| 1. |
- Antoniou, Constantinos, et al.
(författare)
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Dynamic Traffic Demand Prediction Using Conventional and Emerging Data Sources
- 2006
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Ingår i: IEE Proceedings Intelligent Transport Systems. - : Institution of Engineering and Technology (IET). - 1748-0248. ; 153:1, s. 97-104
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Tidskriftsartikel (refereegranskat)abstract
- Origin-destination (OD) flow estimation and prediction is an important problem with applications in Dynamic Traffic Management, and traffic estimation and prediction systems. Recent developments in traffic data collection technologies provide data that have not yet been used in OD estimation and prediction. In this paper, a new, flexible, and general methodology for OD estimation and prediction is presented. The methodology can incorporate any available information from conventional and emerging traffic data collection technologies (such as automatic vehicle identification systems and probe vehicles). The application of the methodology is presented through a case study. The results support the importance of incorporating additional data in the OD estimation problem. An overall improvement for estimation and one-step prediction exceeds 45 when point-to-point information is added to the model (over the base case when only point link flows are available), while an improvement of more than 35 is maintained even for four-step prediction (i.e. 1 h into the future).
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| 2. |
- Antoniou, Constantinos, et al.
(författare)
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Estimation of Traffic Dynamics Models with Machine Learning Methods
- 2006
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Ingår i: Transportation Research Record. - 0361-1981 .- 2169-4052. ; 1965, s. 103-111
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Tidskriftsartikel (refereegranskat)abstract
- Speed-density relationships are a classic way of modeling stationary traffic relationships. Besides offering valuable insight into traffic stream flows, such relationships are widely used in dynamic traffic assignment (DTA) systems. In this research, an alternative paradigm for traffic dynamics models, appropriate for traffic simulation models and based on machine-learning approaches such as k-means clustering, k-nearest-neighborhood classification, and locally weighted regression is proposed. Although these models may not provide as much insight into traffic flow theory as speed-density relationships do, they allow for easy incorporation of additional information to speed estimation and hence may be more appropriate for use in DTA models, especially simulation-based models. This paper (with data from a network in Irvine, California) demonstrates that such machine-learning methods can considerably improve the accuracy of speed estimation.
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| 3. |
- Antoniou, Constantinos, et al.
(författare)
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Evaluation of diversion strategies using dynamic traffic assignment
- 2011
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Ingår i: Transportation planning and technology (Print). - : Informa UK Limited. - 0308-1060 .- 1029-0354. ; 34:3, s. 199-216
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Tidskriftsartikel (refereegranskat)abstract
- A framework for the evaluation of the effectiveness of traffic diversion strategies for non-recurrent congestion, based on predictive guidance and using dynamic traffic assignment, is presented. Predictive guidance is based on a short-term prediction of traffic conditions, incorporating user reaction to information and guidance. A case study of the Lower Westchester County network in New York State, using DynaMIT-P, is presented to illustrate the application of the framework. DynaMIT-P is capable of evaluating diversion strategies based on predicted conditions, which take into account drivers' response to traffic information. The case study simulates the operations of predictive variable message signs positioned in strategic locations. DynaMIT-P is calibrated for the study network and used to establish base conditions for two incident scenarios in the absence of advanced traveller information systems. The effectiveness of predictive diversion strategies is evaluated (using rigorous statistical tests) by comparing traffic conditions with and without diversion strategies. The empirical findings suggest that incident diversion strategies based on predictive guidance result in travel time savings and increased travel time reliability.
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| 4. |
- Antoniou, Constantinos, et al.
(författare)
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Non–linear Kalman Filtering Algorithms for On–line Calibration of Dynamic Traffic Assignment Models
- 2007
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - 1524-9050 .- 1558-0016. ; 8:4, s. 661-670
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Tidskriftsartikel (refereegranskat)abstract
- An online calibration approach that jointly estimates demand and supply parameters of dynamic traffic assignment (DTA) systems is presented and empirically validated through an extensive application. The problem can be formulated as a nonlinear state-space model. Because of its nonlinear nature, the resulting model cannot be solved by the Kalman filter, and therefore, nonlinear extensions need to be considered. The following three extensions to the Kalman filtering algorithm are presented: 1) the extended Kalman filter (EKF); 2) the limiting EKF (LimEKF); and 3) the unscented Kalman filter. The solution algorithms are applied to the on-line calibration of the state-of-the-art DynaMIT DTA model, and their use is demonstrated in a freeway network in Southampton, U.K. The LimEKF shows accuracy that is comparable to that of the best algorithm but with vastly superior computational performance. The robustness of the approach to varying weather conditions is demonstrated, and practical aspects are discussed.
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| 5. |
- Antoniou, Constantinos, et al.
(författare)
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On-line Calibration of Traffic Prediction Models
- 2005
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Ingår i: Transportation Research Record. - 0361-1981 .- 2169-4052. ; 1934, s. 235-245
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Tidskriftsartikel (refereegranskat)abstract
- A methodology for the on-line calibration of the speed-density relationship is formulated as a flexible state-space model. Applicable solution approaches are discussed and three of them (extended Kalman filter (EKF), iterated EKF, and unscented Kalman filter (UKF) are selected and presented in detail. An application of the methodology with freeway sensor data from two networks in Europe and the U.S. is presented. The improvement in the estimation and prediction of speeds due to on-line calibration (compared with the speeds obtained from the off-line calibrated relationship) is demonstrated. The EKF provides the most straightforward solution to this problem, and indeed achieves considerable improvements in estimation and prediction accuracy. The benefits obtained from the -more computationally expensive-iterated EKF algorithm are shown. An innovative solution technique (the UKF) is also presented. The UKF has a number of unique qualities and advantages over the EKF, including no assumption of analytical representation of the model and no need for explicit computation of derivatives. Empirical results suggest that the UKF outperforms the other two solution techniques in prediction accuracy.
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| 6. |
- Balakrishna, Ramachandran, et al.
(författare)
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A Simulation-based Evaluation of Advanced Traveler Information Systems
- 2005
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Ingår i: Transportation Research Record. - : Transportation Research Board of the National Academies. - 0361-1981 .- 2169-4052. ; 1910, s. 90-98
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Tidskriftsartikel (refereegranskat)abstract
- Traveler information has the potential to reduce travel times and improve their reliability. Studies have verified that driver overreaction from the dissemination of information can be eliminated through prediction-based route guidance that uses short-term forecasts of network state. Critical off-line tests of advanced dynamic traffic assignment-based prediction systems have been limited, since the system being evaluated has also been used as the test bed. This paper outlines a detailed simulation-based laboratory for the objective and independent evaluation of advanced traveler information systems, a laboratory with the flexibility to analyze the impacts of various design parameters and modeling errors on the quality of the generated guidance. MITSIMLab, a system for the evaluation of advanced traffic management systems, is integrated with Dynamic Network Assignment for the Management of Information to Travelers (DynaMIT), a simulation-based decision support system designed to generate prediction-based route guidance. Evaluation criteria and requirements for the closed-loop integration of MITSIMLab and DynaMIT are discussed. Detailed case studies demonstrating the evaluation methodology and sensitivity of DynaMIT's guidance are presented.
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| 7. |
- Balakrishna, R., et al.
(författare)
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Calibration of Microscopic Traffic Simulation Models : Methods and Application
- 2007
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :1999, s. 198-207
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Tidskriftsartikel (refereegranskat)abstract
- A mathematical framework and a solution approach are presented for the simultaneous calibration of the demand and supply parameters and inputs to microscopic traffic simulation models as well as a large-scale application emphasizing practical issues. Microscopic traffic simulation models provide detailed estimates of evolving network conditions by modeling time-varying demand patterns and individual drivers' detailed behavioral decisions. Such models are composed of elements that simulate different demand and supply processes and their complex interactions. Several model inputs (such as origin-destination flows) and parameters (car-following and lane-changing coefficients) must be specified before these simulation tools can be applied, and their values must be determined so that the simulation output accurately replicates the reality reflected in traffic measurements. A methodology is presented here for simultaneously estimating all microscopic simulation model parameters by using general traffic measurements. A large-scale case study for the calibration of the MITSimLab microscopic traffic simulation model by using the network of Lower Westchester County, New York, is employed to demonstrate the feasibility, application, and benefits of the proposed methodology.
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| 8. |
- Balakrishna, Ramachandran, et al.
(författare)
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Incorporating Within-Day Transitions in Simultaneous Offline Estimation of Dynamic Origin-Destination Flows Without Assignment Matrices
- 2008
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2085, s. 31-38
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Tidskriftsartikel (refereegranskat)abstract
- An offline methodology is presented: it simultaneously estimates dynamic origin-destination (O-D) matrices, without using assignment matrices that incorporate within-day transition equations. The proposed formulation and solution approach extends a calibration method recently developed that directly uses the output of any network loading model (such as a dynamic traffic assignment or simulation model) so that the complex relationships between O-D flows and model outputs are accurately captured (as opposed to the more common method of approximate linear relationships based oil file assignment matrix). The study extends the original formulation by incorporating spatial and temporal relationships among various O-D flows (transition equations). These transition equations link O-D flow variables across time intervals in such it way that known structural demand patterns can be preserved in the new estimates. Such transition equations, although common in the context of real-time O-D flows, complicate the offline simultaneous estimation of O-D flows and have not been used to their full potential in the past. The approach is demonstrated through a case study.
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| 9. |
- Balakrishna, Ramachandran, et al.
(författare)
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Offline calibration of dynamic traffic assignment : Simultaneous Demand-and-Supply Estimation
- 2007
-
Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2003, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Advances in intelligent transportation systems have resulted in deployment of surveillance systems that automatically collect and store extensive networkwide traffic data. Dynamic traffic assignment (DTA) models have been developed for a variety of dynamic traffic management applications. They are designed to estimate and predict the evolution of congestion with detailed models and algorithms that capture travel demand and network supply and their complex interactions. The availability of rich time-varying traffic data spanning multiple days provides the opportunity to calibrate a DTA model’s inputs and parameters offline so that its outputs reflect field conditions in future offline and online real-time applications. The state of the art of DTA model calibration is a sequential approach, with supply model calibration (assuming known demand inputs) followed by demand calibration with fixed supply parameters. An offline DTA model calibration methodology is presented for simultaneous estimation of all demand-and-supply inputs and parameters, with sensor data. A minimization formulation that can use any general traffic data and present scalable solution approaches for the complex, nonlinear, stochastic optimization problem is adopted. A case study with DynaMIT, a DTA model with traffic estimation and prediction capabilities, is used to demonstrate and validate the methodology. Archived sensor data and a network from Los Angeles, California, are used to demonstrate scalability. Results indicate that the simultaneous approach significantly outperforms the sequential state of the art in terms of modeling accuracy and computational efficiency.
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| 10. |
- Balakrishna, R., et al.
(författare)
-
Time-dependent origin-destination estimation without assignment matrices
- 2019
-
Ingår i: Transport Simulation: Beyond Traditional Approaches. - : Taylor & Francis Group. ; , s. 201-213
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Time-dependent origin-destination (OD) flows are crucial inputs to dynamic traffic assignment (DTA) models. However, they are often unobserved, and must be estimated from indirect traffic measurements collected from the study network. Approaches to estimate OD flows from link counts traditionally rely on assignment matrices that map the OD flow variables onto the counts. However, this method (a) approximates the complex relationship between OD flows and counts with a linear function, (b) is restricted to the use of only counts, and cannot exploit richer data such as speeds, densities or travel times, and (c) cannot estimate route choice and supply parameters that critically impact the OD estimates. This chapter presents a dynamic OD estimation method that is accurate and flexible in the use of general traffic data. Moreover, it simultaneously estimates all parameters with an impact on OD estimation, and can be applied to any traffic assignment model.
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| 11. |
- Ben-Akiva, M., et al.
(författare)
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Towards Disaggregate Dynamic Travel Forecasting Models
- 2007
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Ingår i: Tsinghua Science and Technology. - 1007-0214. ; 12:2, s. 115-130
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Tidskriftsartikel (refereegranskat)abstract
- The authors argue that travel forecasting models should be dynamic and disaggregate in their representation of demand, supply, and supply-demand interactions, and propose a framework for such models. The proposed framework consists of disaggregate activity-based representation of travel choices of individual motorists on the demand side integrated with disaggregate dynamic modeling of network performance, through vehicle-based traffic simulation models on the supply side. The demand model generates individual members of the population and assigns to them socioeconomic characteristics. The generated motorists maintain these characteristics when they are loaded on the network by the supply model. In an equilibrium setting, the framework lends itself to a fixed-point formulation to represent and resolve demand-supply interactions. The paper discusses some of the remaining development challenges and presents an example of an existing travel forecasting model system that incorporates many of the proposed elements.
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| 12. |
- Burghout, Wilco, et al.
(författare)
-
Hybrid Mesoscopic-Microscopic Traffic Simulation
- 2005
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Ingår i: Transportation Research Record. - 0361-1981 .- 2169-4052. ; 1934, s. 218-225
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Tidskriftsartikel (refereegranskat)abstract
- Traffic simulation is an important tool for modeling the operations of dynamic traffic systems. Although microscopic simulation models provide a detailed representation of the traffic process, macroscopic and mesoscopic models capture the traffic dynamics of large networks in less detail but without the problems of application and calibration of microscopic models. This paper presents a hybrid mesoscopic-microscopic model that applies microscopic simulation to areas of specific interest while simulating a large surrounding network in less detail with a mesoscopic model. The requirements that are important for a hybrid model to be consistent across the models at different levels of detail are identified. These requirements vary from the network and route choice consistency to the consistency of the traffic dynamics at the boundaries of the microscopic and mesoscopic submodels. An integration framework that satisfies these requirements is proposed. A prototype hybrid model is used to demonstrate the application of the integration framework and the solution of the various integration issues. The hybrid model integrates MlTSIMLab, a microscopic traffic simulation model, and Mezzo, a newly developed mesoscopic model. The hybrid model is applied in two case studies. The results are promising and support both the proposed architecture and the importance of integrating microscopic and mesoscopic models.
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| 13. |
- Burghout, Wilco, et al.
(författare)
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Incident Management and Traffic Information Tools and Methods for Simulation-Based Traffic Prediction
- 2010
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2161, s. 20-28
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Tidskriftsartikel (refereegranskat)abstract
- Incident response and mitigation are among the main tasks of operators at traffic control centers. Simulation models have a good chance of reproducing and predicting the effects of incident response by explicitly modeling driver response to the incident and information provided. In the PREDIKT project sponsored by the Swedish National Road Administration, the state-of-the-art mesoscopic simulation model MEZZO was extended to provide decision support for incident management. Numerous essential modeling components are described and tested, including modeling the incident response logic, a mixed-logit model, and a method for generating alternatives for drivers switching routes. In addition, the results of a fast calibration method based on simultaneous perturbation statistic approximation are presented. The model components are tested in a small case study that investigates the effect of delay in providing information to drivers after incidents. A linearization of speed-density functions also is shown to improve computational performance by 30% and increase calibration speed and stability while preserving simulation accuracy.
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| 14. |
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| 15. |
- Farah, Haneen, et al.
(författare)
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Do cooperative systems make drivers' car-following behavior safer?
- 2014
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Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 41, s. 61-72
-
Tidskriftsartikel (refereegranskat)abstract
- The main goal of in-vehicle technologies and co-operative services is to reduce congestion and increase traffic safety. This is achieved by alerting drivers on risky traffic conditions ahead of them and by exchanging traffic and safety related information for the particular road segment with nearby vehicles. Road capacity, level of service, safety, and air pollution are impacted to a large extent by car-following behavior of drivers. Car-following behavior is an essential component of micro-simulation models. This paper investigates the impact of an infrastructure-to-vehicle (I2V) co-operative system on drivers' car-following behavior. Test drivers in this experiment drove an instrumented vehicle with and without the system. Collected trajectory data of the subject vehicle and the vehicle in front, as well as socio-demographic characteristics of the test drivers were used to estimate car-following models capturing their driving behavior with and without the I2V system. The results show that the co-operative system harmonized the behavior of drivers and reduced the range of acceleration and deceleration differences among them. The observed impact of the system was largest on the older group of drivers.
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| 16. |
- Fu, Jiali, et al.
(författare)
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Identification of workstations in earthwork operations from vehicle GPS data
- 2017
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Ingår i: Automation in Construction. - : ELSEVIER SCIENCE BV. - 0926-5805 .- 1872-7891. ; 83, s. 237-246
-
Tidskriftsartikel (refereegranskat)abstract
- The paper proposes a methodology for the identification of workstations in earthwork operations based on GPS traces from construction vehicles. The model incorporates relevant information extracted from the GPS data to infer locations of different workstations as probability distributions over the environment. Monitoring of workstation locations may support map inference for generating and continuously updating the layout and road network topology of the construction environment. A case study is conducted at a complex earthwork site in Sweden. The workstation identification methodology is used to infer the locations of loading stations based on vehicle speeds and interactions between vehicles, and the locations of dumping stations based on vehicle turning patterns. The results show that the proposed method is able to identify workstations in the earthwork environment efficiently and in sufficient detail.
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| 17. |
- Fu, Jiali, et al.
(författare)
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Optimizing fleet selection for earthmoving operations
- 2013
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Ingår i: ISEC 2013 - 7th International Structural Engineering and Construction Conference. - : Research Publishing Services. - 9810753551 - 9789810753559 ; , s. 1261-1266
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Konferensbidrag (refereegranskat)abstract
- Earthmoving operations often involve a large number of specially designed equipment with significant purchasing/leasing prices, high operating and maintenance costs. Hence, choosing the right fleet is a major concern from the construction planners' point of view. This paper presents a methodology that combines discrete-event simulation and optimization to solve the optimal fleet selection problem for earthmoving operations. Two optimization objectives are formulated and solved using the proposed framework and a genetic algorithm: minimization of Total Cost of Ownership (TCO) and maximization of productivity. Further, a two-stage rating scheme is introduced to arrange the fleet configurations so that the optimization algorithm converges to a fleet with better second-stage performance while the first-stage performance remains at the same level. The case study shows that the proposed mechanism can effectively allocate a local optimal equipment combination for earthmoving operations and hence serve as an efficient tool for construction management.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Jenelius, Erik, et al.
(författare)
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Travel time estimation for urban road networks using low frequency probe vehicle data
- 2013
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Ingår i: Transportation Research Part B. - : Elsevier BV. - 0191-2615 .- 1879-2367. ; 53, s. 64-81
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a statistical model for urban road network travel time estimation using vehicle trajectories obtained from low frequency GPS probes as observations, where the vehicles typically cover multiple network links between reports. The network model separates trip travel times into link travel times and intersection delays and allows correlation between travel times on different network links based on a spatial moving average (SMA) structure. The observation model presents a way to estimate the parameters of the network model, including the correlation structure, through low frequency sampling of vehicle traces. Link-specific effects are combined with link attributes (speed limit, functional class, etc.) and trip conditions (day of week, season, weather, etc.) as explanatory variables. The approach captures the underlying factors behind spatial and temporal variations in speeds, which is useful for traffic management, planning and forecasting. The model is estimated using maximum likelihood. The model is applied in a case study for the network of Stockholm, Sweden. Link attributes and trip conditions (including recent snowfall) have significant effects on travel times and there is significant positive correlation between segments. The case study highlights the potential of using sparse probe vehicle data for monitoring the performance of the urban transport system.
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| 23. |
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| 24. |
- Kazagli, Evanthia, et al.
(författare)
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Estimation of Arterial Travel Time from Automatic Number Plate Recognition Data
- 2013
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2391, s. 22-31
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Tidskriftsartikel (refereegranskat)abstract
- Automatic vehicle identification (AVI) systems are increasingly used for the collection of traffic data in urban and freeway networks. Several methods have been proposed for the estimation of travel times from AVI data, mainly for freeways. The problem of estimation of travel times in urban networks was examined. The main difference between freeway and urban networks is that urban network AVI data are often extremely noisy. A major part of that noise is attributed to vehicles that do not traverse the monitored section directly but stop for various reasons. A mixture model was proposed to capture the underlying states of the measurements of AVI travel times in urban areas. The hypothesis was that travel times are drawn from two (or more) populations, one representing normal movement through the network and one representing vehicles that stop for whatever reason. The method was applied with AVI data (collected through a system for automatic recognition of number plates) from a number of corridors in central Stockholm, Sweden. The model was estimated as a mixture-of two lognormal distributions, and bootstrap standard errors were calculated. The results illustrate the robustness of the method and its ability to identify the underlying distribution of the latent populations consistent with the characteristics of each route, while standard methods for outlier removal fail.
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| 25. |
- Koutsopoulos, Haris N., et al.
(författare)
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Latent Class Model for Car Following Behavior
- 2012
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Ingår i: Transportation Research Part B. - : Elsevier BV. - 0191-2615 .- 1879-2367. ; 46:5, s. 563-578
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Tidskriftsartikel (refereegranskat)abstract
- Car-following behavior, which describes the behavior of a vehicle while following the vehicle in front of it, has a significant impact on traffic performance, safety, and air pollution. In addition, car-following is an essential component of micro-simulation models. Over the last decade the use of microscopic simulation models as a tool for investigating traffic systems, ITS applications, and emission impacts, is becoming increasingly popular. The paper presents a flexible framework for modeling car-following behavior that relaxes some limitations and assumptions of the most commonly used car following models. The proposed approach recognizes different regimes in driving such as car-following, free-flow, emergency stopping, and incorporates different decisions in each regime, such as acceleration, deceleration, and do-nothing depending on the situation. A case study using NGSIM vehicle trajectory data is used to illustrate the proposed model structure. Statistical tests suggest that the model performs better than previous models.
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| 26. |
- Koutsopoulos, Haris N., et al.
(författare)
-
Preface
- 2011
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Ingår i: Procedia - Social and Behavioral Sciences. - : Elsevier Ltd. - 1877-0428. ; 16, s. 1-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 27. |
- Koutsopoulos, Haris N., et al.
(författare)
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Simulation of Urban Rail Operations : Application Framework
- 2007
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2006, s. 84-91
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Tidskriftsartikel (refereegranskat)abstract
- Simulation models of urban rail operations are valuable tools for analysis of the operations of complex rail transit systems. A framework is presented for the application of rail simulation that includes calibration, validation, evaluation methodology, and interpretation of results. Methods that can be used at each step to facilitate the application are discussed. In particular, approaches are presented for calibration of model parameters and inputs, such as dynamic arrival and alighting rates at stations. Application of simulation tools can be greatly enhanced by the use of train circuit occupancy data collected by automated control systems. A new rail simulation model, SimMetro, specifically designed for service performance analysis taking into account the major sources of uncertainty in operations, is also presented. A case study is used to illustrate the applicability of the proposed framework in testing alternative real-time control strategies.
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| 28. |
- Koutsopoulos, Haris N., et al.
(författare)
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Simulation of urban rail operations : Models and calibration methodology
- 2019
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Ingår i: Transport Simulation: Beyond Traditional Approaches. - : Taylor & Francis Group. ; , s. 153-170
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- SimMETRO is a microscopic, dynamic, stochastic simulator of urban rail operations (METRO), specifically designed for service performance analysis, and the evaluation of operations and strategies for a real-time control of subway systems. SimMETRO employs a detailed representation of the network, rolling stock, signal control, demand, schedule and dispatching. In particular, the various sources of stochasticity in operations are explicitly captured. This chapter presents approaches for the calibration of model parameters and input (such as dynamic arrival and alighting rates), and a case study illustrates the applicability of the model and the proposed calibration methodology. After calibration, the RMSE of block run times (relative to actual times as reported by the train detection system) was reduced by 60% as compared to the default values. The calibrated demand was in good agreement with recent counts of arrival rates at the stations.
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| 29. |
- Kusuma, Andyka, et al.
(författare)
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Critical Gap Analysis of Dual Lane Roundabouts
- 2011
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Ingår i: 6th international symposium on highway capacity and quality of service. - : Elsevier BV. ; , s. 709-717
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Konferensbidrag (refereegranskat)abstract
- Roundabouts are increasingly popular because of their performance in terms of safety, capacity, and cost. Roundabouts have the potential to reduce accident risk since the traffic flows merge and diverge at small angles, and low speeds. Under certain conditions, roundabouts also improve the flow of traffic at the intersection, compared to other choices. In this paper we present a methodology for estimating an important input in the calculation of the capacity of roundabouts: the critical gap. The critical gap is the smallest gap that a driver is willing to accept to merge with the circulating traffic and mainly determines the gap acceptance behavior of the driver. The critical gap is not directly observable. Only gaps that drivers have accepted or rejected are observed. These gaps define upper and lower values for the underlying critical gap but not its exact value. The paper builds on previous literature proposing a rigorous statistical methodology for the estimation of the critical gap, and demonstrates its application through field measurements. It is assumed that the critical gap has a lognormal distribution among the driver population with a mean value that is a function of a number of explanatory variables. Based on these assumptions the critical gap and its distribution can then be estimated using maximum likelihood. A case study in a dual lane roundabout in Stockholm is used to illustrate the proposed methodology using video and other data. The results show that the critical gap depends, among other factors, on the target lane (near or far), the type of the vehicle. The results are aslo compared to values recommended by other studies.
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| 30. |
- Liu, Tianyou, et al.
(författare)
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Modeling the Duration of the Impact of Unplanned Disruptions on Passenger Trips Using Smartcard Data in Urban Rail Systems
- 2023
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Ingår i: URBAN RAIL TRANSIT. - : Springer Nature. - 2199-6687. ; 9:3, s. 266-279
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Tidskriftsartikel (refereegranskat)abstract
- Many urban rail systems operate near capacity given the rapid increase in passenger demand, and unplanned disruptions are unavoidable. From a passenger perspective, the duration of trip delays is a major concern, and passenger trip delays may be longer than the train delays. Several studies have focused on predicting train delays, but the research on the duration of the disruption impacts on passenger trips is limited given that the duration is not observed directly. This paper proposes a probabilistic method to estimate the disruption impact duration using smartcard data, explores statistical and machine learning models to predict the duration of impacts on passengers, and identifies influencing factors including incident characteristics, operating conditions, infrastructure, external factors, and demand. The results highlight that prediction accuracies are acceptable for multiple linear regression, accelerated failure time, and random forest models. Disruptions caused by power failures have longer impact durations than other causes, followed by platform screen doors. The fixed block signaling system leads to a larger disruption duration than the moving block system. The study provides, for the first time, a data-driven approach to understanding the duration of the impact of disruptions on passenger trips using smartcard data which can facilitate timely and informed decision-making under unplanned disruptions.
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| 31. |
- Ma, Xiaoliang, et al.
(författare)
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Evaluation of Real-Time Travel Time Estimation Methods and Disruption Warning Using Noisy Automatic Vehicle Identification Measurements
- 2009
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Ingår i: Transportation Research Board Annual Meeting 2009 Paper.
-
Konferensbidrag (refereegranskat)abstract
- To support the implementation of a real-time traffic information system in Stockholm using automatic vehicle identification (AVI) data, a travel time analysis platform has been developed. The platform is composed of a client-side travel time data analysis program and a database server where historical travel time data are stored. In the study, several existing freeway travel time estimation algorithms and their modifications were implemented in the travel time analysis program, and evaluated using four months data collected on urban streets and arterials in and near the city of Stockholm. The advantages and disadvantages of those algorithms are analyzed using the highly noisy travel time measurements. The results show that with modifications in the parameter settings and the algorithms themselves, the methods are capable of estimating the travel times from the noise-corrupted urban data. In addition to the travel time estimation, the paper presents a simple data disruption recognition approach on the way toward a more comprehensive disruption and incident warning system.
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| 32. |
- Ma, Xiaoliang, et al.
(författare)
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EVALUATION OF SIGNAL PLANS FOR SUSTAINABLITY USING MICROSCOPIC TRAFFIC IMPACT MODELS
- 2011
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Ingår i: TRANSPORT DYNAMICS. - : HONG KONG SOC TRANSPORTATION STUDIES LTD. - 9789889884796 ; , s. 515-522
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Konferensbidrag (refereegranskat)abstract
- The continuous increases of motor vehicles and travel demand in metropolitan areas have brought many challenges to sustainable transport development because of the impacts on energy and environment. This paper presents a simulation-based approach to model and analyze traffic impacts by combining microscopic traffic and instantaneous emissions models. The method is applied for improvement of traffic management measures, concerning not only mobility but also environmental consequences. The study illustrates the essential model calibration procedures that finely tune the CMEM emission model and VISSIM microscopic traffic simulation model using corresponding emission and traffic flow data. The calibrated models have been applied collaboratively in a detailed study on evaluating environmental impacts of two optimal signal control strategies at an isolated intersection in Wuhan.
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| 33. |
- Ma, Zhenliang, et al.
(författare)
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Near-on-demand mobility. The benefits of user flexibility for ride-pooling services
- 2022
-
Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 135
-
Tidskriftsartikel (refereegranskat)abstract
- Mobility-On-Demand (MoD) services have been transforming the urban mobility ecosystem. However, they raise a lot of concerns for their impact on congestion, Vehicle Miles Traveled (VMT), and competition with transit. There are also questions about their long-term survival because of inherent inefficiencies in their operations. Considering the popularity of the MoD services, increasing ride-pooling is an important means to address these concerns. Shareability depends not only on riders' attitudes and preferences but also on operating models deployed by providers. The paper introduces an advance requests operating model for ride pooling, users may request rides in advance of their desired departure times. A platform with efficient algorithms for request matching, vehicle routing, rebalancing, and flexible user preferences is developed. Data from Chengdu, China, and New York, United States are used to evaluate the performance of the advance requests system. The impact of various design aspects of the system (e.g. advance requests horizon, vehicle capacity) on its performance is investigated. The sensitivity of the results to user preferences in terms of the level of service (time to be served and excess trip time), willingness to share and place requests in advance, and traffic conditions are explored. The results suggest that significant benefits in terms of sustainability, level of service, and fleet utilization can be realized when advance requests are along with an increased willingness to share. Furthermore, even "near-on-demand " (relative short planning horizons) operations can offer benefits for all stakeholders (users, operators, cities).
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| 34. |
- Mo, Baichuan, et al.
(författare)
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Ex Post Path Choice Estimation for Urban Rail Systems Using Smart Card Data : An Aggregated Time-Space Hypernetwork Approach
- 2023
-
Ingår i: Transportation Science. - : Institute for Operations Research and the Management Sciences (INFORMS). - 0041-1655 .- 1526-5447. ; 57:2, s. 313-335
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes an ex post path choice estimation framework for urban rail systems using an aggregated time-space hypernetwork approach. We aim to infer the actual passenger flow distribution in an urban rail system for any historical day using the observed automated fare collection (AFC) data. By incorporating a schedule-based dynamic transit network loading (SDTNL) model, the framework captures the crowding correlation among stations and the interaction between the path choice and passenger left behind, which is important for the path choice estimation in a “near-capacity” operated urban rail system. The path choice estimation is formulated as an optimization problem, which aims to minimize the difference between the model-derived and observed information with path choice parameters as decision variables. The original problem is intractable because of nonlinear (logit model) and nonanalytical (SDTNL) constraints. A solution procedure is proposed to decompose the original problem into three tractable subproblems, which can be solved efficiently. Solving the decomposed problem is equivalent to finding a fixed point. We prove that the solution to the original problem is the same as the decomposed problem (i.e., the fixed point) when passenger path choices follow the predefined behavior model. If this condition does not hold, the solution of the original problem is proved to be an “almost fixed point” for the decomposed problem. The model is validated using both synthetic and real-world AFC data from a major urban railway system. The analysis with synthetic data validates the model’s effectiveness in estimating path choice parameters and left behind probabilities, which outperforms state-of-art simulation-based optimization methods and probabilistic models in both accuracy and efficiency. The analysis using actual data shows that the estimated path shares are more reasonable than the baseline uniform path shares and survey-derived path shares. The model estimation is robust to different initial parameter values and AFC data from various dates.
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| 35. |
- Mwesige, Godfrey, et al.
(författare)
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A Model and Its Applications for Predicting Passing Rate at Passing Zones on Two-Lane Rural Highways
- 2016
-
Ingår i: Journal of transportation engineering. - : American Society of Civil Engineers (ASCE). - 0733-947X .- 1943-5436. ; 142:3
-
Tidskriftsartikel (refereegranskat)abstract
- Passing zones are designed to provide sufficient sight distance for fast vehicles to pass safely slow vehicles and contribute to operational efficiency of two-lane highways. However, lack of suitable models to predict passing rate and capacity has made it difficult to quantify operational benefits of passing zones. In this paper, a model is proposed to predict passing rate in the subject direction at passing zones using traffic and geometric factors. The model is developed based on speed and passing data collected at 19 passing zones in Uganda using pneumatic tube classifiers and video recordings. Findings show that passing rates depend on the length of the passing zone, absolute vertical grade, traffic volume in two travel directions, directional split, 85th percentile speed of free-flow vehicles and percent heavy vehicles in the subject direction. The peak passing rate also referred to as the passing capacity occurs at 200, 220, and 240 vehicles/h in the subject direction for 50/50, 55/45, and 60/40 directional splits, respectively. The model could potentially be applicable in planning, design, and safety evaluation of two-lane rural highways.
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| 36. |
- Mwesige, Godfrey, et al.
(författare)
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Risk appraisal of passing zones on two-lane rural highways and policy applications
- 2016
-
Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 90, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- Passing on two-lane rural highways is associated with risks of head-on collision resulting from unsafe completion of passing maneuvers in the opposite traffic lane. In this paper, we explore the use of time to-collision (ITC) as a surrogate safety measure of the risk associated with passing maneuvers. Logistic regression models to predict the probability to end the passing maneuver with TTC less than 2 or 3 s-threshold were developed with the time-gap from initiation of the maneuver to arrival of the opposite vehicle (effective accepted gap), and the passing duration as explanatory variables. The data used for model estimation was collected using stationary tripod-mounted camcorders at 19 passing zones in Uganda. Results showed that passing maneuvers completed with TTC less than 3 s are unsafe and often involved sudden speed reduction, flashing headlights, and lateral shift to shoulders. Model sensitivity analysis was conducted for observed passing durations involving passenger cars or short trucks (2-3 axles), and long trucks (4-7 axles) as the passed vehicles for 3 s TTC-threshold. Three risk levels were proposed based on the probability to complete passing maneuvers with TTC less than 3 s for a range of opposite direction traffic volumes. Applications of the results for safety improvements of two-lane rural highways are also discussed. (C) 2016 Elsevier Ltd. All rights reserved.
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| 37. |
- Nissan, Albania, 1957-
(författare)
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Evaluation of Variable Speed Limits : Empirical Evidence and Simulation Analysis of Stockholm’s Motorway Control System
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Variable Speed Limits (VSL) are often used to improve traffic conditions on congested motorways. VSL can be implemented as mandatory or advisory. The objective of the thesis isto study in detail the effectiveness of VSL. The focus is on both, design parameters and conditions under which VSL are most effective. The MCS system on the E4 motorway inStockholm is used as a case study. The evaluation was conducted using empirical methods (including aggregate data from microwave sensors and other sources, and disaggregate data from a mobile study), and microscopic traffic simulation. The empirical analysis is based on before and after VSL data, including evaluation of individual measures of performance, and multivariate analysis in the form of the fundamental diagram, and speed-density relationships. The results from the empirical study are mixed with an indication that driver behavior has a strong impact on the effectiveness of the system. The microscopic traffic simulation analysis included the development of a platform for testing VSL and more generally motorway control strategies. The simulation platform was calibrated and validated with the empirical data and includes in addition to VSL, and Automatic Incident Detection (AID) system, the ALINEA ramp metering algorithm. The test-platform allows the testing of different control strategies and various combinations of control strategies, under different scenarios and in a controlled environment. The results from the simulation study indicate that driver compliance is an important factor and VSL performance quickly deteriorates as compliance rate drops. Hence, VSL should be implemented as mandatory instead of advisory. In addition, mandatory VSL can be effective both, under incident and moderately congested conditions. A combined VSL and ramp metering strategy can be most effective in reducing travel time, improving traffic conditions on the motorway. Furthermore, the results indicate that such a strategy also has the least impact on the flows entering the motorway from the ramps.
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| 38. |
- Rahmani, Mahmood, 1977-, et al.
(författare)
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Floating car and camera data fusion for non-parametric route travel time estimation
- 2014
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Ingår i: Procedia Computer Science. - : Elsevier B.V.. - 1877-0509. ; , s. 390-395
-
Konferensbidrag (refereegranskat)abstract
- Traffic management centers take advantage of various data collection systems ranging from stationary sensors e.g. automated vehicle identification systems to mobile sensors e.g. fleet management systems. Each type of data collection system has its own advantages and disadvantages. Stationary sensors has less measurement noise than mobile sensors but their network coverage is limited. On the other hand, mobile sensors cover expand areas of road networks but they have less penetration rate and frequency of reports. Traffic state estimation can benefit from fusion of data from various sources as they complement each other. This paper introduces a route travel time estimation method that aggregates data from two traffic data sources, automated number plate recognition system and floating car data.
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| 39. |
- Rahmani, Mahmood, 1977-, et al.
(författare)
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Travel time estimation from sparse floating car data with consistent path inference : A fixed point approach
- 2017
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Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 85, s. 628-643
-
Tidskriftsartikel (refereegranskat)abstract
- Estimation of urban network link travel times from sparse floating car data (FCD) usually needs pre-processing, mainly map-matching and path inference for finding the most likely vehicle paths that are consistent with reported locations. Path inference requires a priori assumptions about link travel times; using unrealistic initial link travel times can bias the travel time estimation and subsequent identification of shortest paths. Thus, the combination of path inference and travel time estimation is a joint problem. This paper investigates the sensitivity of estimated travel times, and proposes a fixed point formulation of the simultaneous path inference and travel time estimation problem. The methodology is applied in a case study to estimate travel times from taxi FCD in Stockholm, Sweden. The results show that standard fixed point iterations converge quickly to a solution where input and output travel times are consistent. The solution is robust under different initial travel times assumptions and data sizes. Validation against actual path travel time measurements from the Google API and an instrumented vehicle deployed for this purpose shows that the fixed point algorithm improves shortest path finding. The results highlight the importance of the joint solution of the path inference and travel time estimation problem, in particular for accurate path finding and route optimization.
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| 40. |
- Silvano, Ary P., 1975-, et al.
(författare)
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Free flow speed estimation : A probabilistic, latent approach. Impact of speed limit changes and road characteristics
- 2020
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Ingår i: Transportation Research Part A. - : Elsevier Ltd. - 0965-8564 .- 1879-2375. ; 138, s. 283-298
-
Tidskriftsartikel (refereegranskat)abstract
- The estimation of the free flow speed (FFS) distribution is important for capacity analysis, determination of the level-of-service, and setting speed limits. Subjective time headway thresholds have been commonly used to identify vehicles travelling under free flow speed conditions i.e., vehicles whose speeds are not influenced by the vehicle in front. Since, the headway a driver operates under the free flow state is subjective and varies from driver to driver, such approaches can introduce biases in the FFS estimation. Therefore, in this paper a parametric probabilistic latent approach is proposed based on discrete choice utility theory to estimate the FFS distribution on urban roads and simultaneously the probability that drivers perceive their state as constrained by the vehicle in front. This methodology is used to estimate the impacts of road characteristics and Posted Speed Limit (PSL) changes on the FFS distribution using an extensive dataset of speed observations from urban roads with varying characteristics. The results show that the simultaneous estimation of the free flow speed distribution and the state the driver is in (e.g., free or constrained) is feasible. The analysis indicates that the FFS is influenced by several road characteristics such as land use, on-street parking and the presence of sidewalks. The PSL change impacts not only the distribution of the free flow vehicles but also the speed distribution of the constrained vehicles. The constrained probabilities vary depending on the PSL change with higher probabilities for lower speed limits.
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| 41. |
- Silvano, Ary P., 1975-
(författare)
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Impacts of Speed Limits and Information Systems on Speed Choice from a Safety Perspective.
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Driving a vehicle is considered a demanding task in a complex dynamic environment. For instance, driving a vehicle on urban roads, where motorized vehicles meet vulnerable road users (VRUs) creates a multifaceted environment with difficult trade-offs and interactions. Additionally, in-vehicle technology developments are being introduced to ease drivers with the driving task. However, these developments are changing “traditional” driving increasing drivers’ response in terms of information processing, thus making the driving task more demanding in some respects. Therefore, the aim of the present research is to further investigate drivers’ speed choice under varying traffic management regulations and in-vehicle warning systems.
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| 42. |
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| 43. |
- Silvano, Ary P., 1975-, et al.
(författare)
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When do drivers yield to cyclists at unsignalized roundabouts? : Empirical evidence and behavioral analysis
- 2015
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2520, s. 25-31
-
Tidskriftsartikel (refereegranskat)abstract
- Cycling popularity has shown an increasing trend during the last decades in many cities of Europe and USA because of its environmental and health benefits. However, cyclists are frequently involved in traffic accidents, especially, when they interact with vehicles at unsignalized intersections. There is still lack of evidence and analysis on how such interaction is performed. This paper explores empirical evidence of the vehicle-bicycle interaction on a typical Swedish roundabout, and provides insights into factors influencing car drivers’ yielding decisions when they interact with cyclists. The vehicle-bicycle interaction was divided into category groups (Non-Conflict, Conflict, Yield, and Non-Yield) and their speed differences were analyzed by group. Furthermore, a discrete choice model was developed to estimate behavioral aspects of such interactions. The observed data showed a higher and significant speed variation among vehicles, whereas bicycles exhibited lower variation across the groups. The modelling results revealed that the yielding probability decreased when the speed of the vehicle was higher. On the other hand, the bicycle speed had little impact on drivers’ decision to yield. More importantly, the yielding probability increased significantly by the proximity of the cyclist to the conflicting zone. The yielding rate of drivers can be improved by keeping vehicles’ speed under 20 km/h, as drivers have the capacity to detect and yield to cyclists.
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| 44. |
- Stojanovski, Todor
(författare)
-
Urban Form and Mobility - Analysis and Information to Catalyse Sustainable Development
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Urban transportation today consumes scarce resources of fossil fuels and it is a major cause for environmental damage and accelerating climate change. To achieve sustainable mobility in the cities, it is necessary to improve energy efficiency and lower carbon emissions through the promotion of walking, cycling and especially public transportation.The urban form and the embeddedness of automobility is a challenging obstacle on the way towards sustainable mobility and cities. Many neighbourhoods and cities, particularly in developed countries like Sweden, were specifically designed and developed to accommodate the private car, individual mobility and freedom of movement. It is impossible to walk or cycle and the public transportation is not competitive. The lack of mobility choices in these neighbourhoods and cities hinders the possibilities to shift towards more sustainable travel alternatives. Urban designers and planners can help with redesigning these neighbourhoods and creating urban forms that encourage walking, cycling and increased use of public transportation if they are aware about the possible modal shares, energy efficiency, environmental performance and carbon implications of transportation in existing and newly planned neighbourhoods.This Doctoral Thesis examines Swedish urbanisation and the historical integration of public transportation in competition with other transportation modes. It analyses emergence of typical neighbourhoods that oriented towards walking (the pre-industrial city), to public transportation (the industrializing city), to the private automobile (the modern/industrial city) and ultimately to a wide range of mobility choices (the postmodern/post-industrial city with sustainable city neighbourhoods). It investigates furthermore the effect of urban form variables (including neighbourhood type) on travel (modal shares of public transportation). Based upon this empirical knowledge, the Doctoral Thesis proposes a mobility choices model based on urban form and accessibility factors commonly used in urban planning, design and development practices. The mobility choices model produces heat maps and visually informs about the integration with walking, cycling, public transportation and private car, modal shares, carbon emissions and transportation energy use. This information can (potentially) trigger urban transformation or redesign car-oriented neighbourhoods to better integrate energy efficient and environmentally friendly mobility alternatives and catalyse the development of more sustainable cities.
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| 45. |
- Tapani, Andreas, 1978-
(författare)
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Traffic Simulation Modelling of Rural Roads and Driver Assistance Systems
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microscopic traffic simulation has proven to be a useful tool for analysis of varioustraffic systems. This thesis consider microscopic traffic simulation of rural roads andthe use of traffic simulation for evaluation of driver assistance systems.A traffic simulation modelling framework for rural roads, the Rural Traffic Simulator(RuTSim), is developed. RuTSim is designed for simulation of traffic on singlecarriageway two-lane rural roads and on rural roads with separated oncoming trafficlanes. The simulated traffic may be interrupted by vehicles entering and leaving themodelled road at intersections or roundabouts.The RuTSim model is applied for analysis of rural road design alternatives.Quality-of-service effects of three alternatives for oncoming lane separation of anexisting Swedish two-lane road are analysed. In another model application, RuTSimis used to simulate traffic on a Dutch two-lane rural road. This application illustratesthat the high level of model detail of traffic micro-simulation may call for use of differentmodelling assumptions regarding driver behaviour for different applications,e. g. for simulation of traffic in different cultural regions.The use of traffic simulation for studies of driver assistance systems facilitateimpact analyses already at early stages of the system development. New and additionalrequirements are however then placed on the traffic simulation model. It isnecessary to model both the system functionality of the considered driver assistancesystem and the driver behaviour in system equipped vehicles. Such requirements canbe analysed using RuTSim.In this thesis, requirements on a traffic simulation model to be used for analysisof road safety effects of driver assistance systems are formulated and investigatedusing RuTSim. RuTSim is also applied for analyses of centre line rumble stripson two-lane roads, of an overtaking assistant and of adaptive cruise control. Thesestudies establish that the assumptions made regarding driver behaviour are crucialfor traffic simulation based analyses of driver assistance systems.
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| 46. |
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| 47. |
- Toledo, Tomer, et al.
(författare)
-
Estimation of an integrated driving behavior model
- 2009
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Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 17:4, s. 365-380
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the methodology and results of estimation of an integrated driving behavior model that attempts to integrate various driving decisions. The model explains lane changing and acceleration decisions jointly and so, captures inter-dependencies between these behaviors and represents drivers' planning capabilities. It introduces new models that capture drivers' choice of a target gap that they intend to use in order to change lanes, and acceleration models that capture drivers' behavior to facilitate the completion of a desired lane change using the target gap. The parameters of all components of the model are estimated simultaneously with the maximum likelihood method and using detailed vehicle trajectory data collected in a freeway section in Arlington, Virginia. The estimation results are presented and discussed in detail.
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| 48. |
- Toledo, Tomer, et al.
(författare)
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Estimation of Vehicle Trajectories with Locally Weighted Regression
- 2007
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Ingår i: Transportation Research Record. - : Transportation Research Board. - 0361-1981 .- 2169-4052. ; :1999, s. 161-169
-
Tidskriftsartikel (refereegranskat)abstract
- Vehicle trajectory data are important for calibrating driver behavior models (e.g., car following, acceleration, lane changing, and gap acceptance). The data are usually collected through imaging technologies, such as video. Processing these data may require substantial effort, and the resulting trajectories usually contain measurement and processing errors while also missing data points. An approach is presented to the processing of position data to develop vehicle trajectories and consequently speed and acceleration profiles. The approach uses local regression, a method well suited for mapping highly nonlinear functions. The proposed methodology is applied to a set of position data. The results demonstrate the value of the method to development of vehicle trajectories and speed and acceleration profiles. The conducted sensitivity analysis also shows that the method is rather robust regarding measurement errors and missing values.
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| 49. |
- Toledo, Tomer, et al.
(författare)
-
Integrated driving behavior modeling
- 2007
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Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 15:2, s. 96-112
-
Tidskriftsartikel (refereegranskat)abstract
- This paper develops, implements and tests a framework for driving behavior modeling that integrates the various decisions, such as acceleration, lane changing and gap acceptance. Furthermore, the proposed framework is based on the concepts of short-term goal and short-term plan. Drivers are assumed to conceive and perform short-term plans in order to accomplish short-term goals. This behavioral framework supports a more realistic representation of the driving task, since it captures drivers’ planning capabilities and allows decisions to be based on anticipated future conditions. An integrated driving behavior model, which utilizes these concepts, is developed. The model captures both lane changing and acceleration behaviors. The driver’s short-term goal is defined by the target lane. Drivers who wish to change lanes but cannot change lanes immediately, select a short-term plan to perform the desired lane change. Short-term plans are defined by the various gaps in traffic in the target lane. Drivers adapt their acceleration behavior to facilitate the lane change using the target gap. Hence, inter-dependencies between lane changing and acceleration behaviors are captured.
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| 50. |
- Tuncel, Kerem, et al.
(författare)
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An integrated ride-matching and vehicle-rebalancing model for shared mobility on-demand services
- 2023
-
Ingår i: Computers & Operations Research. - : Elsevier BV. - 0305-0548 .- 1873-765X. ; 159
-
Tidskriftsartikel (refereegranskat)abstract
- Shared mobility on demand (MoD) services are receiving increased attention as many high-volume ride-hailing companies are offering shared services (e.g. UberPool, LyftLine) at an increasing rate. Also, the advent of autonomous vehicles (AVs) promises further operational opportunities to benefit from these developments as AVs enable a centrally operated and fully connected fleet. There are two fundamental tasks for a shared MoD service: ride-matching and vehicle-rebalancing. Traditionally, these two tasks are optimized sequentially and independently. The paper formulates an integrated ride-matching and vehicle-rebalancing problem for shared MoD services which simultaneously optimizes these two tasks. We propose a graph-based methodology to solve the integrated ride-matching and vehicle-rebalancing problem with a novel rebalancing cost term quantifying supply contributions of vehicle scheduling to zonal supply deficit balances (deviations from the desired supply level) in the network. The integrated model performance is validated using a large-scale empirical shared MoD dataset by comparing with state-of-the-art sequential models. Generally, the integrated model improves the level of service and sustainability performance compared to the sequential model. The detailed analysis shows that the vehicle rebalancing in the integrated model is replaced by a more effective ride-matching and penalizing singly served trips in the integrated model can further improve its sustainability performance.
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