Influence of Bridge Facility Attributes on Bicycle Travel Behavior

An unlabeled multinomial logit model is developed to estimate the impact bridge facility attributes have on bicycle travel behavior. Data were collected in Austin, Texas, via a GPS-based smartphone application. Three attributes are analyzed and interacted with varied demographic and trip purpose information: bridge accessibility, vehicular volume, and traffic separation. Due to the significant investment in bicycle facilities at the local, state, and federal levels and the increase in urban bicycle use, it is imperative that agencies fully understand the behavioral elements underlying bicycle travel patterns. Transportation planners cannot assume bicyclists are solely focused on minimizing travel time or distance—standard practice assumptions for vehicular modes. This paper focuses on the analysis of bridge characteristics that are attractive to bicyclists. While several others have looked at bicycle facility preferences, this is the first paper to focus exclusively on bridges. Bridge facilities are fundamentally different from the res

A farewell to brake reaction times? Kinematics-dependent brake response in naturalistic rear-end emergencies

Driver braking behavior was analyzed using time-series recordings from naturalistic rear-end conflicts (116 crashes and 241 near-crashes), including events with and without visual distraction among drivers of cars, heavy trucks, and buses. A simple piecewise linear model could be successfully fitted, per event, to the observed driver decelerations, allowing a detailed elucidation of when drivers initiated braking and how they controlled it. Most notably, it was found that, across vehicle types, driver braking behavior was strongly dependent on the urgency of the given rear-end scenario’s kinematics, quantified in terms of visual looming of the lead vehicle on the driver’s retina. In contrast with previous suggestions of brake reaction times (BRTs) of 1.5 s or more after onset of an unexpected hazard (e.g., brake light onset), it was found here that braking could be described as typically starting less than a second after the kinematic urgency reached certain threshold levels, with even faster reactions at higher urgencies. The rate at which drivers then increased their deceleration (towards a maximum) was also highly dependent on urgency. Probability distributions are provided that quantitatively capture these various patterns of kinematics-dependent behavioral response. Possible underlying mechanisms are suggested, including looming response thresholds and neural evidence accumulation. These accounts argue that a naturalistic braking response should not be thought of as a slow reaction to some single, researcher-defined “hazard onset”, but instead as a relatively fast response to the visual looming cues that build up later on in the evolving traffic scenario

Transferability of Car-Following Models Between Driving Simulator and Field Traffic

During the past few decades, there have been two parallel streams of driving behavior research: models using trajectory data collected from the field (using video recordings, GPS, etc.) and models using data from driving simulators (in which the behavior of the drivers is recorded in controlled laboratory conditions). Although the former source of data is more realistic, it lacks information about the driver and is typically not suitable for testing effects of future vehicle technologies and traffic scenarios. In contrast, driving behavior models developed with driving simulator data may lack behavioral realism. However, no previous study has compared these two streams of mathematical models and investigated the transferability of the models developed with driving simulator data to real field conditions in a rigorous manner. The current study aimed to fill this research gap by investigating the transferability of two car-following models between a driving simulator and two comparable real-life traffic motorway scenarios, one from the United Kingdom and the other one from the United States. In this regard, stimulus–response–based car-following models were developed with three microscopic data sources: (a) experimental data collected from the University of Leeds driving simulator, (b) detailed trajectory data collected from UK Motorway 1, and (c) detailed trajectory data collected from Interstate 80 in California. The parameters of these car-following models were estimated by using the maximum likelihood estimation technique, and the transferability of the models was investigated by using statistical tests of parameter equivalence and transferability test statistics. Estimation results indicate transferability at the model level but not fully at the parameter level for both pairs of scenarios

Lead-Free Gunshot Residues as Forensic Evidence

The analysis of gunshot residue (GSR) has been forensically relevant for many years and several methods are well characterized in scientific literature. However, the manufacture and distribution of lead-free alternatives to small caliber firearms ammunition is increasing rapidly as these types of rounds are more environmentally friendly and safer for use in indoor shooting ranges. Removing lead-containing compounds (e.g., lead styphnate) from the primer mixture eliminates a significant chemical marker vital to the legal precedent governing GSR analysis. The American Society for Testing and Materials (ASTM) standard ASTM E1588-95 is no longer applicable to such residues. With this emerging market, the forensic community must develop and validate methods aimed at the detection of lead-free GSR on the hands of suspected shooters. This study investigated the use of Laser-Induced Breakdown Spectroscopy (LIBS) and Scanning Electron Microscopy Energy-Dispersive X-ray Spectroscopy (SEM-EDX) as means of characterizing simulations of lead-free primers and GSR originating from the discharge of lead-free blank training rounds, typically used by law enforcement. As a result, forensic investigators will be provided with: a chemical profile for lead-free GSR using LIBS; the fully characterized rates of error associated with this method for shooters and non-shooters; and the lifetime that forensically relevant quantities of lead-free GSR can be recovered from the hands of a suspected shooter. Additionally, this study serves as the first recorded comparison in the analysis of lead-free GSR via LIBS as a rapid and relatively non-destructive screening method followed by confirmation with SEM-EDX on the preserved evidence

Management of placenta accreta: evaluate the relationship between cervical length and obstetrical outcome in women with placenta accreta

Prior studies have associated short cervix in the setting of placenta previa with adverse obstetric outcomes including maternal hemorrhage, preterm birth, emergency cesarean and abnormally adherent placenta. However, the association between cervical length and placenta accreta has not been evaluated. The aim of this study was to demonstrate the relationship between cervical length and preterm delivery in patients with placenta accreta with the goal of identifying additional prognostic factors to improve our ability to treat women with placenta accreta

Management of placenta accreta: evaluate the relationship between cervical length and obstetrical outcome in women with placenta accreta

Prior studies have associated short cervix in the setting of placenta previa with adverse obstetric outcomes including maternal hemorrhage, preterm birth, emergency cesarean and abnormally adherent placenta. However, the association between cervical length and placenta accreta has not been evaluated. The aim of this study was to demonstrate the relationship between cervical length and preterm delivery in patients with placenta accreta with the goal of identifying additional prognostic factors to improve our ability to treat women with placenta accreta

A Case Study on Street Design

This paper will look at several contemporary theories of street design in order to get a better understanding of how streets in Atlanta could be redesigned and repur¬posed with the understanding of streets as being “sym¬bolic, ceremonial, social, and political places [Jacobs 5].” I will begin first by analyzing the history of the street as it was established throughout ancient Rome, 15th century Renaissance, the Medieval era, Baroque, New York in the 1900s, and modern day suburbia in order to give context to the theoretical ideas that are currently being applied. Then I will look at some of the issues in the design of streets, in order to understand why streets are so difficult to design. Finally, I will analyze each theory through the use of case studies in order to understand how they dealt with and overcame the issues of street design and how these theories might be applicable to Atlanta

A combat simulation analysis of the amphibious assault vehicle in countermine operations

The purpose of this thesis is to evaluate the effectiveness of an Amphibious Assault Vehicle (AAV) as a mine countermeasure in the surf zone and beach zone (sz/bz). In order to show the utility of these approaches, this thesis presents results from three different scenarios. Scenario one provides a baseline and is conducted with the amphibious landing force moving onshore with no minefield breaching operations being conducted. Scenario two encompasses a more traditional method of minefield breaching. Scenario three will use AAVs only to breach the surf zone and beach zone minefields. The focus will be placed on the number of mines neutralized as well as the number of assets killed.http://archive.org/details/acombatsimulatio1094513676U.S. Navy (U.S.N.) author