302 research outputs found
Measuring Winners and Losers from the new I-35W Mississippi River Bridge
The opening of the replacement for the I-35W Mississippi River Bridge bridge on September 18th, 2008 provides a unique opportunity to evaluate the impacts generated by this additional link on network performance, and thus empirically test whether a Braess Paradox occurred. Using detailed GPS data to estimate travel times on links and for origin-destination pairs, this research Þnds that while on average travel time improved with the reopening of the bridge, the subsequent restoration of parts of the rest of the network to their pre-collapse conÞguration worsened travel times signiÞcantly on average. In all cases, the distribution of winners and losers indicates clear spatial patterns associated with these network changes. While no Braess paradox was found in this case, the research provides a method for measuring such phenomena.Network structure, travel behavior, transport geography, commuting, network disruption, Braess paradox
Intelligent Destination Recommender and Community Builder
Recommendation engines make use of machine learning techniques and generally deal with ranking and rating of products/users. With the help of this system we aim to suggest different destinations to users based on their interest and previous visits. Along with recommendations we also aspire to enable users to build travel communities for people sharing similar interests .This shall help travelers with planning ,meeting like-minded people,safety and enthralling experience.
As per the analysis done on pre-existing systems we discerned that enabling users to build a community of travelers visiting the same destination is an eccentric attribute proposed.
This distinctive attribute of building communities shall be implemented using the basics of clustering algorithms in Machine learning
Cost/benefit trade-offs for reducing the energy consumption of commercial air transportation (RECAT)
A study has been performed to evaluate the opportunities for reducing the energy requirements of the U.S. domestic air passenger transport system through improved operational techniques, modified in-service aircraft, derivatives of current production models, or new aircraft using either current or advanced technology. Each of the fuel-conserving alternatives has been investigated individually to test its potential for fuel conservation relative to a hypothetical baseline case in which current, in-production aircraft types are assumed to operate, without modification and with current operational techniques, into the future out to the year 2000
An Egocentric Spatial Data Model for Intelligent Mobile Geographic Information Systems
Individuals in unknown locations, such as utility workers in the field, soldiers on a mission, or sightseeing tourists, share the need for an answer to two basic questions: Where am I? and What is in front of me?Because such information is not readily available in foreign locations, aids in the form of paper maps or mobile GISs, which give individuals an all-inclusive view of the environment, are often used. This panoptic view may hinder the positioning and orienteering process, since people perceive their surroundings perspectively from their current position. In this thesis, I describe a novel framework that resolves this problem by applying sensors that gather the individual\u27s spatial frame of reference. This spatial frame of reference, in combination with an egocentric spatial data model enables an injective mapping between the real world and the data frame of reference, hence, alleviating the individual\u27s cognitive workload. Furthermore, our egocentric spatial data model allows intelligent mobile Geographic Information Systems to capture the notions of here and there, and, consequently, provides insight into the individual\u27s surroundings. Finally, our framework, in conjunction with the context given by the task to be performed, enables intelligent mobile Geographic Information Systems to implicitly answer questions with respect to where, what, and how
통행시간 신뢰도의 개별 리스크 선호도를 고려한 경로선택행태 모형
학위논문 (박사)-- 서울대학교 대학원 : 공과대학 건설환경공학부, 2018. 2. 고승영.The route choice problem is an important factor in traffic operation and transportation planning. There have been many studies to analyze the route choice behavior using travel data. There was a limit in constructing a route choice model by generating an appropriate choice set due to the limitations of the data.
In this study, we construct a choice set generation model and a stochastic route choice model using the observed data. This study estimates the parameters incorporating travelers heterogeneity according to the choice set from the choice set generation model and the route choice model.
We define the individual confidence level according to perceived travel time distribution to reflect travelers heterogeneity on choice set generation model. In addition, the parameters were estimated using the mixed path-size correction logit model (MPSCL) considering the path overlapping and individual risk preference in the route choice model.
We compare the experienced paths and the derived choice set to construct choice set generation model. In addition, it is possible to estimate better parameters incorporating travelers heterogeneity for choice set generation model and route choice model. We compare the choice set from the developed model with that of the conventional choice set generation model. This study shows the superior prediction result in route choice model reflecting the individual behaviors of the route choice in the urban area on the transportation demand forecasting and traffic operation.1. Introduction 1
1.1 Backgrounds 1
1.2 Research Purpose 4
1.3 Main contents 5
1.4 Research Scope 9
2. Literature Review 11
2.1 Choice Set Generation 13
2.2 Route Choice Model 30
2.3 Review result and limitation 58
2.4 Research Contributions 62
3. Modelling Framework 66
3.1 Overview 66
3.2 Terminology 68
3.3 Choice set generation model 76
3.4 Route choice model 92
4. Revealed Preference Routing Data 100
4.1 Data Characteristics 100
4.2 Data Collection & Description 106
4.3 Data Processing 109
4.4 Missing Data Correction 113
5. Model Estimation & Validation 120
5.1 Overview 120
5.2 Choice set generation 121
5.3 Model estimation & Validation 124
5.4 Model verification 135
5.5 Discussion 138
6. Conclusion 140
6.1 Conclusion 140
6.2 Further research 142
REFERENCES 145
APPENDIX 158Docto
Dynamic route choice in hurricane evacuation
In this research a framework is developed for modeling route choice in hurricane evacuation. Two behavioral hypotheses are evaluated which together with the route choice model, constitute the contributions of the research. The first hypothesis states that beside congestion, other variables such as familiarity with the route, availability of fuel and shelter, facility class, and length of route have an effect on an evacuees\u27 route choice. The second hypothesis states that as time passes and storm conditions change, the impact each variable has on route choice changes. The logit structure was used for modeling the choice process and stated choice data previously collected from the New Orleans area on hypothetical storms was used to calibrate the model. The study found that accessibility of a route, familiarity with a route, facility class, length of a route, and availability of services (gas stations and hotels) had an effect on evacuation route choice. The magnitude of the coefficients of perceived service, accessibility, and distance differed among those evacuating in the first half of the evacuation period versus those that evacuated in the second half but coefficients of facility class were not significantly different between two time intervals. Observed traffic count data from hurricane Katrina evacuation was used to validate the model. Comparison of traffic volumes predicted by the model with actual traffic volumes from hurricane Katrina shows error percentages of 17.5, 0.01, and 28 percent of error for volumes on I-10, I-55, and US-61 respectively
Estimating Time-Varying Origin-Destination Flows from Link Traffic Counts
A dynamic model for estimating real-time origin-destination flows from time-series of traffic counts is presented. The time variation of flows is explicitly treated as a dynamic process. The model is formulated based on minimizing the integrated squared error between predicted and observed output traffic counts over the period of observation. An efficient solution method is developed by using Fourier transformation and illustrated with numerical examples. The numerical simulation experiment shows that the system dynamic approach may be particularly suitable for on-line traffic management and control in urban transportation systems
Development and test of dynamic congestion pricing model
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Includes bibliographical references (p. 129-137).Dynamic congestion pricing is an approach to control the traffic flow on the network by setting variable tolls that are adjusted with time based on the traffic condition. Different models have been developed and tested in the past. However, most of these models are based on deterministic network equilibrium rather than stochastic choices of travelers, and case studies on complex networks are rare. These disadvantages limit the use of existing models. In this research, a new dynamic congestion pricing model is developed based on a discrete choice framework to capture users' personal choices. Several solution algorithms are examined and tested in a synthetic network for solving this model. Among these algorithms, SPSA is found to be the best, and is applied successfully to a real case study in Lower Westchester County in New York State. The usefulness and effectiveness of dynamic congestion pricing is also examined and discussed. The results show that dynamic congestion pricing has the potential to improve network performance.by Shunan Xu.S.M
Analytical Models in Rail Transportation: An Annotated Bibliography
Not AvailableThis research has been supported, in part, by the U.S. Department of Transportation under contract DOT-TSC-1058, Transportation Advanced Research Program (TARP)
Threats and countermeasures for network security
In the late 1980's, the traditional threat of anonymous break-ins to networked computers was joined by viruses and worms, multiplicative surrogates that carry out the bidding of their authors. Technologies for authentication and secrecy, supplemented by good management practices, are the principal countermeasures. Four articles on these subjects are presented
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