| 1. |
- Allström, Andreas, 1978-, et al.
(author)
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Evaluation of travel time estimation based on LWR-v and CTM-v : A case study in Stockholm
- 2012
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In: 15th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2012. - Piscataway, N.J, USA : IEEE. - 9781467330640 - 9781467330626 ; , s. 1644-1649
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Conference paper (peer-reviewed)abstract
- Real-time estimations of current and future traffic states are an essential part of traffic management and traffic information systems. Within the Mobile Millennium project considerable effort has been invested in the research and development of a real-time estimation system that can fuse several sources of data collected in California. During the past year this system has been adapted to also handle traffic data collected in Stockholm. This paper provides an overview of the model used for highways and presents results from an initial evaluation of the system. As part of the evaluation process, GPS data collected in an earlier field-test and estimations generated by the existing system used by the TMC in Stockholm, are compared with the estimations generated by the Mobile Millennium system. Given that the Mobile Millennium Stockholm system has not undergone any calibration, the results from the evaluation are considered promising. The estimated travel times correspond well to those measured in the field test. Furthermore, the estimations generated by the Mobile Millennium system can be regarded as superior to those of existing traffic management system in Stockholm. The highway model was found to perform well even with a reduction in the number of sensors providing data. The findings of this study indicate the robustness of the Mobile Millennium system and demonstrate how the system can be migrated to other geographical areas with similar sources of available data.
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| 2. |
- Fadaei, Masoud, et al.
(author)
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Estimating flexible route choice models using sparse data
- 2012
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In: Intelligent Transportation Systems (ITSC), 2012 15th International IEEE Conference on. - : IEEE conference proceedings. - 9781467330640 ; , s. 1215-1220
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Conference paper (peer-reviewed)abstract
- GPS and nomad devices are increasingly used to provide data from individuals in urban traffic networks. In many different applications, it is important to predict the continuation of an observed path, and also, given sparse data, predict where the individual (or vehicle) has been. Estimating the perceived cost functions is a difficult statistical estimation problem, for different reasons. First, the choice set is typically very large. Second, it may be important to take into account the correlation between the (generalized) costs of different routes, and thus allow for realistic substitution patterns. Third, due to technical or privacy considerations, the data may be temporally and spatially sparse, with only partially observed paths. Finally, the position of vehicles may have measurement errors. We address all these problems using a indirect inference approach. We demonstrate the feasibility of the proposed estimator in a model with random link costs, allowing for a natural correlation structure across paths, where the full choice set is considered.
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| 3. |
- Gray, A, et al.
(author)
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Integrated threat assessment and control design for roadway departure avoidance
- 2012
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In: 2012 15th International IEEE Conference on Intelligent Transportation Systems, ITSC 2012, Anchorage, AK, 16 - 19 September 2012. - 9781467330640 ; , s. 1714-1719
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Conference paper (peer-reviewed)abstract
- This paper presents the design of an active safety system for prevention of unintended roadway departures. In normal driving conditions, the driver fully commands the vehicle while the safety system corrects the driver's steering and braking action in case there's a risk that the vehicle unintentionally departs the road. A model of the driver's nominal behavior is first estimated based on his or her observed behavior. A nonlinear model of the vehicle in closed loop with the driver is then used to reformulate the threat assessment and control problems as a combined optimization problem. The resulting predictive controller is always active and mode switching is not necessary. Experimental data collected using human drivers in a driver simulator demonstrate the capability of the suggested controller to detect and avoid roadway departures while avoiding unnecessary interventions.
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| 4. |
- Jonsson, Magnus, 1969-, et al.
(author)
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Increasing the probability of timely and correct message delivery in road side unit based vehicular communication
- 2012
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In: IEEE Conference Intelligent Transportation Systems (ITSC), 2012 15th International Conference. - Piscataway : IEEE Press. - 9781467330626 - 9781467330640 ; , s. 672-679
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Conference paper (peer-reviewed)abstract
- Intelligent transport systems provide a multitude of possibilities when it comes to increasing traffic safety on our roads. Many of the proactive traffic safety applications under development today demand timely and reliable treatment of deadline dependent data traffic. Unfortunately it is not possible to provide any timing guarantees when using the current IEEE 802.11p standard for wireless access in vehicular environments. Additionally, a difficult wireless channel environment makes successful data transmissions very challenging. We suggest adding a real-time layer, comprising a deterministic medium access control protocol and transport layer retransmissions, on top of IEEE 802.11p in order to enable guaranteed real-time behaviour and to improve reliability. In a simulation study we show that the packet error rate can be decreased by several orders of magnitude while being able to guarantee timely treatment of both ordinary transmissions and retransmissions by the help of a real-time schedulability analysis.
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| 5. |
- Rahmani, Mahmood, et al.
(author)
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Path inference of low-frequency GPS probes for urban networks
- 2012
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In: Intelligent Transportation Systems (ITSC), 2012 15th International IEEE Conference on. - : IEEE. - 9781467330640 ; , s. 1698-1701
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Conference paper (peer-reviewed)abstract
- The use of probe vehicles in traffic management is growing rapidly. The reason is that the required data collection infrastructure is increasingly in place in urban areas with significant number of mobile sensors moving around covering expansive areas of the road network. The data is usually sparse in time and location. It usually includes only geo-location and timestamp. Extracting the paths taken by the vehicles is an important step in using this data. Such methods are referred to as map-matching or path inference. This paper introduces a path inference method for low-frequency probes and evaluates its accuracy in comparison to a recent method.
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| 6. |
- Solyom, Stefan, 1975, et al.
(author)
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Performance limitations in vehicle platoon control
- 2012
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In: 2012 15th International IEEE Conference on Intelligent Transportation Systems, ITSC 2012, Anchorage, AK, 16 - 19 September 2012. - 9781467330640 ; , s. 1-6
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Conference paper (peer-reviewed)abstract
- One of the major benefits of driving vehicles in controlled, close formations such as platoons is that of reduced air drag. However, this will set hard performance requirements on the system actuators, sensors and controllers of each vehicle. This paper analyzes the effects of fundamental limitations on the longitudinal and lateral control performance of a platoon and the effects on following distance, perceived safety and fuel economy. The trade-off between minimizing fuel consumption and maintaining a safe following distance is analyzed and described. The analysis is based on fundamental properties of linear systems such as Bode's phase area relation. Design guidelines are proposed and results from vehicle testing are presented.
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| 7. |
- Trigueiro Baptista, Arthur, et al.
(author)
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Towards an uncertainty aware short-term travel time prediction using GPS bus data : Case study in Dublin
- 2012
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In: Intelligent Transportation Systems (ITSC), 2012 15th International IEEE Conference on. - : IEEE. - 9781467330640 ; , s. 1620-1625
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Conference paper (peer-reviewed)abstract
- In this paper we propose and study the performances of a bus travel times prediction model using real bus location data from the city of Dublin. The proposed prediction model uses a modified version of the K-Nearest Neighbors algorithm, KNN, algorithm and exhibits a significant improvement over the baseline KNN. We also investigate the benefits of decomposing travel times in three components: running time, dwell time at bus stops and time stopped at traffic lights. We discuss that most of the uncertainty on the travel times comes from time spent at bus stops and traffic lights, and prediction of running time only is much improved due to the reduced uncertainty at bus stops and traffic lights. Finally we show the need of a prediction algorithm for time spent at bus stops and traffic lights that added to the prediction of running time would allow for an uncertainty aware travel time predictor.
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