世界経済・社会統計 = World development indicators

Highway Capacity Manual改訂の動向--テイラ-教授の講演より

Generalized Linear Models (2nd ed.)

Gaining a better understanding of the factors that affect the likelihood of a vehicle crash has been an area of research focus for many decades. However, in the absence of detailed driving data that would help improve the identification of cause and effect relationships with individual vehicle crashes, most researchers have addressed this problem by framing it in terms of understanding the factors that affect the frequency of crashes - the number of crashes occurring in some geographical space (usually a roadway segment or intersection) over some specified time period. This paper provides a detailed review of the key issues associated with crash-frequency data as well as the strengths and weaknesses of the various methodological approaches that researchers have used to address these problems. While the steady march of methodological innovation (including recent applications of random parameter and finite mixture models) has substantially improved our understanding of the factors that affect crash-frequencies, it is the prospect of combining evolving methodologies with far more detailed vehicle crash data that holds the greatest promise for the future.

http://ceprofs.tamu.edu/dlord/Papers/Lord-Mannering_Review.pdf

The statistical analysis of crash-frequency data: A review and assessment of methodological alternatives

Artificial intelligence research is ushering in a new era of sophisticated, mass-market transportation technology. While computers can already fly a passenger jet better than a trained human pilot, people are still faced with the dangerous yet tedious task of driving automobiles. Intelligent Transportation Systems (ITS) is the field that focuses on integrating information technology with vehicles and transportation infrastructure to make transportation safer, cheaper, and more efficient. Recent advances in ITS point to a future in which vehicles themselves handle the vast majority of the driving task. Once autonomous vehicles become popular, autonomous interactions amongst multiple vehicles will be possible. Current methods of vehicle coordination, which are all designed to work with human drivers, will be outdated. The bottleneck for roadway efficiency will no longer be the drivers, but rather the mechanism by which those drivers' actions are coordinated. While open-road driving is a well-studied and more-or-less-solved problem, urban traffic scenarios, especially intersections, are much more challenging.

We believe current methods for controlling traffic, specifically at intersections, will not be able to take advantage of the increased sensitivity and precision of autonomous vehicles as compared to human drivers. In this article, we suggest an alternative mechanism for coordinating the movement of autonomous vehicles through intersections. Drivers and intersections in this mechanism are treated as autonomous agents in a multiagent system. In this multiagent system, intersections use a new reservation-based approach built around a detailed communication protocol, which we also present. We demonstrate in simulation that our new mechanism has the potential to significantly outperform current intersection control technology--traffic lights and stop signs. Because our mechanism can emulate a traffic light or stop sign, it subsumes the most popular current methods of intersection control. This article also presents two extensions to the mechanism. The first extension allows the system to control human-driven vehicles in addition to autonomous vehicles. The second gives priority to emergency vehicles without significant cost to civilian vehicles. The mechanism, including both extensions, is implemented and tested in simulation, and we present experimental results that strongly attest to the efficacy of this approach.

/pdf/a-multiagent-approach-to-autonomous-intersection-management-ndv1gqtnse.pdf

A multiagent approach to autonomous intersection management

Travel along a ramp can present drivers with complex alignment changes and decision points. These changes and complexities can increase the potential for conflict or crash, especially for larger vehicles. A few studies have examined the effect of variables on ramp crash frequency. However, none of these studies considered the effect of variables on crash severity distributions. Relatively little or no information is available about the safety effects of design elements on the severity of ramp crashes. In some cases, countermeasures (such as longitudinal barriers) are implemented to reduce fatal crashes, but the effect of these treatments on less severe crashes is not well understood. New research has been conducted to develop severity distribution functions (SDFs) for ramp segments and signalized and unsignalized crossroad ramp terminals for predicting the proportion of crashes in each severity category as a function of roadway geometric design elements and traffic control features. The SDFs were calibrat...

Analysis of Injury Severity in Crashes on Ramps and at Crossroad Ramp Terminals

Crash–frequency modeling

Environmental Conscious Highway Design for Vertical Crest Curves

Over the five-year period of 2007 through 2011, 2,232 fatal pedestrian crashes were recorded in Texas. 21% of these crashes were found to have occurred on controlled-access facilities (i.e. freeways). This is an alarmingly high number for a location where pedestrians are least expected. This study analyzed crash reports and police officer narratives to understand the characteristics and contributing factors associated with fatal pedestrian crashes on freeways. The contributing factors identified include pedestrian and driver alcohol use and dark conditions. Eighty percent of the crashes occurred after dark, almost half of which were at a location with no lighting. Intoxicated pedestrians were involved in twenty eight percent of crashes, with an average BAC of 0.20. To alleviate this problem, there may be a need for conducting a “Don’t Drink and Walk” campaign to educate the general public of dangers of walking while intoxicated, especially at night. A quarter of the crashes involved unintended pedestrians, i.e. those who were out of their vehicle due to a previous crash or a stalled vehicle. Motorists should be educated to not work on their vehicle in traffic and not to try and cross the freeway to reach a shoulder or median. It is best to wait in the vehicle with seat belt and hazard lights on until emergency services arrive.

https://ceprofs.civil.tamu.edu/dlord/Papers/Iragavarapu_et_al_Fatal_Freeway.pdf

Pedestrian fatal crashes on freeways in texas

A visual approach for defining the spatial relationships among crashes, crimes, and alcohol retailers: Applying the color mixing theorem to define the colocation pattern of multiple variables.

Dominique Lord

Papers

Analysis of Injury Severity in Crashes on Ramps and at Crossroad Ramp Terminals

Crash–frequency modeling

Environmental Conscious Highway Design for Vertical Crest Curves

Pedestrian fatal crashes on freeways in texas

A visual approach for defining the spatial relationships among crashes, crimes, and alcohol retailers: Applying the color mixing theorem to define the colocation pattern of multiple variables.