Examination of air transportation trip time variability

Scheduled air transportation is required to provide a service that is safe, consistent, and dependable, with reliable trip times and delays managed within acceptable limits. High trip time variability and delay in the current system are driven by multiple factors; The study objectives were: (1) to develop a comprehensive database for individual major U.S. airline domestic trips between 1995 and 2005; (2) to explore the central tendency and variability of airline gate-to-gate trip times and delays; (3) to develop values for unconstrained, or unimpeded, trip times, and (4) to develop traveler and airline delay and variability costs relative to unimpeded trip times; The research used U.S. Department of Transportation (U.S. DOT) data for scheduled domestic airline trips reported by major U.S. air carriers between 1995 and 2005. For valuing air carrier cost savings, this research estimated variable costs for individual trips, based on individual carrier financial reports to U.S. DOT; The research used reported trip times as a primary indicator, unimpeded trip times as a reference, and attached a cost to the excess of reported trip time over unimpeded trip time at the individual flight level. This approach represents a process for evaluating the time savings and operating cost impacts of measures for increasing capacity and reducing impedance in U.S. domestic scheduled air transportation; Areas in which trip time variability and delay impose a high penalty on travelers and airlines were identified. The most important study results concerned disproportionately higher delays and costs relative to: (1) origin and destination airports and corridors; (2) times of day; and (3) the days with highest delays. The main areas were arrivals and departures at leading airports (40 percent of flights and 55 percent of costs), flight departures and arrivals between noon and early evening (50 percent of flights and 60 percent of costs), and during the 40 percent of days in which there were heavy system wide delays (55 percent of costs) costs appropriate to time changes on individual trips, the magnitude of penalties incurred by impeded trips were estimated relative to unimpeded trips. These were: 150 million annual excess traveler hours per year; {dollar}8 billion annual excess air carrier operating costs; with 400 million annual gallons of excess jet fuel consumption. The costs of impeded trips added about 10 percent (or about {dollar}3.4 billion annually) to airline variable operating costs during the study period

3D-in-2D Displays for ATC.

This paper reports on the efforts and accomplishments of the 3D-in-2D Displays for ATC project at the end of Year 1. We describe the invention of 10 novel 3D/2D visualisations that were mostly implemented in the Augmented Reality ARToolkit. These prototype implementations of visualisation and interaction elements can be viewed on the accompanying video. We have identified six candidate design concepts which we will further research and develop. These designs correspond with the early feasibility studies stage of maturity as defined by the NASA Technology Readiness Level framework. We developed the Combination Display Framework from a review of the literature, and used it for analysing display designs in terms of display technique used and how they are combined. The insights we gained from this framework then guided our inventions and the human-centered innovation process we use to iteratively invent. Our designs are based on an understanding of user work practices. We also developed a simple ATC simulator that we used for rapid experimentation and evaluation of design ideas. We expect that if this project continues, the effort in Year 2 and 3 will be focus on maturing the concepts and employment in a operational laboratory settings

Temporal Logic Motion Planning

In this paper, a critical review on temporal logic motion planning is presented. The review paper aims to address the following problems: (a) In a realistic situation, the motion planning problem is carried out in real-time, in a dynamic, uncertain and ever-changing environment, and (b) The accomplishment of high-level specification tasks which are more than just the traditional planning problem (i.e., start at initial state A and go to the goal state B) are considered. The use of theory of computation and formal methods, tools and techniques present a promising direction of research in solving motion planning problems that are influenced by high-level specification of complex tasks. The review, therefore, focuses only on those papers that use the aforementioned tools and techniques to solve a motion planning problem. A proposed robust platform that deals with the complexity of more expressive temporal logics is also presented.Defence Science Journal, 2010, 60(1), pp.23-38, DOI:http://dx.doi.org/10.14429/dsj.60.9

A fuzzy approach to addressing uncertainty in Airport Ground Movement optimisation

Funded by Engineering and Physical Sciences Research Counci

Travel time variability:Definition and valuation

Increasing traffic leads to increasing severity, spatial extension and duration of congestion. Congestion has two immediate consequences. One is that travel times increase on average. Another is that travel times become increasingly variable and unpredictable. When performing economic appraisal of transport policies it is important to account for both. This is fast becoming widely acknowledged in many countries around the world. The subject is, however, quite difficult for several reasons and so far there is no established consensus on how to define and value travel time variability. This report was commissioned by the Danish Ministry of Transport and its agencies Vejdirektoratet (the Road Directorate) and Trafikstyrelsen (the Rail Agency). Its purpose is to establish a definition of travel time variability and its value that is theoretically sound, possible to estimate from individual preferences, and applicable with existing or realistically foreseeable traffic models. In addition, the report provides short term recommenda- tions for including valuation of travel time variability in Danish practice for economic appraisal of transport projects and outlines a future Danish study of the valuation of travel time variability

Ant Colony Optimisation for Dynamic and Dynamic Multi-objective Railway Rescheduling Problems

Recovering the timetable after a delay is essential to the smooth and efficient operation of the railways for both passengers and railway operators. Most current railway rescheduling research concentrates on static problems where all delays are known about in advance. However, due to the unpredictable nature of the railway system, it is possible that further unforeseen incidents could occur while the trains are running to the new rescheduled timetable. This will change the problem, making it a dynamic problem that changes over time. The aim of this work is to investigate the application of ant colony optimisation (ACO) to dynamic and dynamic multiobjective railway rescheduling problems. ACO is a promising approach for dynamic combinatorial optimisation problems as its inbuilt mechanisms allow it to adapt to the new environment while retaining potentially useful information from the previous environment. In addition, ACO is able to handle multi-objective problems by the addition of multiple colonies and/or multiple pheromone and heuristic matrices. The contributions of this work are the development of a junction simulator to model unique dynamic and multi-objective railway rescheduling problems and an investigation into the application of ACO algorithms to solve those problems. A further contribution is the development of a unique two-colony ACO framework to solve the separate problems of platform reallocation and train resequencing at a UK railway station in dynamic delay scenarios. Results showed that ACO can be e ectively applied to the rescheduling of trains in both dynamic and dynamic multi-objective rescheduling problems. In the dynamic junction rescheduling problem ACO outperformed First Come First Served (FCFS), while in the dynamic multi-objective rescheduling problem ACO outperformed FCFS and Non-dominated Sorting Genetic Algorithm II (NSGA-II), a stateof- the-art multi-objective algorithm. When considering platform reallocation and rescheduling in dynamic environments, ACO outperformed Variable Neighbourhood Search (VNS), Tabu Search (TS) and running with no rescheduling algorithm. These results suggest that ACO shows promise for the rescheduling of trains in both dynamic and dynamic multi-objective environments.Engineering and Physical Sciences Research Council (EPSRC

Improving regional passenger rail services

This report reviews the options available for upgrading existing passenger train services, drawing from local and international case studies to inform the conclusions. These case studies illustrate both the range of upgrades available and their effectiveness in increasing rail patronage and mode share. Travellers seek a comfortable, accessible and dependable service with low transit and waiting times which means, for the train provider, delivering reliable, frequent and fast services. These features lie at the heart of upgrades. There is no rule-of-thumb "best" upgrade option: the effectiveness, scope and cost of improvements of each of the service attributes varies between projects, locations and also the travel markets and competing mode attributes

Complexity in organisations: a conceptual model: executive summary

Industrial organisations face uncertainty created by consumers, suppliers, competitors and other environmental factors. To deal with this uncertainty, managers have to coordinate the resources of the organisation to produce a variety of behaviours that can cope with environmental change. An organisation that does not have sufficient internal complexity to adapt to the environment cannot survive, while, an organisation with excessive complexity would waste resources and might lose its ability to react to the environment. The main objective of the research was to create a model for dealing with complexity and uncertainty in organisations. The initial ideas for the model originated from the literature, particularly in the fields of systems and complexity theory. These initial ideas were developed through a series of five case studies with four companies, namely British Airways, British Midlands International (BMI), HS Marston and the Ford Motor Company. Each case study contributed to the development of the model, as well as providing immediate benefits for the organisations involved. The first three case studies were used in the development of the model, by analysing the way managers made decisions in situations of complexity and uncertainty. For the final two case studies, the model was already developed and it was possible to apply it, using these cases as a means of validation. A summary of the case studies is presented here, highlighting their contributions to the creation and testing of the model. The main innovation of the research was the creation and application of the Complexity-Uncertainty model, a descriptive framework that classifies generic strategies for dealing with complexity and uncertainty in organisations. The model considers five generic strategies: automation, simplification, planning, control and self-organisation, and indicates when each of these strategies can be more effective according to the complexity and uncertainty of the situation. This model can be used as a learning tool to help managers in industry to conceptualise the nature of complexity in their organisation, in relation to the uncertainty in the environment. The model shows managers the range of strategic options that are available under a particular situation, and highlights the benefits and limitations of each of these strategic options. This is intended to help managers make better decisions based on a more holistic understanding of the organisation, its environment and the strategies available