Suchergebnisse

Abstract
Research question
How accurately can all locations of 44 fatal collisions in 1 year be forecasted across 1403 micro-areas in Toronto, based upon locations of all 1482 non-fatal collisions in the preceding 4 years?

Data
All 1482 non-fatal traffic collisions from 2008 through 2011 and all 44 fatal traffic collisions in 2012 in the City of Toronto, Ontario, were geocoded from public records to 1403 micro-areas called 'hexagonal tessellations'.

Methods
The total number of non-fatal traffic collisions in Period 1 (2008 through 2011) was summed within each micro-area. The areas were then classified into seven categories of frequency of non-fatal collisions: 0, 1, 2, 3, 4, 5, and 6 or more. We then divided the number of micro-areas in each category in Period 1 into the total number of fatal traffic collisions in each category in Period 2 (2012). The sensitivity and specificity of forecasting fatal collision risk based on prior non-fatal collisions were then calculated for five different targeting strategies.

Findings
The micro-locations of 70.5% of fatal collisions in Period 2 had experienced at least 1 non-fatal collision in Period 1. In micro-areas that had zero non-fatal collisions during Period 1, only 1.7% had a fatal collision in Period 2. Across all areas, the probability of a fatal collision in the area during Period 2 increased with the number of non-fatal collisions in Period 1, with 6 or more non-fatal collisions in Period 1 yielding a risk of fatal collision in Period 2 that was 8.7 times higher than in areas with no non-fatal collisions. This pattern is evidence that targeting 25% of micro-areas effectively could cut total traffic fatalities in a given year by up to 50%.

Conclusion
Highly elevated risks of traffic fatalities can be forecasted based on prior non-fatal collisions, targeting a smaller portion of the city for more concentrated investment in saving lives.

Since the emergence of commercial aviation in the early part of last century, economic forces have driven a steadily increasing demand for air transportation. Increasing density of aircraft operating in a finite volume of airspace is accompanied by a corresponding increase in the risk of collision, and in response to a growing number of incidents and accidents involving collisions between aircraft, governments worldwide have developed air traffic control systems and procedures to mitigate this risk. The objective of any collision risk management system is to project conflicts and provide operators with sufficient opportunity to recognize potential collisions and take necessary actions to avoid them. It is therefore the assertion of this research that the currency of collision risk management is time. Future Air Traffic Management Systems are being designed around the foundational principle of four dimensional trajectory based operations, a method that replaces legacy first-come, first-served sequencing priorities with time-based reservations throughout the airspace system. This research will demonstrate that if aircraft are to be sequenced in four dimensions, they must also be separated in four dimensions. In order to separate aircraft in four dimensions, time must emerge as the primary tool by which air traffic is managed. A functional relationship exists between the time-based performance of aircraft, the interval between aircraft scheduled to cross some three dimensional point in space, and the risk of collision. This research models that relationship and presents two key findings. First, a method is developed by which the ability of an aircraft to meet a required time of arrival may be expressed as a robust standard for both industry and operations. Second, a method by which airspace system capacity may be increased while maintaining an acceptable level of collision risk is presented and demonstrated for the purpose of formulating recommendations for procedures regulating air traffic management methods and industry standards governing performance requirements for avionics designed to support trajectory based operations.

The propensity of fatal traffic collisions transcends driver age and reinforces the need to evaluate, among other factors, the impact of roadway lighting and other features of driver vision, perception, and performance. Collisions may result from a driver's inability to notice delineation, recognize warnings, and other possible road safety controls during various lighting conditions. Hence we compare the relative accident involvement ratio (RAIR) of collisions of millions of drivers from two U.S. States over an 11‐year period, 1991–2001. We associate collision trends through RAIR with bathtub curves that are commonly identified with product failure and reliability engineering. Hence we observe the need for improved and automated driver's license testing techniques and applications, especially as these relate to the visual and cognitive abilities of drivers of all ages. Our findings may ultimately improve motorist safety, save lives, and benefit numerous other states, countries, and agencies, including, but not limited to, aviation, commercial vehicles, maritime, and rail sectors, among others.

AbstractThis article investigates the utility and extension of well‐established collision risk modeling approaches for lateral separation standard development for unmanned traffic management and network design. The applicability of standard assumptions and simplifications made in the manned environment to a scaled‐down unmanned aerial systems (UAS) environment is first investigated. The results are used to derive an iso‐risk surface that shows the tradeoff between separation distance and navigation performance for a given risk level or target level of safety. The model is then extended to consider collision risk from one to tracks, and finally to determine the total collision risk and the related iso‐risk surfaces for systems of parallel tracks with additions to account for the effects of more than two parallel tracks. The extended model is applied to a case study where airspace design for an urban area is conducted via maximization of the number of same‐direction parallel tracks while meeting the target level of safety. The results suggest that lateral separation distances less than 100 m are achievable for small UAS, and that the separation standards are mostly affected by the proportion of poorly navigating aircraft.

AbstractWe propose an innovative time‐varying collision risk (TCR) measurement for ship collision prevention in this article. The proposed measurement considers the level of danger of the approaching ships and the capability of a ship to prevent collisions. We define the TCR as the probability of the overlap of ships' positions in the future, given the uncertainty of maneuvers. Two sets are identified: (1) the velocity obstacle set as the maneuvers of the own ship that lead to collisions with target ships, and (2) the reachable velocity set as the maneuvers that the own ship can reach regarding its maneuverability. We then measure the TCR as the time‐dependent percentage of overlap between these two sets. Several scenarios are presented to illustrate how the proposed measurement identifies the time‐varying risk levels, and how the approach can be used as an intuitively understandable tool for collision avoidance.

This thesis evaluates the risk of ship collisions in the Barents Sea in 2030 between three future scenarios; Minimum, Basis and Maximum Scenario. IWRAP Mk2 program is utilized to make the calculations. Automatic Identification System (AIS) data of 2013 is used to parameterize current traffic density, while the increased traffic in the different scenarios is derived from an analysis of multiple sources, including Rystad Petro Foresight, government documents and reports from DNV. The petroleum production in the North Sea is expected to decline, while exploration and production in the Northern part Norway is expected to increase. This will lead to that the Barents Sea will be a major contributor to oil and gas production, instead of the North Sea and the southern Norwegian Sea towards the end of 2030s. The petroleum industry is on its way north to an area that earlier mainly has been associated with high fishing activity, but may now be more dominated by larger supply vessels. This change will cause an increase in ship traffic in the area, and the probability of ship collisions may therefore be elevated. The issues discussed in this report are important for the industry, and necessary for predicting the future risk picture in the Barents Sea. It is vital to idenfity the future risk of ship collision with regards to the increase in ship traffic due to the potential consequences with respect to the harsh and vulnerable environment and lack of infrastructure in the northern part of Norway. This thesis will investigate how the probability of ship collision change, and also identify the risk of ship collisions in the Barents Sea within the different scenarios of petroleum development. There are five types of collision between ships which are taken into account in this thesis, these are; Head on collsion, crossing collsion, overtaking collsion, bend collision and merge collsion. The thesis will answer the research problems regarding to how the environmental conditions in the Barents Sea are, how the increased offshore-related traffic increase the probability of ship collision in the Barents Sea in 2030, and how the risk of ship collisions change between the three scenarios. The results show that there will be significantly differens in the likelihood for ship collisions in the three scenarios. The total likelihood for minimum scenario is 5,80E-04 incidents/year, while the likelihood in basis and maximum scenario is calculated to 1,8E-03 and 1,75E-03. The final leg into `Polarbase` (Hammerfest) is the leg in all scenarios that will have the greatest likelihood for ship collisions, and will also be the most critical leg with respect to the high density of ships in it, despite its short length. The ship type that will be the biggest contributer to ship collisions is both support ships and crude oil tankers, these collisions will be by type; head on collision and overtaking collision. A critical situation will occur in the Barents Sea if a ship collision takes place, and especially collisions with crude oil tankers with its chemicals. This will put great demand on the oil spill management in the region.