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  • Mobility and traffic research  (12)
  • 1
    Online Resource
    Online Resource
    Enhancing Traffic Incident Detection by Using Spatial Point Pattern Analysis on Social Media
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2528, No. 1 ( 2015-01), p. 69-77
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2528, No. 1 ( 2015-01), p. 69-77
    Abstract: Expedient incident detection and understanding are important in traffic management and control. Social media as important information venues have immense value for increasing an awareness of traffic incidents. In this paper, an attempt is made to assess the potential of using harvested social media for traffic incident detection. Twitter in Seattle, Washington, was chosen as a representative sample environment for this work. A hybrid mechanism based on latent Dirichlet allocation and document clustering was proposed to model incident-level semantic information, while spatial point pattern analysis was applied to explore the spatial patterns and to assess the spatial dependence between incident-topic tweets and traffic incidents. A global Monte Carlo K-test indicated that the incident-topic tweets were significantly clustered at different scales up to 600 m. The nearest neighbor clutter removal method was used to separate feature tweet points from clutter; then a density-based algorithm successfully detected the clusters of tweets posted spatially close to traffic incidents. In multivariate spatial point pattern analysis, K-cross functions were investigated with Monte Carlo simulation to characterize and model the spatial dependence, and a positive spatial correlation was inferred between incident-topic tweets and traffic incidents up to 800 m. Finally, the tweet intensity as a function of distance from the nearest traffic incident was estimated, and a log-linear model was summarized. The experiments supported the notion that social media feeds acted as sensors, which allowed enhancing awareness of traffic incidents and their potential disturbances.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2528-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    On Missing Traffic Data Imputation Based on Fuzzy C -Means Method by Considering Spatial–Temporal Correlation
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2528, No. 1 ( 2015-01), p. 86-95
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2528, No. 1 ( 2015-01), p. 86-95
    Abstract: The lack of some traffic flow data seriously affects the quality of data collection and analysis in the traffic system. Completing the missing data is one of the most important steps in achieving the functions of intelligent transportation systems. In this paper an approach based on fuzzy C-means (FCM) imputes missing traffic volume data in loop detectors. With spatial–temporal correlation between detectors, the conventional vector-based data structure is first transformed into a matrix-based data pattern. Then, the genetic algorithm is applied to optimize the parameters of cluster size and weighting factor in the FCM model. Finally, the actual traffic flow volume collected at different locations is designed as a testing data set, and two indicators including root mean square error and relative accuracy are used to evaluate the imputation performance of the proposed method by comparison with some conventional methods (multiple linear regression, autoregressive integrated moving average model, and average historical method) by missing ratio. The applications in four scenarios demonstrate that the FCM-based imputation method outperforms conventional methods.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2528-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
    detail.hit.zdb_id: 2403378-9
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  • 3
    Online Resource
    Online Resource
    How Does Ride-Hailing Influence Individual Mode Choice? An Examination Using Longitudinal Trip Data from the Seattle Region
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 3 ( 2022-03), p. 621-633
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 3 ( 2022-03), p. 621-633
    Abstract: This study investigates the impacts of ride-hailing, which we define as mobility services consisting of both conventional taxis and app-based services offered by transportation network companies, on individual mode choice. We examine whether ride-hailing substitutes for or complements travel by driving, public transit, or walking and biking. The study overcomes some of the limitations of convenience samples or cross-sectional surveys used in past research by employing a longitudinal dataset of individual travel behavior and socio-demographic information. The data include three waves of travel log data collected between 2012 and 2018 in transit-rich areas of the Seattle region. We conducted individual-level panel data modeling, estimating independently pooled models and fixed-effect models of average daily trip count and duration for each mode, while controlling for various factors that affect travel behavior. The results provide evidence of substitution effects of ride-hailing on driving. We found that cross-sectionally, participants who used more ride-hailing tended to drive less, and that longitudinally, an increase in ride-hailing usage was associated with fewer driving trips. No significant associations were found between ride-hailing and public transit usage or walking and biking. Based on detailed travel data of a large population in a major U.S. metropolitan area, the study highlights the value of collecting and analyzing longitudinal data to understand the impacts of new mobility services.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211055669
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2403378-9
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  • 4
    Online Resource
    Online Resource
    Temporal Geographic Information System and Its Application to Transportation
    SAGE Publications ; 1997
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1593, No. 1 ( 1997-01), p. 47-54
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1593, No. 1 ( 1997-01), p. 47-54
    Abstract: While geographic information systems (GIS) have proven to be powerful tools that are capable of storing, displaying, and analyzing spatially distributed information, current GIS lack adequate capabilities for handling temporal information. As a result, analyses are mostly performed assuming a fixed time point. Longitudinal analyses that take time into consideration cannot be easily accomplished. For many applications, information constantly changes in both space and time. A temporal GIS, one that is capable of handling temporal as well as spatial information, will greatly expand the current GIS applications and allow new information to be obtained. Some preliminary results are presented of an ongoing study of a temporal GIS. To explore the problems and potential benefits of a temporal GIS, a simple method has been developed to record the changes in spatial objects for time using personal computer ARC/INFO relational databases as well as a set of commands to query the spatiotemporal data. The use of this temporal GIS method is illustrated using an example of transit service analysis.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1593-07
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1997
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  • 5
    Online Resource
    Online Resource
    Improved Computational Framework for Efficient Bayesian Probabilistic Inference of Damage in Truss Structures Based on Vibration Measurements
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2460, No. 1 ( 2014-01), p. 117-127
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2460, No. 1 ( 2014-01), p. 117-127
    Abstract: This paper presents a computationally efficient Bayesian inference framework and its application to infer damage in truss bridges. The novelty of the proposed framework for reducing the computational burden of Bayesian inference of structural damage lies in ( a) the revised transitional Markov chain Monte Carlo algorithm for efficiently drawing statistical samples of damage indexes and ( b) the likelihood function in the frequency domain based on modal properties that could be derived from the stochastic subspace identification. Other special features of the proposed framework include ( a) explicitly modeling complexities of truss joints for allowing identification of truss joint damage and the assessment of its associated uncertainties and ( b) incorporating the structural finite element model into the probabilistic inference computational environment through the program application interface. Those improvements make new contributions to the field of damage identification for truss bridges, leading to the practical application of Bayesian inference of the large amounts of potential damage not only in truss members but also in truss joints. The applicability and efficiency of the proposed framework are illustrated and examined by using numerical simulation of a damaged prototype truss structure. Simulation results indicate that the proposed approach has the potential capacity for determining the extent and location of large amounts of truss damage and the probabilistic characteristics. Finally, the limitation of this study and the future research need for practical application of the proposed probabilistic framework are discussed.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2460-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
    detail.hit.zdb_id: 2403378-9
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  • 6
    Online Resource
    Online Resource
    Quantitative Assessment of the Pavement Modulus and Surface Crack using the Rayleigh Wave Dispersion Curve
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 5 ( 2020-05), p. 259-269
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 5 ( 2020-05), p. 259-269
    Abstract: Surface cracks directly influence the integrity of asphalt pavement structures, the durability of the pavement, and driving safety. Assessment of cracking distress is of vital importance for pavement maintenance and rehabilitation. Compared with other methods, the spectral analysis of surface waves (SASW) method, a seismic wave-based nondestructive method, has advantages in estimating the deterioration of modulus and quantitatively evaluating the depth and severity of surface cracks by means of the Rayleigh wave propagation characteristic. The objectives of this paper are to monitor long-term attenuation characteristics of in-situ modulus of a semi-rigid asphalt pavement, to determine when the surface-opening cracks will occur as associated to the degree of modulus reduction, and to assess the depth of surface-opening crack through the dispersion characteristics of Rayleigh wave propagation using the SASW method. First, a general trend of modulus deterioration of asphalt layer was developed in an accelerated pavement testing (APT). Then the factors affecting the dispersion characteristics of the Rayleigh wave were determined through theoretical derivation. Finally, a series of experimental tests on a pavement segment with well-controlled surface-opening cracks was performed to explore how a surface-opening crack in asphalt pavement would vertically influence the propagation of Rayleigh waves at different crack widths. It was found that the general trend of modulus deterioration could be divided into four stages, and the surface-opening cracks occurred in the fourth stage with 40–50% modulus reduction rate. In addition, the relationship between crack depth and the shortest wavelength in the Rayleigh wave dispersion curve was developed according to different crack widths.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120913856
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
    detail.hit.zdb_id: 2403378-9
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  • 7
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    Online Resource
    Meso-Scale Kinematic Responses of Asphalt Mixture in Both Field and Laboratory Compaction
    SAGE Publications ; 2021
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2675, No. 9 ( 2021-09), p. 1631-1642
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2675, No. 9 ( 2021-09), p. 1631-1642
    Abstract: Compaction is one of the most critical steps in asphalt pavement construction. Traditional compaction relies heavily on engineering experience and post-construction quality control and can lead to under/over compaction problems. The emerging intelligent compaction technology has improved compaction quality but is still not successful in obtaining mixture properties of a single pavement layer. Besides, very few studies have discussed the internal material responses during field and laboratory compaction to explain the meso-scale (i.e., particle scale) compaction mechanism. Knowledge in those areas may greatly promote the development of smart compaction. Therefore, this study aims to investigate the kinematic behavior of the asphalt mixture particles (translation and rotation) under six types of field and laboratory compaction methods and establish the relationship between the field and the laboratory compaction by using a real-time particle motion sensor, SmartRock. It was found that particle movement pattern was mainly affected by the compaction mode. At the meso-scale where particle behavior is the focus, the kneading effects of a pneumatic-tire roller can be simulated by laboratory gyratory and rolling wheel compaction, and the vibrating effects of a vibratory roller can be simulated by Marshall compaction. However, none of those laboratory compaction methods can completely simulate the field compaction. Under vibratory rolling, particle acceleration decreased fast in the breakdown rolling stage. Under pneumatic-tire rolling, particle angular position change was related to aggregate skeleton, and particle relative rotation showed a decreasing trend that was consistent with the laboratory gyratory compaction results. Those kinematic responses can potentially be used to monitor density change in field compaction.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211009222
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
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  • 8
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    Online Resource
    Trajectory Data Processing and Mobility Performance Evaluation for Urban Traffic Networks
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 3 ( 2023-03), p. 355-370
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 3 ( 2023-03), p. 355-370
    Abstract: With the rapid development and deployment of vehicle sensing and communication technology, vehicle trajectory data is becoming increasingly available for urban traffic network applications. However, it is difficult to use raw trajectory data points generated from global navigation satellite system (GNSS) coordinates without matching them to traffic networks. Real-world trajectory data is also prone to noise and errors. This paper proposes a trajectory data processing pipeline to serve different urban traffic network applications. The steps of the pipeline include matching the trajectory points to a well defined network representation, splitting them into different movements, and extracting distance information from their GNSS coordinates. Smoothing and filtering algorithms also reduce the influence of noise and errors. Based on the processed trajectory data, this paper also proposes algorithms for calculating different mobility performance indices including vehicle delay, number of stops, space-mean speed, and coordination measurements. These performance indices provide comprehensive evaluations of urban traffic network from different perspectives. Our case study uses real-world trajectory data collected from the Ann Arbor Connected Vehicle Test Environment. Different mobility performance indices are calculated and visualized. The proposed methods and algorithms are efficient, robust, and scalable, and could be applied to large-scale urban traffic networks.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221115088
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 9
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    Online Resource
    Blending Efficiency and Effective Styrene Butadiene Rubber Concentration of Micro-Surfacing Mixtures with Reclaimed Asphalt Pavement
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 5 ( 2020-05), p. 47-58
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 5 ( 2020-05), p. 47-58
    Abstract: Reclaimed asphalt pavement (RAP) has been used in micro-surfacing mixtures with good promise and improved sustainability. However, no systematic study has been conducted to analyze the chemical components of the RAP micro-surfacing mixture when blending virgin binder with RAP binder, and to confirm the reasonableness of using RAP micro-surfacing mixtures. Based on a gap-graded method, this paper explored the chemical properties of RAP micro-surfacing mixtures using attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) and fluorescence microscopy, and explained the blending mechanism between the RAP and the cold mixture. The blending efficiency and effective styrene butadiene rubber (SBR) concentration were quantified based on various chemical component parameters. The results showed that partial blending existed for RAP micro-surfacing mixtures. It was found that the diffusion happened from the outer layer of the RAP mixture as a result of the coating of emulsion, and could continuously and gradually happen for the RAP mixture, giving higher blending efficiency for a high RAP content mixture. The addition of RAP makes SBR particles more dispersible. Including rejuvenators and increasing curing time could improve the blending efficiency and the effective modifier concentration.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120914616
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 10
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    Online Resource
    System-Level Fault Prognosis for High-Speed Railway On-Board Systems
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 12 ( 2019-12), p. 584-595
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 12 ( 2019-12), p. 584-595
    Abstract: The on-board system is the core part of a train control system that ensures traffic safety and improves operational efficiency. At present, fault data processing methods for on-board systems do not show the degradation of components, subsystems, or the system over time, but only focus on identifying faults after a failure has occurred, so fault prognosis cannot be realized. This paper applies a multilevel flow model based on system-level failure mode and effect analysis. The model defines the primary and secondary alarms, divides the failure modes into different levels, and ranks the risk priority numbers at different levels. The Balise transmission system is then used as an example to demonstrate the system-level fault prognosis methodology, and the variables from different levels are combined through the component model, subsystem model, and system model. The results are verified according to the actual operation manual.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119867673
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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