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Antoniou C.,National Technical University of Athens | Balakrishna R.,Caliper Corporation | Koutsopoulos H.N.,KTH Royal Institute of Technology
European Transport Research Review

Purpose: The objective of this research is to provide an overview of emerging data collection technologies and their impact on traffic management applications. Methods: Several existing and emerging surveillance technologies are being used for traffic data collection. Each of these technologies has different technical characteristics and operating principles, which determine the types of data collected, accuracy of the measurements, levels of maturity, feasibility and cost, and network coverage. This paper reviews the different sources of traffic surveillance data currently employed, and the types of traffic management applications they may support. Results: Automated Vehicle Identification data have several applications in traffic management and many more are certain to emerge as these data become more widely available, reliable, and accessible. Representative examples in this field are presented. Furthermore, the fusion of condition information with traffic data can result in better and more responsive dynamic traffic management applications with a richer data background. Conclusions: The current state-of-the-art of traffic modeling is discussed, in the context of using emerging data sources for better planning, operations and dynamic management of road networks. © 2011 The Author(s). Source

Ben-Akiva M.E.,Massachusetts Institute of Technology | Gao S.,University of Massachusetts Amherst | Wei Z.,Caliper Corporation | Wen Y.,Google
Transportation Research Part C: Emerging Technologies

The management of severe congestion in complex urban networks calls for dynamic traffic assignment (DTA) models that can replicate real traffic situations with long queues and spillbacks. DynaMIT-P, a mesoscopic traffic simulation system, was enhanced and calibrated to capture the traffic characteristics in a sub-area of Beijing, China. The network had 1698 nodes and 3180 directed links in an area of around 18 square miles. There were 2927 non-zero origin-destination (OD) pairs and around 630,000 vehicles were simulated over 4. h of the morning peak. All demand and supply parameters were calibrated simultaneously using sensor counts and floating car travel time data. Successful calibration was achieved with the Path-size Logit route choice model, which accounted for overlapping routes. Furthermore, explicit representations of lane groups were required to properly model traffic delays and queues. A modified treatment of acceptance capacity was required to model the large number of short links in the transportation network (close to the length of one vehicle). In addition, even though bicycles and pedestrians were not explicitly modeled, their impacts on auto traffic were captured by dynamic road segment capacities. © 2012 Elsevier Ltd. Source

Antoniou C.,National Technical University of Athens | Balakrishna R.,Caliper Corporation | Koutsopoulos H.N.,KTH Royal Institute of Technology | Ben-Akiva M.,Massachusetts Institute of Technology
International Journal of Modelling and Simulation

Dynamic Traffic Assignment (DTA) integrates complex transportation demand and network supply simulation models to estimate prevailing traffic conditions, predict future network performance and generate consistent, anticipatory route guidance. Prior to deployment, the DTA's parameters and inputs must be calibrated to accurately reflect travel behaviour and traffic dynamics. This paper presents a unified framework for off-line and on-line DTA calibration. Off-line calibration simultaneously estimates demand and supply model parameters. On-line calibration jointly updates - in real-time - the off-line estimates in order to more accurately capture current conditions. The developed methods are flexible and can be applied to any simulation model and may utilize any available traffic surveillance information (including Automated Vehicle Identification systems, probe vehicles and other emerging data sources). The off-line and on-line components complement each other to efficiently combine historical and real-time information. The calibration approaches are demonstrated with DynaMIT (Dynamic network assignment for the Management of Information to Travelers), using time-varying count, speed and density data from conventional traffic sensors. Source

Caliper Corporation | Date: 2007-10-17


Caliper Corporation | Date: 2009-03-24

Printed test forms and sheets in the field of occupational aptitude. Testing to determine job and professional aptitude.

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