probe data collected by commercial global positioning system fleet management devices mounted on trucks. These data are processed in a geographic information system and assigned to a roadway network to provide performance measures for individual segments. The authors hypothesized that truck speed distributions on these segments can be represented by either a unimodal or bimodal probability density function and proposed a new reliability measure for evaluating roadway performance. Travel performance was classified into three categories: unreliable, reliably fast, and reliably slow. A mixture of two Gaussian distributions was identified as the best fit for the overall distribution of truck speed data. Roadway bottlenecks were ranked on the basis of both the reliability and congestion measurements. The method was used to evaluate the performance of Washington state roadway segments, and proved efficient at identifying and ranking truck bottlenecks. [ABSTRACT FROM AUTHOR]

Recent technological advances have made it both feasible and practical to identify unsafe driving behaviors using second-by-second trajectory data. Presented in this paper is a unique approach to detecting safety-critical events using vehicles’ longitudinal accelerations. A Discrete Fourier Transform is used in combination with K-means clustering to flag patterns in the vehicles’ accelerations in time-series that are likely to be crashes or near-crashes. The algorithm was able to detect roughly 78% of crasjavascript:void(0)hes and near-crashes (71 out of 91 validated events in the Naturalistic Driving Study data used), while generating about 1 false positive every 2.7 h. In addition to presenting the promising results, an implementation strategy is discussed and further research topics that can improve this method are suggested in the paper. [ABSTRACT FROM AUTHOR]

The design of mini-roundabouts has been around and practiced in Europe for decades. It has been a successful and low-cost intersection configuration using existing external boundaries of intersections. Nevertheless, accessible traffic capacity models for mini-roundabouts do not exist. This study provides design recommendations and a simulation approach for capacity models of mini-roundabouts from U.S. data. Two geometries are selected that have a 7 or 10 m (24- or 36-ft) approach width typical of conventional intersections. The mini-roundabouts are best defined by the inscribed circle diameter of 15 and 23 m (50 and 75 ft). Field data are collected on drivers' behavior and decisions for a mini-roundabout design in order to calibrate simulation models. A microscopic traffic simulation software is used to model the selected prototype designs for capacity estimations. The defining feature for mini-roundabouts is the traversable central and splitter islands for large vehicles that make through or left-turn movements. The linear regression models presented estimate the capacity of the mini-roundabouts to be lower than that of the single-lane roundabout. However the mini-roundabout has a higher capacity per square foot of land, which would be an innovative solution for urban areas for increasing capacity at existing all-way stop-controlled intersections at lower cost than single-lane roundabouts. [ABSTRACT FROM AUTHOR]