High-resolution connected vehicle (CV) trajectory and event data has recently become commercially available. With over 500 billion vehicle position records generated each month in the United States, these data sets provide unique opportunities to build on and expand previous advances on traffic signal performance measures and safety evaluation. This report is a synthesis of research focused on the development of CV-based performance measures. A discussion is provided on data requirements, such as acquisition, storage, and access. Subsequently, techniques to reference vehicle trajectories to relevant roadways and movements are presented. This allows for performance analyses that can range from the movement- to the system-level. A comprehensive suite of methodologies to evaluate signal performance using vehicle trajectories is then provided. Finally, uses of CV hard-braking and hard-acceleration event data to assess safety and driver behavior are discussed. To evaluate scalability and test the proposed techniques, performance measures for over 4,700 traffic signals were estimated using more than 910 million vehicle trajectories and 14 billion GPS points in all 50 states and Washington, D.C. The contents of this report will help the industry transition towards a hybrid blend of detector- and CV-based signal performance measures with rigorously defined performance measures that have been peer-reviewed by both academics and industry leaders.
Many agencies use Automated Traffic Signal Performance Measures (ATSPMs), which require vehicle detection and communication equipment, to evaluate traffic signal efficiency. ATSPMs usually rely on projections based on spatially limited vehicle trajectory samples to estimate performance. Recently, connected vehicle (CV) data has become available that provides entire vehicle trajectories that can be used to generate accurate signal performance measures without the need for projections or infrastructure upgrades. This paper analyzes over 50 intersections in Utah to evaluate how traditional detector-based arrivals on green (AOG) calculations compare with their CV-based calculations. The effects that saturation and queue- lengths have on estimations are analyzed. In general, there is close correlation between computations when queues are short and undersaturated conditions exist. However, if queues extend past the advance detector, detector-based calculations tend to overestimate AOG since vehicles are detected during green but may stop before. This impact is particularly large when the approach is oversaturated, which led to overestimations of around 40% in this study. In addition, detector-based estimations can underestimate AOG in undersaturated scenarios with short queues if vehicles reach the advance detector on red but reduce their speed afterwards, allowing them to not stop. In some cases, the detector-based technique underestimated AOG by over 50%. The findings can help practitioners understand how detector-based estimations vary by traffic conditions. This is particularly important as the industry moves toward a hybrid blend of detector- and CV-based signal performance measures. It is recommended that CV trajectories be used to measure AOG during periods with long queues, oversaturated conditions, or both.
The Aviation Security world changed drastically following the terrorist attacks of September 11th, 2001. In this paper we look at 1) the changes that occurred to the aviation security sector and 2) how the United States aviation security compares to other parts of the world. Currently the United States has the most expensive aviation security infrastructure in the world. The main motivation of this topic was to find out why the United States was spending so much and assessing whether its aviation security sector was economically efficient. In this paper the authors provide the history of aviation security and the changes that took place post 9/11. A cost breakdown is presented and whether the amount of money being spent is worth the benefits received is discussed. This study also compares the United States' aviation security to that of Europe and Canada. These comparisons analyze how the total expenditure for the U.S. Transportation Security Administration (TSA) is similar/dissimilar to the aviation security expenditures in Europe and Canada. Recommendations for future budgets and tax revenues are also made. Overall, it is concluded that the amount of TSA's spending on aviation security is justified.
Traffic signal performance measures based on connected vehicle (CV) trajectory data can provide practitioners actionable information on the operational state of their systems. A visualization framework that can enable agencies to quickly assess arterial-level performance by time-of-day (TOD) to identify challenges and opportunities has been recently developed. The framework provides information on four relevant signal performance measures over a corridor, including traditional Highway Capacity Manual (HCM) level of service (LOS), arrivals on green (AOG), split failures (SF), and downstream blockage (DSB). This document uses the proposed framework to provide 58 arterial-level performance reports analyzing 571 unique signalized intersections on 42 corridors in 14 different states. Results are estimated from over 18,000,000 vehicle trajectories and 328,000,000 GPS points. Since the reporting approach can provide up to 3,072 performance data points per intersection, this manuscript provides almost 2 million measures for all the analyzed locations.
Since the invention of the car, the built transportation environment is becoming increasingly more automobile focused. The creation of auto-oriented roadways and increased automobile usage is in direct contrast with the decrease of more active transportation modes, such as walking, biking, or public transit transportation. Although personal automobiles may save users' time in traveling, there is a growing concern, backed by numerous studies, regarding the health effects directly and indirectly caused by increased automobile dependence and the auto-oriented transportation environment. The present report explores the many health related problems that are correlated with the current transportation environment, including reduced physical activity, obesity, respiratory problems, and mental health issues, particularly in the United States. The findings indicate that the modern built transportation system indeed influences many aforementioned problems, and that there must be engineering and societal responses to both encourage and allow greater opportunities for active transportation. The report further discusses the responses that have already taken place and planning measures to foster more active transportation in the future. Finally, it focuses on the development of a land-use planning health index, which would force land-use planners to identify active transportation needs and create a standard for the accessibility of active transportation within communities.
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