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  • Mobility and traffic research  (21)
  • 1
    Online Resource
    Online Resource
    Travel Time Distribution under Interrupted Flow and Application to Travel Time Reliability
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2466, No. 1 ( 2014-01), p. 114-124
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2466, No. 1 ( 2014-01), p. 114-124
    Abstract: The travel time distribution under interrupted flow based on radio frequency identification–detected data is analyzed. The urban road network studied is in downtown Nanjing, Jiangsu Province, in China, where video cameras and radio frequency equipment are installed at some arterial links to acquire traffic flow data including vehicle type, passing time, and spot speed. On the basis of the radio frequency identification data, the travel time distribution under interrupted flow shows a bimodal curve instead of a unimodal curve. This finding suggests that travel times under interrupted flow are not independent and identically distributed and can be divided into two components, the uninterrupted component and the interrupted component, according to whether vehicles experience intersection control delay. Six convex distribution models are presented, and an expectation–maximization algorithm is adopted to obtain the best distribution for each link unit. The results indicate that travel time under interrupted flow generally follows a bimodal distribution. The parameters of the models can distinguish travel times between those encountering delay and those without delay. This finding demonstrates that intersection control delay plays a predominant role in travel times under interrupted flow. Two main travel time reliability indexes under interrupted flow obtained by the parameters of the bimodal distribution, expected travel time and RATIO, are presented as applications. Expected travel times indicate the average levels of travel times of two independent components, and RATIO represents the ratio of the uncertain part of the travel times. The analysis indicates that these two indexes can capture the characteristics of interrupted-flow travel time reliability, which is mainly caused by link length, number of intersections, and mixed traffic flow.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2466-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 2
    Online Resource
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    Steepest Descent Day-to-Day Dynamic Toll
    SAGE Publications ; 2007
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2039, No. 1 ( 2007-01), p. 83-90
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2039, No. 1 ( 2007-01), p. 83-90
    Abstract: Day-to-day dynamic congestion pricing schemes have been recently proposed to force the traffic system to evolve from the status quo to a stationary state of system optimum instead of user equilibrium, considering drivers’ day-to-day behavior adjustments. From the perspective of traffic management, it may be desirable to expedite the evolution process such that the total travel cost across the process can be reduced. A novel steepest descent dynamic toll scheme is proposed that minimizes the derivative of the total system cost with regard to day t or reduces the total system cost the most for each day. The problem of finding the steepest descent scheme is first formulated as a piecewise linear nonsmooth optimization problem and then transformed into a standard linear programming problem. Its mathematical properties are discussed further and a solution procedure is proposed for specifying the steepest descent pricing scheme. A numerical study of the well-known Braess network and the Sioux Falls, South Dakota, network is conducted to compare the performance of different dynamic pricing schemes.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2039-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2007
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  • 3
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    Rolling Stock Allocation and Timetabling for Urban Rail Transit Network with Multiple Depots
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 11 ( 2022-11), p. 422-435
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 11 ( 2022-11), p. 422-435
    Abstract: Rolling stock management and train timetabling are two challenging but very related issues in urban rail systems. The former is to allocate a certain fleet of trains to each depot, and the latter determines the arrival and departure times of train services according to the available rolling stock at each depot. While most existing studies consider these two tasks for a single line, this study focuses on the integrated optimization of rolling stock allocation, train timetabling, and rolling stock circulation for a whole network, where each depot can serve multiple connected lines and the trains can change lines in one operational cycle (i.e., one day). A time-space network is constructed to model the rolling stock circulation among multiple lines and depots, and a novel integer linear programming model is proposed to jointly optimize the allocation of rolling stock and train timetables for the involved lines. The objective function maximizes the service quality provided to passengers with minimized rolling stock investment cost. Numerical experiments based on the real-world data of the Beijing rail transit network are conducted to validate the effectiveness of this approach. The results demonstrate that the proposed approach can reduce the fleet size of rolling stock by 5% while providing the same service quality to passengers.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221093323
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 4
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    Analyzing Passenger Travel Demand Related to the Transportation Hub inside a City Area using Mobile Phone Data
    SAGE Publications ; 2018
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2672, No. 50 ( 2018-12), p. 23-34
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2672, No. 50 ( 2018-12), p. 23-34
    Abstract: The passenger transportation hub plays a crucial role in the urban transportation system. Analyzing transportation hub related travel demand is necessary to support urban transportation planning and management. However, it is difficult to use the traditional travel survey methods to study travel demand because tracking passenger travel trajectories is a near impossible task. The location information from the cellular system provides a feasible way to solve the problem. This paper concentrates on applying mobile phone data to study passenger travel demand related to the Hongqiao transportation hub in Shanghai, China. First, a method is introduced to collect passenger travel information related to the hub from mobile phone data. Then, travel demand indexes are presented to characterize the travel demand in a visual way. Finally, transportation corridors, which connect the hub and other urban areas, are identified to analyze the distribution of travel demand more thoroughly. The results illustrate that the passenger travel demand shows an obvious tide pattern in the city area with the Hongqiao transportation hub as the center. Moreover, there are two identified transportation corridors which reveal the major distribution directions of the passengers, that is, the city center and the Zizhu industrial development zone. The approach in this study testifies that mobile phone data has great potential for transportation planning and management related to transportation hubs.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198118774671
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
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  • 5
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    Moments Analysis for Improving Decision Reliability Based on Travel Time
    SAGE Publications ; 2006
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1968, No. 1 ( 2006-01), p. 109-116
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1968, No. 1 ( 2006-01), p. 109-116
    Abstract: Decision reliability is becoming an important issue for both researchers and transportation service providers; different models and methods have been proposed to improve decision reliability. A method is proposed for improving decision reliability by analyzing the moments and central moments of historical travel time data. Because of the existence of traffic congestion—especially nonrecurrent traffic congestion—travel time is generally a random variable with an asymmetric historical distribution. Statistical methods are applied to obtain the higher-order moments and central moments of historical travel time, which provide quantitative information about the variability, asymmetry, and leptokurtosis of travel time. This information is useful in making reliable decisions and avoiding scenarios that can potentially lead to extremely high costs. The method is based on advanced traveler information systems, which provide useful historical travel time information for traffic networks. The new method and other methods are compared with two testing experiments.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198106196800113
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
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  • 6
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    Re-examining the Rank-Size Distribution, Characteristics, and Evolutionary Trends of Air Transport Flows in China
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: Understanding of air transport geography is essential since air transport activity is highly related to regional economic development. A geographical issue arises: Does Zipf’s law strike again? Zipf’s law can be an efficient tool to detect the geographical distribution of air passenger (or freight) flows. Using provincial passenger and freight traffic data from 1980 to 2019, this study adopts Zipf’s law to analyze rank-size distribution characteristics of the air transport industry in China and its evolution. We then build a Geo-Detector model to explore the driving forces of geographical distributions (of air traffic). The findings are as follows. First, the geographical distribution of aviation flows in China complies with Zipf’s law, and the freight flow is more significant than the passenger flow. From a spatial to spatial-temporal perspective, the geographical distribution of different aviation flows (i.e., air passenger and freight flows) can be more diverse. Second, critical factors like international import trade, the number of foreign business travelers, and foreign direct investment combine to shape the geographical distribution of air traffic.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231168863
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 7
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    Location-Based Social Networking Data : Exploration into Use of Doubly Constrained Gravity Model for Origin–Destination Estimation
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2430, No. 1 ( 2014-01), p. 72-82
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2430, No. 1 ( 2014-01), p. 72-82
    Abstract: Trip distribution is an invaluable portion of the transportation planning process; this distribution leads to the creation of origin–destination (O-D) matrices. Location-based social networking (LBSN) has increased in popularity and sophistication and has emerged as a new travel demand data source. Users of LBSN provide location-sensitive data interactively with mobile devices, including smartphones and tablets. These data can provide O-D estimates with significantly higher temporal resolution at a much lower cost in comparison with traditional methods. An LBSN O-D estimation model based on the doubly constrained gravity model was proposed to improve a previously proposed model based on the singly constrained gravity model. The proposed methodology was calibrated and comparatively evaluated against the O-D matrix generated by the method based on the singly constrained gravity model as well as a reference matrix from the local metropolitan planning organization. The results of this method illustrate significant improvement in reducing the O-D estimation errors caused by the sampling bias from the method based on the singly constrained gravity model.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2430-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 8
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    Influence of Frequency-Dependent Dynamic Parameters of Rail Pads on Environmental Vibration Induced by Subways in a Tunnel
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2476, No. 1 ( 2015-01), p. 8-14
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2476, No. 1 ( 2015-01), p. 8-14
    Abstract: On the basis of verification of a new frequency-domain method with measured data, the influence of frequency-dependent dynamic parameters of rail pads on environmental vibration is investigated. The contrast between theoretical and measured data shows that the new approach is reasonable and provides high accuracy. The influence of frequency-dependent stiffness of rail pads on environmental vibration can be neglected below the one-third octave frequency of 25 Hz and yet alters not only the frequency-domain amplitudes of environmental vibration but also its frequency distribution above 25 Hz. The frequency-dependent damping of rail pads slightly increases the maximum ground vibration level in one-third octave frequencies and yet reduces that of an above-the-center frequency with the maximum vibration level. Simply increasing the constant stiffness of rail pads or decreasing the constant damping can give the smallest error in the predicted ground vibration in either the low-frequency or the high-frequency domain. With continuous deterioration of track irregularity, regardless of frequency-dependent dynamic parameters of rail pads, the constant stiffness or damping of rail pads with the smallest error is not invariable.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2476-02
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
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  • 9
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    Pedestrian Injury Severities in Pedestrian-Vehicle Crashes and the Partial Proportional Odds Logit Model: Accounting for Age Difference
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 5 ( 2019-05), p. 731-746
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 5 ( 2019-05), p. 731-746
    Abstract: This study investigates factors that significantly contribute to the severity of pedestrian injuries resulting from pedestrian-vehicle crashes. Multinomial logit (MNL) models, mixed logit (ML) models, and ordered logit/probit models have been widely used in modeling crash injury severity, including pedestrian injury severity in pedestrian-vehicle crashes. However, both MNL and ML models treat injury severity levels as non-ordered, ignoring the inherent hierarchical nature of crash injury severities, and the data used in ordered logit models need to be strictly subjected to the proportional odds (PO) assumption. In this study, a partial proportional odds (PPO) logit model approach is employed to explore the issues of pedestrian safety associated with each age group: young (aged under 24), middle-aged (aged 25–55), and older pedestrians (aged over 55). Data used in this study are police-reported pedestrian crash data collected from 2007 to 2014 in North Carolina. A variety of motorist, pedestrian, environmental, and roadway characteristics are inspected. Results from likelihood ratio tests statistically show the better performance of developing separate injury severity models for each age group compared with estimating a single model utilizing all data. Relevant parameter estimates and associated marginal effects are used to interpret the results, followed by recommendations made in the concluding section.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119842828
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 10
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    Modeling Vehicle Interactions during Merge in Congested Weaving Section of Freeway Ramp
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2421, No. 1 ( 2014-01), p. 82-92
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2421, No. 1 ( 2014-01), p. 82-92
    Abstract: One major limitation of existing microscopic traffic simulation models is the lack of data about vehicle interactions during the lane-changing process in congested merging areas. The interactions between vehicles during lane changing in the congested weaving sections are quantified. A series of acceleration-deceleration models was developed for the merging vehicle, its putative leader (PL), and its putative follower (PF). After US-101 data were analyzed, the yielding behavior of the merging vehicle's PL for merging cooperation and the lateral separation between vehicles in the weaving section (features largely ignored in previous research) were introduced into the proposed acceleration—deceleration models, and visual angle data were used as the stimuli to reflect the influence of longitudinal and lateral vehicle movements. Car-following behavior was incorporated into the model (e.g., the PF gradually changed its car-following leader from the PL to the merging vehicle, dependent on relative vehicle locations). Calibrated and validated with FHWA's next generation simulation (NGSIM) program trajectory data, the proposed acceleration-deceleration models could qualitatively simulate the behavior of drivers in lane-changing maneuvers with acceptable training and testing errors. To verify the cooperative behavior of the PL in lane changing, the proposed PL acceleration-deceleration model was compared with a base car-following model. Results indicate that incorporating the effects of the merging vehicle on the PL can enhance the realism of a lane-changing model. Findings from this study can contribute to the understanding of interactions between vehicles during complex lane-changing processes.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2421-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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