| 1. |
- Ben-Akiva, Moshe, et al.
(författare)
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Traffic Simulation with MITSIMLab
- 2010
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Ingår i: Fundamentals of Traffic Simulation. - New York, NY : Springer. - 1441961429 ; , s. 233-268
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Bokkapitel (refereegranskat)abstract
- MITSIMLab (MIcroscopic Traffic SIMulation Laboratory) is a microscopic traffic simulation model that evaluates the impacts of alternative traffic management system designs at the operational level and assists in their subsequent refinement. MITSIMLab models the travel and driving behavior of individual vehicles, the detailed movement of transit vehicles, and the various control and information provision strategies through a generic controller. A calibration methodology for important parameters and inputs was also developed. The model has been extended to address the special driving behavior evidenced in urban networks and has been used as a test bed for the evaluation of advanced traveler information systems (ATIS). Calibration and validation results from networks in the United States and Europe are discussed.
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| 2. |
- Burghout, Wilco, et al.
(författare)
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DYMOBUS: dynamic mesoscopic modelling of bus public transport
- 2009
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Ingår i: Conference proceedings to ITS 2009 conference.
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Konferensbidrag (refereegranskat)abstract
- In today’s public bus transport punctuality is one of the main problems to deal with for traffic planners and operators, especially in large cities such as Stockholm. The current static models do not handle congestion delays and the interaction between bus and car traffic, leading to overly optimistic timetables and hard to manage delays. In the DYMOBUS project (Funded by VINNOVA and City of Stockholm) a dynamic modelling tool was developed in order to study these interactions. This paper discusses a mesoscopic, mixed-traffic, a transit simulation model designed to support evaluation of operations planning and control, especially in the context of Advanced Public Transportation Systems (APTS). Examples of applications include frequency determination, evaluation of real time control strategies for schedule maintenance and restoration from major disruptions. The transit simulation component is designed to represent realistically the uncertainty in operations, in order to assess service reliability. The simulation models all sources of uncertainty: chaining of trips, travel time variability, behavior at stops and a detailed representation of passenger demand at the various stops. Unlike most previous efforts in this area, the simulation model is built on the platform of a mesoscopic traffic simulation model, which allows modeling of the operations of large-scale transit systems. A Tel-Aviv case study demonstrates the transit simulation capabilities of the model.
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| 3. |
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| 4. |
- Cats, Oded, 1983-
(författare)
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Dynamic Modelling of Transit Operations and Passenger Decisions
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Efficient and reliable public transport systems are fundamental in promoting green growth developments in metropolitan areas. A large range of Advanced Public Transport Systems (APTS) facilitates the design of real-time operations and demand management. The analysis of transit performance requires a dynamic tool that will enable to emulate the dynamic loading of travelers and their interaction with the transit system. BusMezzo, a dynamic transit operations and assignment model was developed to enable the analysis and evaluation of transit performance and level of service under various system conditions and APTS. The model represents the interactions between traffic dynamics, transit operations and traveler decisions. The model was implemented within a mesoscopic traffic simulation model. The different sources of transit operations uncertainty including traffic conditions, vehicle capacities, dwell times, vehicle schedules and service disruptions are modeled explicitly. The dynamic path choice model in BusMezzo considers each traveler as an adaptive decision maker. Travelers’ progress in the transit system consists of successive decisions that are defined by the need to choose the next path element. The evaluations are based on the respective path alternatives and their anticipated downstream attributes. Travel decisions are modeled within the framework of discrete random utility models. A non-compensatory choice-set generation model and the path utility function were estimated based on a web-based survey. BusMezzo enables the analysis and evaluation of proactive control strategies and the impacts of real-time information provision. Several experiments were conducted to analyze transit performance from travelers, operator and drivers perspectives under various holding strategies. This analysis has facilitated the design of a field trial of the most promising strategy. Furthermore, a case study on real-time traveler information systems regarding the next vehicle arrival time investigated the impacts of various levels of coverage and comprehensiveness. As passengers are more informed, passenger loads are subject to more fluctuation due to the traveler adaptations.
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| 5. |
- Cats, Oded, et al.
(författare)
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Effect of real-time transit information on dynamic passenger path choice.
- 2011
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981. ; 2217, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Real-time information is increasingly being implemented in transit networks worldwide. The evaluation of the effect of real-time information requires dynamic modeling of transit operations and of passenger path choices. This paper presents a dynamic transit analysis and evaluation tool that represents time-tables, operation strategies, real-time information, adaptive passenger choices, and traffic dynamics at the network level. Transit path choices are modeled as a sequence of boarding, walking and alighting decisions that passengers undertake when carrying out their journey. The model is applied to the Metro network of Stockholm, Sweden area under various operating conditions and information provision scenarios, as a proof of concept. An analysis of the results indicates substantial path choice shifts and potential time savings associated with more comprehensive real-time information provision and transfer coordination improvements.
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| 6. |
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| 7. |
- Cats, Oded, et al.
(författare)
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Evaluation of real-time holding strategies for improved bus service reliability
- 2010
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Ingår i: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC. - Madeira, Portugal. - 9781424476572 ; , s. 718-723
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Konferensbidrag (refereegranskat)abstract
- Service reliability is one of the main measures of performance determining transit system level of service. Holding control strategies are a common transit operations practice aimed to reduce transit service unreliability by setting criteria for departure fromtime point stops. In order to adequately analyze the sources of uncertainty involved with transit performance, it is essential to model dynamically the interactions between traffic conditions, passenger demand and transit operations. BusMezzo, a transit simulation model has been developed on a platform of a mesoscopic traffic simulation model, which enables the representation of large-scale transit systems. The model implements severalreal-time holding strategies. It is used to evaluate the application of these strategies in areal-world high-demand bus line in the Tel Aviv metropolitan area, under various scenarios. An analysis of the results suggests that a holding strategy based on the mean headway from the preceding bus and the next bus, restricted by a maximum allowableholding time, is especially efficient.
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| 8. |
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| 9. |
- Cats, Oded, et al.
(författare)
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Mesoscopic Modeling of Bus Public Transportation
- 2010
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2188, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of public transport system performance and level of service in urban areas is essential. Dynamic modeling of traffic conditions, passenger demand, and transit operations is important to represent adequately the complexity of and the interactions between these components in modern public transportation systems. This paper presents a transit simulation model designed to support evaluation of operations planning and control, especially in the context of advanced public transportation systems. Unlike most previous efforts in this area, the simulation model is built on a platform of a mesoscopic traffic simulation model, which allows modeling or the operation dynamics of large-scale transit systems, taking into account the main sources of service uncertainty and stochasticity. The capabilities of Mezzo as an evaluation tool of transit operations are demonstrated with an application to a real-world, high-demand bus line in metropolitan Tel Aviv, Israel, under various scenarios. The application shows that important phenomena such as bus bunching are reproduced realistically. A comparison of simulated running times and headway distributions with field data shows the model is capable of replicating observed data.
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| 10. |
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| 11. |
- Farah, Haneen, et al.
(författare)
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Passing behavior on two-lane highways
- 2010
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Ingår i: Transportation Research Part F. - : Elsevier BV. - 1369-8478 .- 1873-5517. ; 13:6, s. 355-364
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Tidskriftsartikel (refereegranskat)abstract
- Two-lane highways make up a substantial proportion of the road network in most of the world. Passing is among the most significant driving behaviors on two-lane highways. It substantially impacts the highway performance. Despite the importance of the problem, few studies attempted to model passing behavior. In this research, a model that attempts to capture both drivers' desire to pass and their gap acceptance decisions to complete a desired passing maneuver is developed and estimated using data on passing maneuvers collected with a driving simulator. Sixteen different scenarios were used in the experiment in order to capture the impact of factors related to the various vehicles involved, the road geometry and the driver characteristics in the model. A passing behavior model is developed that includes choices in two levels: the desire to pass and the decision whether or not to accept an available passing gap. The probability to complete a passing maneuver is modeled as the product of the probabilities of a positive decision on both these choices. The estimation results show that modeling the drivers' desire to pass the vehicle in front has a statistically significant contribution in explaining their passing behavior. The two sub-models incorporate variables that capture the impact of the attributes of the specific passing gap that the driver evaluates and the relevant vehicles, the geometric characteristics of the road section and the driver characteristics and account for unobserved heterogeneity in the driver population.
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| 12. |
- 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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| 13. |
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| 14. |
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| 15. |
- Toledo, Tomer, et al.
(författare)
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Alternative Definitions of Passing Critical Gaps
- 2011
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Ingår i: Transportation Research Record. - : SAGE Publications. - 0361-1981 .- 2169-4052. ; :2260, s. 76-82
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Tidskriftsartikel (refereegranskat)abstract
- A substantial proportion of the road network in most countries consists of two-lane highways. Available gaps for passing are a fundamental element in the operation of such highways. Providing passing opportunities is important for reducing the formation of vehicle platoons in the traffic flow, increasing the level of service, and improving safety. Passing opportunities also affect fuel consumption and emissions. Despite the importance of passing on two-lane highways, few studies have focused on exploring passing gap definitions when modeling passing behavior. Research was done to investigate various definitions of passing gaps, and these definitions were used to develop passing gap acceptance models. Data on passing maneuvers collected with a driving simulator were used to develop and calibrate three models. The generic structure of these models was composed of the drivers' desire to pass and their gap acceptance decisions. The impact of traffic characteristics, road geometry, and driver characteristics was included in these models. The results show that the passing gap definition has a significant impact on the models' ability to explain passing behavior. Moreover, the estimation results show that modeling a driver's desire to pass the vehicle ahead has a statistically significant contribution in explaining passing behavior. Variables that capture the impact of the traffic conditions, geometric characteristics of the road section, driver characteristics, and the unobserved heterogeneity in the driver population were found to have a significant impact on drivers' desire to pass and their gap acceptance decisions.
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| 16. |
- Toledo, Tomer, et al.
(författare)
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Calibration of Microscopic Traffic Simulation Models with Aggregate Data
- 2004
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Ingår i: CALIBRATION AND VALIDATION OF SIMULATION MODELS 2004. - : SAGE Publications. - 0309094704 ; , s. 10-19
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Konferensbidrag (refereegranskat)abstract
- A framework for the calibration of microscopic traffic simulation models using aggregate data is presented. The framework takes into account the interactions between the various inputs and parameters of the simulator by estimating origin-destination (O-D) flows jointly with the behavioral parameters. An optimization-based approach is used for the joint calibration. Since the calibration of the parameters depends on the estimated O-D flows and vice versa, the proposed framework is iterative. O-D estimation is based on the well-known generalized least squares estimator. A systematic search approach based on the complex algorithm is adopted for calibration of the behavioral parameters. This algorithm is particularly useful for the problem at hand since it does not require calculations of derivatives of the objective function. The applicability of the approach is demonstrated through its application to case studies using MITSIMLab, a microscopic traffic simulation model.
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| 17. |
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| 18. |
- Toledo, Tomer, et al.
(författare)
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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
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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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| 19. |
- 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
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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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| 20. |
- Toledo, Tomer, et al.
(författare)
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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
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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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| 21. |
- Toledo, Tomer, et al.
(författare)
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Mesoscopic simulation for transit operations
- 2010
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Ingår i: Transportation Research Part C. - : Elsevier BV. - 0968-090X .- 1879-2359. ; 18:6, s. 896-908
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a transit simulation model designed to support evaluation of operations, planning and control, especially in the context of Advanced Public Transportation Systems (APTS). Examples of potential applications include frequency determination, evaluation of real-time control strategies for schedule maintenance and assessing the effects of vehicle scheduling on the level of service. Unlike most previous efforts in this area, the simulation model is built on a platform of a mesoscopic traffic simulation model, which allows modeling of the operation dynamics of large-scale transit systems taking into account the stochasticity due to interactions with road traffic. The capabilities of Mezzo as an evaluation tool of transit operations are demonstrated with an application to a real-world high-demand bus line in the Tel-Aviv metropolitan area under various scenarios. The headway distributions at two stops are compared with field observations and show good consistency between simulated and observed data.
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| 22. |
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| 23. |
- Toledo, Tomer, et al.
(författare)
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Statistical Validation of Traffic Simulation Models
- 2004
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Ingår i: CALIBRATION AND VALIDATION OF SIMULATION MODELS 2004. - : SAGE Publications. - 0309094704 ; , s. 142-150
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Konferensbidrag (refereegranskat)abstract
- Traffic simulation models support detailed analysis of the dynamics of traffic phenomena and are important tools for analysis of transportation systems. In order to evaluate correctly the impact of different traffic management schemes, simulation models must be able to replicate reality adequately. Model validation (i.e., the process of checking to what extent the model replicates reality) is discussed. The role of validation is defined within the scope of model development and calibration, and the framework for performing the validation is discussed. A hierarchy of statistical methods to validate different types of simulation outputs against observed data is examined. Also, a validation method is proposed on the basis of statistical tests on metamodels fitted to the observed and simulated data. A case study illustrates the applicability of the various methods.
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