Measuring delays for bicycles at signalized intersections using smartphone GPS tracking data

The article describes an application of global positioning system (GPS) tracking data (floating bike data) for measuring delays for cyclists at signalized intersections. For selected intersections, we used trip data collected by smartphone tracking to calculate the average delay for cyclists by interpolation between GPS locations before and after the intersection. The outcomes were proven to be stable for different strategies in selecting the GPS locations used for calculation, although GPS locations too close to the intersection tended to lead to an underestimation of the delay. Therefore, the sample frequency of the GPS tracking data is an important parameter to ensure that suitable GPS locations are available before and after the intersection. The calculated delays are realistic values, compared to the theoretically expected values, which are often applied because of the lack of observed data. For some of the analyzed intersections, however, the calculated delays lay outside of the expected range, possibly because the statistics assumed a random arrival rate of cyclists. This condition may not be met when, for example, bicycles arrive in platoons because of an upstream intersection. This justifies that GPS-based delays can form a valuable addition to the theoretically expected values

A Perspective on NASA Ames Air Traffic Management Research

This paper describes past and present air-traffic-management research at NASA Ames Research Center. The descriptions emerge from the perspective of a technical manager who supervised the majority of this research for the last four years. Past research contributions built a foundation for calculating accurate flight trajectories to enable efficient airspace management in time. That foundation led to two predominant research activities that continue to this day - one in automatically separating aircraft and the other in optimizing traffic flows. Today s national airspace uses many of the applications resulting from research at Ames. These applications include the nationwide deployment of the Traffic Management Advisor, new procedures enabling continuous descent arrivals, cooperation with industry to permit more direct flights to downstream way-points, a surface management system in use by two cargo carriers, and software to evaluate how well flights conform to national traffic management initiatives. The paper concludes with suggestions for prioritized research in the upcoming years. These priorities include: enabling more first-look operational evaluations, improving conflict detection and resolution for climbing or descending aircraft, and focusing additional attention on the underpinning safety critical items such as a reliable datalink

Aircraft Deconfliction Responsibility Across En Route Sectors in NextGen Separation Assurance

The subject of the current research is a Next Generation Air Transportation System (NextGen) concept that involves automated separation assurance developed to enable controllers to provide both safe and efficient air traffic services at much higher traffic densities than possible today. The study investigated the issue of how responsibility should be handled between controllers for the resolution of a conflict that is predicted to occur in a sector other than where it was detected. Two possibilities, a De-Conflicting AirPlanes procedure (DCAP) versus a De-Conflicting AirSpace procedure (DCAS), were examined under human-in-the-loop simulations with scripted aircraft conflicts. Results showed that the DCAS procedure was preferred and that participants experienced less verbal coordination and took less time to resolve conflicts. The results, however, did not reveal significant differences among other plane performance metrics between DCAP and DCAS. These results indicate that the demands of NextGen separation assurance might still be met with ownership and coordination procedures (e.g., DCAP) similar to today. Reducing verbal coordination requirements, however, and allowing separation assurance responsibilities to extend more seamlessly across sector boundaries (e.g., DCAS) would evidently be more acceptable to controllers

Surface Hold Advisor Using Critical Sections

The Surface Hold Advisor Using Critical Sections is a system and method for providing hold advisories to surface controllers to prevent gridlock and resolve crossing and merging conflicts among vehicles traversing a vertex-edge graph representing a surface traffic network on an airport surface. The Advisor performs pair-wise comparisons of current position and projected path of each vehicle with other surface vehicles to detect conflicts, determine critical sections, and provide hold advisories to traffic controllers recommending vehicles stop at entry points to protected zones around identified critical sections. A critical section defines a segment of the vertex-edge graph where vehicles are in crossing or merging or opposite direction gridlock contention. The Advisor detects critical sections without reference to scheduled, projected or required times along assigned vehicle paths, and generates hold advisories to prevent conflicts without requiring network path direction-of-movement rules and without requiring rerouting, rescheduling or other network optimization solutions

A Framework of Point Merge-based Autonomous System for Optimizing Aircraft Scheduling in Busy TMA

International audienceIn this article we present recent work towards the development of an autonomous system with point merge (PM) that performs sequencing, merging and spacing for arrival aircraft in the busy terminal area. This autonomous arrival management system aims to safely solve the major arrival flight scheduling problems currently handled by human controllers. With PM, it has the potential to handle higher traffic demands without more workload on controllers, consequently increasing capacity and reducing delay. The main objective of this paper is to introduce the framework of this autonomous system with PM. Based on analysis of classic PM route structure, a novel PM-based route network is firstly designed for Beijing Capital International Airport. Vertically, this PM system consists of multi-layers on the sequencing legs for different categories of aircraft with Heavy and Medium, horizontally, it is shaped as a lazy “8”. Then, a multiple-objectives function is discussed for this aircraft scheduling problem, operational constraints and conflict detection and resolution are analysed in detail, a modelling strategy with sliding time window and simulated annealing algorithm is proposed for solving this real-time dynamic problem. Experimental results verify our algorithm is well adapting the high-density traffic optimisation, and finally a conclusion is made and future work is pointed ou

Forecast based traffic signal coordination using congestion modelling and real-time data

This dissertation focusses on the implementation of a Real-Time Simulation-Based Signal Coordination module for arterial traffic, as proof of concept for the potential of integrating a new generation of advanced heuristic optimisation tools into Real-Time Traffic Management Systems. The endeavour represents an attempt to address a number of shortcomings observed in most currently marketed on-line signal setting solutions and provide better adaptive signal timings. It is unprecedented in its use of a Genetic Algorithm coupled with Continuous Dynamic Traffic Assignment as solution evaluation method, only made possible by the recently presented parallelisation strategies for the underlying algorithms. Within a fully functional traffic modelling and management framework, the optimiser is developed independently, leaving ample space for future adaptations and extensions, while relying on the best available technology to provide it fast and realistic solution evaluation based on reliable real-time supply and demand data. The optimiser can in fact operate on high quality network models that are well calibrated and always up-to-date with real-world road conditions; rely on robust, multi-source network wide traffic data, rather than being attached to single detectors; manage area coordination using an external simulation engine, rather than a na¨ıve flow propagation model that overlooks crucial traffic dynamics; and even incorporate real-time traffic forecast to account for transient phenomena in the near future to act as a feedback controller. Results clearly confirm the efficacy of the proposed method, by which it is possible to obtain relevant and consistent corridor performance improvements with respect to widely known arterial bandwidth maximisation techniques under a range of different traffic conditions. The computational efforts involved are already manageable for realistic real-world applications, and future extensions of the presented approach to more complex problems seem within reach thanks to the load distribution strategies already envisioned and prepared for in the context of this work