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  • Mobility and traffic research  (16)
  • 1
    Online Resource
    Online Resource
    Non-Symmetric Spatial-Temporal Network for Bus Origin–Destination Demand Prediction
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 2 ( 2022-02), p. 279-289
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 2 ( 2022-02), p. 279-289
    Abstract: Urban public transport has become a preferred choice for alleviating traffic congestion. The bus passenger OD (origin–destination) demand prediction based on bus operational data is the key technology to realize urban intelligent transportation system. However, most of the existing bus OD demand prediction methods only considered regional passengers. The problem of the OD demand prediction based on historical OD matrices of bus lines is still not easy to implement, exceptionally, which is suitable for most of the urban bus lines. This paper presents a non-symmetric spatial-temporal network (NSTN) based on convolutional neural network (CNN) and convolutional long short-term memory (ConvLSTM) network to predict bus OD. NSTN contains the station spatial component (SSC) module and the spatial-temporal component (STC) module. SSC consists of two CNNs to learn the OD features and the DO (destination-origin) features, respectively. To make the prediction shift to the OD features, the non-symmetric input is designed. STC extracts spatial-temporal features based on ConvLSTM. Compared with other methods, NSTN has the best performance measured by symmetric mean absolute percentage error (SMAPE) and root mean square error (RMSE), where its SMAPE falls by 4.3 percentage points to 16.4 percentage points and RMSE falls by 23.1 percentage points to 69.9 percentage points. Experimental results on other bus lines show that NSTN has strong generalization ability.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211039844
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 2
    Online Resource
    Online Resource
    Routing Optimization of Regional Flexible Transit Under the Mixed Demand Mode
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 10 ( 2023-10), p. 662-675
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 10 ( 2023-10), p. 662-675
    Abstract: To meet trip demands and avoid transit capacity waste or shortages, this study investigates the routing optimization of flexible transit with time windows. We introduce the time penalty costs to accommodate the impacts of early and late vehicle arrivals on passengers’ satisfaction. A routing optimization model is developed to minimize the system operation costs and the costs incurred by passengers' time penalties. The problem is solved by a designed adaptive genetic algorithm that adopts an adaptive mutation strategy to dynamically adjust the mutation probability and mutation operator. The numerical experiments compare the results of the mixed demand model, in which vehicles can pick up and drop off passengers simultaneously, to those of the separate pick-up and delivery modes. Finally, a sensitive analysis is conducted to explore the impact of operational factors (vehicle speed, maximum one-way travel time, and weighting ratios between operating and penalty costs) on the system's performance (total costs, per capita mileage, and average seat occupancy rate). Our results confirm the advantages of the developed adaptive genetic algorithm over traditional ones with respect to the convergence speed and optimality gap. Moreover, the numerical results indicate that the mixed demand operation mode of transit reduces total costs by an average of 2.35% compared to separate pick-up and delivery modes. The results also reveal that an increase in the weights of the operating cost can reduce the total cost. The findings of this work can provide guidance to the operation of regional flexible transit.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231162600
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    Exploring Criteria for Assessing the Severity of Oil Spills
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 2 ( 2019-02), p. 252-262
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 2 ( 2019-02), p. 252-262
    Abstract: Considering the characteristics of the real-time assessment of oil spill severity, this study, by reference to grounded theory and classical statistical methods, proposed a text and data mining model to obtain criteria for assessing oil spill severity. The application of the text and data mining model in the experimental case/scenario, which is designed based on historical data of oil spills in a specific region and those recorded in Lloyd’s casualty database, demonstrated that the proposed model is feasible, universally applicable and requires low overhead. In actual practice, data obtained from casualty investigation reports and casualty databases can be considerably incomplete. Improving the completeness and accuracy of accident data is crucial for the further effective use of the text and data mining model in accident-related research.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198118821902
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 4
    Online Resource
    Online Resource
    Behavior of Riders of Electric Bicycles at Onset of Green and Yellow at Signalized Intersections in China
    SAGE Publications ; 2012
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2317, No. 1 ( 2012-01), p. 85-96
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2317, No. 1 ( 2012-01), p. 85-96
    Abstract: In most Chinese cities, electric bicycles and electrically assisted bicycles (e-bikes) have drastically increased in recent years and currently constitute the largest proportion of the nonmotorized traffic at signalized intersections. Proper treatment of e-bikes has become a vitally important issue in improving the operational efficiency and safety performance of signalized intersections. However, fundamental knowledge of the unique operating characteristics and behavior of riders of e-bikes under various conditions is insufficient. This study statistically analyzed critical behavioral parameters of e-bike riders and empirically modeled their start-up behavior at the green onset following a 3-s red-and-yellow signal and their stop–pass decision behavior at the yellow onset following a 3-s flashing green. Distribution types and parameters of desired speed, start-up time, acceleration rate, perception–reaction time, and deceleration rate were investigated with the use of highly accurate trajectory data. A temporal–spatial model was developed to interpret the start-up curve, and three binary logistic regression models were built to predict the stop–pass decisions for different rider groups. It was found that the start-up curve of e-bikes could be well described by a quadratic function and that the red-and-yellow signal significantly induced a hurried start. The potential time to the stop line at the decision point was found to be the dominant independent factor explaining the stop–pass decision of e-bike riders; the flashing green signal seemed to enlarge the option zone, bring the indecision zone earlier, and result in more aggressive passing behavior.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2317-11
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2012
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  • 5
    Online Resource
    Online Resource
    Influence of Carbon Nanotubes on Morphology of Asphalts Modified with Styrene–Butadiene–Styrene
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2632, No. 1 ( 2017-01), p. 130-139
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2632, No. 1 ( 2017-01), p. 130-139
    Abstract: The main challenge of asphalt modified with styrene–butadiene–styrene (SBS) during storage and application is the phase separation of SBS-rich phases and asphaltene-rich phases. These phases have a close relationship with the morphology of SBS-modified asphalt [SBS–polymer-modified binders (PMBs)]. Carbon nanotubes (CNTs) were selected in this paper to provide different morphology of SBS-PMBs with CNTs. The morphology was composed of SBS-rich phases, asphaltene-rich phases, and their interphase, captured from fluorescence microscopy (FM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The components and morphologies of the interface on a molecular scale were obtained by molecular dynamic simulation. The results from FM images showed an increase in the relative content of SBS-rich phases as the amount of CNTs increased, highlighting CNTs’ positive role in the compatibility of SBS and asphalt. Mixing CNTs with a mechanical stirrer provided a larger size of SBS-rich phases than that of SBS-PMBs in AFM images using an ultrasound performed on an interpenetration network of AFM and FM images, whereas mixing with an extruding machine resulted in an orange-skin morphology in FM images. The results from SEM demonstrated that CNTs changed the interface of SBS-PMBs by pullout behaviors. The results from the molecular dynamic simulation showed that SBS intertwined or surrounded CNTs to improve their interaction. Saturate, aromatic, and resin were absorbed into the tube of CNTs. Therefore, CNTs had a positive action on the interaction between SBS and asphalt because they acted as a bridge to link the different phases, finally reinforcing the interface of SBS-PMBs.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2632-14
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 6
    Online Resource
    Online Resource
    Analysis of Pedestrian–Vehicle Traffic Conflicts in Street Designs with Elements of Shared Space
    SAGE Publications ; 2013
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2393, No. 1 ( 2013-01), p. 21-30
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2393, No. 1 ( 2013-01), p. 21-30
    Abstract: Changes in pedestrian–vehicle traffic conflicts in urban streets redesigned according to the principles of shared space were investigated with a recently developed pedestrian–vehicle conflict analysis (PVCA) method. In a first step, the PVCA method was revised to reflect more accurately the features of shared space; this revision included the definition of a systematic process for identifying conflict occurrences on the one hand and the full quantification of the conflict severity grading process on the other. Then the refined PVCA method was applied to a case study in London with video data from periods before and after the redevelopment of the Exhibition Road site from a conventional dual carriageway to a modern design with some elements of shared space. The results of the comparative analysis indicated a general decrease in traffic conflict rates as a result of the redesign but also highlighted specific issues that may require additional analysis.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2393-03
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
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  • 7
    Online Resource
    Online Resource
    Understanding the Multimodal Evacuation Behavior for a Near-Field Tsunami
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 11 ( 2019-11), p. 480-492
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 11 ( 2019-11), p. 480-492
    Abstract: This paper presents an agent-based tsunami evacuation modeling (ABTEM) framework in Netlogo to analyze the impact of various multimodal evacuation behaviors on life safety for a near-field tsunami. The objective of this work is to investigate how: milling time, choice of modes (i.e., walking and automobile), and critical variables involved in an evacuation scenario (e.g., walking, driving speed), affect life safety. Using the city of Seaside, Oregon, which is one of the most vulnerable cities on the Oregon coast, as a study site, different evacuation scenarios are included in the model to assess the impact of parameters involved on the mortality rate in a tsunami evacuation event. The results show that: choice of evacuation mode strongly and non-linearly influences the expected number of casualties; use of vehicles leads to the creation of congestion and bottlenecks, and thus, higher mortality rate; the mortality rate is strongly correlated with milling time; and the mortality rate is sensitive to the variations in average walking speed of the population. The results will help emergency managers, community leaders, and city and state agencies in their decision-making process for creating effective and efficient evacuation plans to increase life safety and community resilience.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119837511
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 8
    Online Resource
    Online Resource
    Relationship between Overconfidence and Risky Behavior among Ship Crew
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 9 ( 2020-09), p. 500-510
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 9 ( 2020-09), p. 500-510
    Abstract: Human factors are a primary cause of maritime accidents. This paper explores the relationship between risky behavior and overconfidence among members of a ship crew. Data on confidence and risky behaviors were collected through experiments carried out on a navigation simulator and an associated questionnaire. Contingency table analysis and chi-square test were then performed to clarify the relationships between these variables. The results indicated that both overconfidence and underconfidence were potential causes of risky behaviors among crew members; the type of risky behavior undertaken was also found to be related to both overconfidence and underconfidence. Levels of confidence varied with individual characteristics such as age and sailing experience. The major findings were as follows. Crew members aged 25 years or younger were more likely to be overconfident; crew members with less sailing experience were more likely to be either highly overconfident or underconfident; highly overconfident and underconfident crew members were more prone to involvement in collisions; skill-based risky behaviors were most associated with underconfidence; rule-based risky behaviors were more likely to be exhibited by highly overconfident or underconfident crew members; knowledge-based risky behavior was primarily observed in highly overconfident crew members. This paper fills a current research gap by identifying the individual characteristics that induce risky behaviors, which will be beneficial in enabling the maritime sector to develop targeted interventions to prevent maritime accidents.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120930008
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 9
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    Online Resource
    Optimizing Right-Turn Signals to Benefit Pedestrian–Vehicle Interactions
    SAGE Publications ; 2021
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2675, No. 8 ( 2021-08), p. 22-33
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2675, No. 8 ( 2021-08), p. 22-33
    Abstract: In most right-driving urban signalized intersections, right-turn vehicle signals do not usually control turns. To address the problem of signal control in a pedestrian–vehicle interaction, this paper establishes a right-turn signal optimization (RTSO) model that considers both efficiency and safety. First, the main factors influencing the behavior of vehicle and pedestrian during pedestrian–vehicle interaction are analyzed, and a pedestrian–vehicle interaction model (PVI model) at an urban road crosswalk is established. This model is used to determine the probabilities of four pedestrian–vehicle interaction situations. Then, based on the traffic conflict theory, the next step was to construct an objective function that minimizes the total delay of traffic participants considering pedestrian–vehicle interactions, and another objective function that minimizes the potential conflicts considering pedestrian–vehicle interactions. Then, an RTSO model is obtained by introducing a safety-efficiency coefficient to combine the previously described two constructed functions. Finally, the PVI model and delay model are verified through video observation data and the establishment of a cellular automata simulation platform of pedestrian–vehicle interaction. Using these models, a field signal plan, the delay minimization scheme, the conflict minimization scheme, and the proposed scheme are numerically analyzed under different yielding rates. This proposed scheme is further numerically analyzed under different safety-efficiency coefficients. The results show that this paper’s RTSO model has certain advantages in increasing safety and reducing delay. In addition, using these results, this paper gives a recommended value for the safety-efficiency coefficients in different application scenarios.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198121995511
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
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  • 10
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    Online Resource
    Speed Modeling and Travel Time Estimation Based on Truncated Normal and Lognormal Distributions
    SAGE Publications ; 2012
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2315, No. 1 ( 2012-01), p. 66-72
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2315, No. 1 ( 2012-01), p. 66-72
    Abstract: Travel time is a vital performance index in assessing transportation network performance. Vehicle speeds along any network route fluctuate, and route travel times are essentially random. This technical note first examines travel time modeling and estimation with the random modeling of speeds, and then a general approach is presented for travel time estimation based on speed distributions. Because normal and lognormal distributions are commonly employed for speed modeling in traffic engineering, travel time estimation is further discussed concerning distributions. Most probability distributions (including normal and lognormal) assume that a modeled random variable spreads over the whole or half-range of the real number axis, but in practice, any traffic quantity of interest makes sense only within a limited value range. The concept of truncated distributions is introduced, and specifically, the probability features of truncated normal and lognormal distributions are explored concerning the discussed travel time estimation issue.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2315-07
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2012
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