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1 – 10 of over 11000Purpose – This chapter overviews surrogate measures of safety to help better understand the related challenges and opportunities. The chapter is meant to serve as a primer for…
Abstract
Purpose – This chapter overviews surrogate measures of safety to help better understand the related challenges and opportunities. The chapter is meant to serve as a primer for practitioners looking for alternative methods of evaluating safety where crashes are lacking or are insufficient.
Approach – The historical perspective and the current state-of-the-art thinking are presented in an organised manner with a focus on fundamental concepts, traffic measurement techniques and estimation of the relationships between surrogate events and collisions.
Findings – An analysis of the published research and its findings indicates that traffic conflicts are the most promising surrogates. They enable evaluation of the safety implications of a wide range of road and traffic conditions. The required ecological consistency between conflicts and collisions can be ensured by sufficient nearness of conflicts to collisions. Several methods of estimating the relationship between conflicts and crashes are discussed. Behavioural measures of safety are also discussed. Although easier to measure than conflicts, behavioural measures should be used with caution. Research on surrogate measures of safety may provide a basis for improving microsimulation models as tools of safety evaluation.
Practical implications – Current changes in vehicle and road instrumentation affect safety at a rate that exceeds the efficiency of the traditional crash-based methods of safety analysis. Accurate and quick measurement of safety with surrogate measures offers a viable solution. They are also a necessary condition of gaining a better understanding of safety and finding more effective solutions for safety problems.
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Randall K.Q. Akee, Arnab K. Basu, Nancy H. Chau and Melanie Khamis
Ethnic conflicts and their links to international human trafficking have recently received a surge in international attention. It appears that ethnic conflicts exacerbate the…
Abstract
Ethnic conflicts and their links to international human trafficking have recently received a surge in international attention. It appears that ethnic conflicts exacerbate the internal displacement of individuals from networks of family and community, and their access to economic and social safety nets. These same individuals are then vulnerable to being trafficked by the hopes of better economic prospects elsewhere. In this chapter, we empirically examine this link between ethnic fragmentation, conflicts, internally displaced persons, refugees, and international trafficking, making use of a novel dataset of international trafficking. We conduct a direct estimation, which highlights the ultimate impact of ethnic fragmentation and conflict on international trafficking through internal and international displacements.
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Zheng Xu, Yihai Fang, Nan Zheng and Hai L. Vu
With the aid of naturalistic simulations, this paper aims to investigate human behavior during manual and autonomous driving modes in complex scenarios.
Abstract
Purpose
With the aid of naturalistic simulations, this paper aims to investigate human behavior during manual and autonomous driving modes in complex scenarios.
Design/methodology/approach
The simulation environment is established by integrating virtual reality interface with a micro-simulation model. In the simulation, the vehicle autonomy is developed by a framework that integrates artificial neural networks and genetic algorithms. Human-subject experiments are carried, and participants are asked to virtually sit in the developed autonomous vehicle (AV) that allows for both human driving and autopilot functions within a mixed traffic environment.
Findings
Not surprisingly, the inconsistency is identified between two driving modes, in which the AV’s driving maneuver causes the cognitive bias and makes participants feel unsafe. Even though only a shallow portion of the cases that the AV ended up with an accident during the testing stage, participants still frequently intervened during the AV operation. On a similar note, even though the statistical results reflect that the AV drives under perceived high-risk conditions, rarely an actual crash can happen. This suggests that the classic safety surrogate measurement, e.g. time-to-collision, may require adjustment for the mixed traffic flow.
Research limitations/implications
Understanding the behavior of AVs and the behavioral difference between AVs and human drivers are important, where the developed platform is only the first effort to identify the critical scenarios where the AVs might fail to react.
Practical implications
This paper attempts to fill the existing research gap in preparing close-to-reality tools for AV experience and further understanding human behavior during high-level autonomous driving.
Social implications
This work aims to systematically analyze the inconsistency in driving patterns between manual and autopilot modes in various driving scenarios (i.e. multiple scenes and various traffic conditions) to facilitate user acceptance of AV technology.
Originality/value
A close-to-reality tool for AV experience and AV-related behavioral study. A systematic analysis in relation to the inconsistency in driving patterns between manual and autonomous driving. A foundation for identifying the critical scenarios where the AVs might fail to react.
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The purpose of this paper is to create a flight route optimization for all flights that aims to minimize the total cost consists of fuel cost, ground delay cost and air delay cost…
Abstract
Purpose
The purpose of this paper is to create a flight route optimization for all flights that aims to minimize the total cost consists of fuel cost, ground delay cost and air delay cost over the fixed route and free route airspaces.
Design/methodology/approach
Efficient usage of current available airspace capacity becomes more and more important with the increasing flight demands. The efficient capacity usage of an airspace is generally in contradiction to optimum flight efficiency of a single flight. It can only be achieved with the holistic approach that focusing all flights over mixed airspaces and their routes instead of single flight route optimization for a single airspace. In the scope of this paper, optimization methods were developed to find the best route planning for all flights considering the benefits of all flights not only a single flight. This paper is searching for an optimization to reduce the total cost for all flights in mixed airspaces. With the developed optimization models, the determination of conflict-free optimum routes and delay amounts was achieved with airway capacity and separation minimum constraints in mixed airspaces. The mathematical model and the simulated annealing method were developed for these purposes.
Findings
The total cost values for flights were minimized by both developed mathematical model and simulated annealing algorithm. With the mathematical model, a reduction in total route length of 4.13% and a reduction in fuel consumption of 3.95% was achieved in a mixed airspace. The optimization algorithm with simulated annealing has also 3.11% flight distance saving and 3.03% fuel consumption enhancement.
Research limitations/implications
Although the wind condition can change the fuel consumption and flight durations, the paper does not include the wind condition effects. If the wind condition effect is considered, the shortest route may not always cause the least fuel consumption especially under the head wind condition.
Practical implications
The results of this paper show that a flight route optimization as a holistic approach considering the all flight demand information enhances the fuel consumption and flight duration. Because of this reason, the developed optimization model can be effectively used to minimize the fuel consumption and reduce the exhaust emissions of aircraft.
Originality/value
This paper develops the mathematical model and simulated annealing algorithm for the optimization of flight route over the mixed airspaces that compose of fixed and free route airspaces. Each model offers the best available and conflict-free route plan and if necessary required delay amounts for each demanded flight under the airspace capacity, airspace route structure and used separation minimum for each airspace.
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Most of the existing approaches for flight collision avoidance are concerned with local traffic alone for which the separation is based on the pairwise analysis of aircraft…
Abstract
Purpose
Most of the existing approaches for flight collision avoidance are concerned with local traffic alone for which the separation is based on the pairwise analysis of aircraft trajectory trends, which is not efficient with regard to some flight path requirements along waypoints. The purpose of this paper is to deal with the global collision avoidance problem which aims at separating aircraft taking into consideration the global traffic in a given area instead of considering them pairwise. It aims to model the concept of global collision avoidance and propose a validated algorithm for the purpose in the framework of free‐flight.
Design/methodology/approach
The collision avoidance procedure computes online the appropriate speed and heading for each aircraft, at each sampling time‐instant, to generate a collision‐free flight trajectory along scheduled waypoints. The method accounts for automatic assignment of priority indexes that are updated from one control time horizon to the next. The paper considers here the case of aircraft flying at the same altitude, but the proposed method is easily extendable to the general 3D situation. Owing to the predictive features that are inherent to collision avoidance, the collision‐free trajectories are generated using model predictive control approach. A simulation example is presented in the end and its results show the suitability of the proposed approach.
Findings
Since the model predictive control approach is used, the collision avoidance procedure is anticipative; therefore, the avoidance capability depends only on the prediction horizon rather than on the control horizon.
Practical implications
The computation of the trajectory guidance information (speed and heading) at each time‐step is fast, therefore the proposed method is well suited for online processing requirements in real world applications.
Originality/value
The paper provides a flexible modelling framework and a computationally effective algorithm, both based on model predictive control concepts, to cope with global collision avoidance for flight safety enhancement in the framework of free‐flight.
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Purpose – To define, compare, and contrast human smuggling and trafficking, trace the route from recruitment and transportation to arrival at the destination and exploitation;…
Abstract
Purpose – To define, compare, and contrast human smuggling and trafficking, trace the route from recruitment and transportation to arrival at the destination and exploitation; examine some incorrect assumptions about human trafficking.
Methodology – Literature review of academic studies, conference presentations, and reports issued by governmental, non-governmental, and international organizations.
Findings – Instead of being an international phenomenon in which women and children are recruited with false promises of employment and then exploited by male members of highly organized international trafficking networks, research shows that victims – including men – are exploited in their own countries outside of the commercial sexual industry by women and by others operating as individuals or often in loosely organized networks.
Value – This article summarizes what is known about human trafficking including trafficking for human organs and for children used as child soldiers.
Mohamed M. Ahmed, Guangchuan Yang, Sherif Gaweesh, Rhonda Young and Fred Kitchener
This paper aims to present a summary of the performance measurement and evaluation plan of the Wyoming connected vehicle (CV) Pilot Deployment Program (WYDOT Pilot).
Abstract
Purpose
This paper aims to present a summary of the performance measurement and evaluation plan of the Wyoming connected vehicle (CV) Pilot Deployment Program (WYDOT Pilot).
Design/methodology/approach
This paper identified 21 specific performance measures as well as approaches to measure the benefits of the WYDOT Pilot. An overview of the expected challenges that might introduce confounding factors to the evaluation effort was outlined in the performance management plan to guide the collection of system performance data.
Findings
This paper presented the data collection approaches and analytical methods that have been established for the real-life deployment of the WYDOT CV applications. Five methodologies for assessing 21 specific performance measures contained within eight performance categories for the operational and safety-related aspects. Analyses were conducted on data collected during the baseline period, and pre-deployment conditions were established for 1 performance measures. Additionally, microsimulation modeling was recommended to aid in evaluating the mobility and safety benefits of the WYDOT CV system, particularly when evaluating system performance under various CV penetration rates and/or CV strategies.
Practical implications
The proposed performance evaluation framework can guide other researchers and practitioners identifying the best performance measures and evaluation methodologies when conducting similar research activities.
Originality/value
To the best of the authors’ knowledge, this is the first research that develops performance measures and evaluation plan for low-volume rural freeway CV system under adverse weather conditions. This paper raised some early insights into how CV technology might achieve the goal of improving safety and mobility and has the potential to guide similar research activities conducted by other agencies.
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Joseph J.M. Evers, Léanneke Loeve and David G. Lindeijer
Introduces the concept of service‐oriented agile logistics and presents a generic apparatus for the design of such systems. An analysis of future communication‐based logistics…
Abstract
Introduces the concept of service‐oriented agile logistics and presents a generic apparatus for the design of such systems. An analysis of future communication‐based logistics leads to the logistic control and engineering system SERVICES. The logistic system is conceived as a “society” of interacting “self‐responsible intelligent service‐producing actors”, where services or functions are taken as the system‐base. This means that, instead of working with process‐modules, the development of a service‐oriented information‐system primarily works with service‐modules that program the operational interaction between client, service‐producer and possibly sub‐contracted service‐producers. From this the supporting execution‐control in the context of the service‐producing units can be deduced. A case study of a high‐performance deep‐sea container terminal is given. This shows that the function‐programming system of SERVICES is generic, adequate and effective and that it favours distributed control.
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Eyad Zouher Al-Sibaie, Ali Mohammed Alashwal, Hamzah Abdul-Rahman and Umi Kalsum Zolkafli
Conflict was recognized as a major cause of inefficiency and limited performance of construction projects. Factors pertaining to conflict in construction are vast; however, there…
Abstract
Purpose
Conflict was recognized as a major cause of inefficiency and limited performance of construction projects. Factors pertaining to conflict in construction are vast; however, there have been less recognition of these factors in international construction projects. The purpose of this paper is to provide in-depth understanding of conflict in this context and analyze how it influences project performance.
Design/methodology/approach
A questionnaire survey was used to collect data from 161 professionals working in Malaysian companies, which are undertaking construction projects overseas.
Findings
Analyzing the data using factor analysis revealed six new factors of conflict: external, internal, control-related, knowledge-related, mismanagement, and social conflicts. Further analysis of the data using partial least squares-path modeling (PLS-PM) affirmed a significant relationship between project performance and two factors of conflict only: internal and social. The results also showed that conflict contributes to about 27 percent of the variance in project performance.
Originality/value
This paper provided a clear picture for project managers and team members about specific aspects of conflict and how to mitigate them to attain better performance of international construction projects.
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