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  • Mobility and traffic research  (8)
  • 1
    Online Resource
    Online Resource
    Acceleration Characteristics at Metered On-Ramps
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2484, No. 1 ( 2015-01), p. 1-9
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2484, No. 1 ( 2015-01), p. 1-9
    Abstract: Vehicle acceleration capability is an important parameter for traffic operation analysis, traffic simulation, and transportation facilities design. Most of the existing studies on acceleration characteristics, however, do not fully represent the realistic traffic conditions or are based on outdated data; these deficiencies may result in errors in modeling vehicle acceleration capability. In this paper, actual acceleration characteristics at metered on-ramps were investigated according to field data collection and analysis. With the assumption that vehicles make uniformly accelerated motion in each short space or time interval, the entire acceleration length was partitioned into several short segments. Then, video cameras, magnetic counters, or both were used to document the spot speed at predetermined locations; accordingly, distance–acceleration profiles of various ramp configurations were determined. Results showed that the acceleration rate at metered on-ramps was not constant; vehicles usually accelerated at a higher acceleration rate when the speed was lower and vice versa, and the maximum acceleration rate usually occurred at about 50 to 100 ft downstream from the stop bar. Also, a ramp with taper merging configuration usually produced higher acceleration rates than did a parallel merging ramp. This study also pointed out that acceleration rates documented in the AASHTO Green Book, widely used by most state departments of transportation in the United States as the acceleration length design guidance for metered on-ramps, were much lower than the values measured at existing metered on-ramps.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2484-01
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    Fast-Spherical-Projection-Based Point Cloud Clustering Algorithm
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 6 ( 2022-06), p. 315-329
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 6 ( 2022-06), p. 315-329
    Abstract: Roadside LiDAR (light detection and ranging) is a solution to fill in the gaps for connected vehicles (CV) by detecting the status of global road users at transportation facilities. It relies greatly on the clustering algorithm for accurate and rapid data processing so as to ensure effectiveness and reliability. To contribute to better roadside LiDAR-based transportation facilities, this paper presents a fast-spherical-projection-based clustering algorithm (FSPC) for real-time LiDAR data processing with higher clustering accuracy and noise handling. The FSPC is designed to work on a spherical map which could be directly derived from the instant returns of a LiDAR sensor. A 2D-window searching strategy is specifically designed to accelerate the computation and alleviate the density variation impact in the LiDAR point cloud. The test results show the proposed algorithm can achieve a high processing efficiency with 24.4 ms per frame, satisfying the real-time requirement for most common LiDAR applications (100 ms per frame), and it also ensures a high accuracy in object clustering, with 96%. Additionally, it is observed that the proposed FSPC allows a wider detection range and is more stable, tackling the surge in foreground points that frequently occurs in roadside LiDAR applications. Finally, the generality of the proposed FSPC indicates the proposed algorithm could also be implemented in other areas such as autonomous driving and remote sensing.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221074365
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 3
    Online Resource
    Online Resource
    Streamlined Hierarchical Topology Network-Based Passenger Flow Assignment of Urban Rail Transit
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 8 ( 2022-08), p. 683-696
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 8 ( 2022-08), p. 683-696
    Abstract: In urban rail transit systems, passenger flow assignment is vital for administrators and designers. Many approaches using evaluation indicators seek to improve assignment accuracy. However, such approaches suffer from the inefficiency in traffic flow computation, especially in large-scale networks. K-shortest path searching is an essential component in flow assignment; its complexity depends on the network scale. This study proposes a simplified framework with a bi-layer network (BL-NSF) to find the K-shortest path as early as possible to improve the speed of flow assignment while meeting accuracy requirements. First, a bi-layer transformation operator is developed. Specifically, a first-layer transformation operator employs the station extraction function to simplify the type of stations. The network is, therefore, first reduced since non-transfer stations are extracted. Second, a second-layer transformation operator with a path filter function is designed to eliminate the non-effective connection structure. Thus, the complexity of the network is further reduced, and the streamline structure of the topology rail network is constructed. Sequentially, we search the K-shortest path by executing four designed matching mechanisms and a modified Yen’s algorithm, a traditional algorithm used in the existing transit system. After that, we perform passenger flow calculations for stations, links, and lines. Finally, a series of experiments is run on the test network to verify the effectiveness and efficiency of BL-NSF on the flow assignment. The results demonstrate that the proposed BL-NSF performs better and is more competitive than the state-of-the-art algorithms.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221084689
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 4
    Online Resource
    Online Resource
    Curbside Parking Monitoring With Roadside LiDAR
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 10 ( 2023-10), p. 824-838
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 10 ( 2023-10), p. 824-838
    Abstract: Cities worldwide are striving to find more efficient approaches to address the prevalent parking challenges in urban areas. A key aspect of achieving an optimal parking environment is the collection of curbside parking data, which enables informed decision-making and effective management of on-street parking spaces. This study proposes a solution for curbside parking monitoring and data collection using roadside LiDAR systems. By leveraging laser beam variation detection, this solution can extract essential information about parking usage. Unlike existing solutions, such as imagery or embedded sensor-based monitoring, our solution offers portability and ease of deployment for short-term or long-term curbside parking data collection. Additionally, the LiDAR sensor captures only three-dimensional data and is independent of illumination conditions, ensuring stable operation throughout the day while safeguarding privacy by not capturing imagery. These features align with the requirements of city agencies for parking data collection. The workflow follows a simple trend without the need for complex training, as typically seen in machine learning-based methods, and instead relies on parameter tuning based on real-world environmental factors. To validate the effectiveness of our method, we collected curbside parking data for five days at a midtown traffic junction with eight parking spaces. Manual validation confirmed a 95% match between identified parking events and observed data across different time periods. The study further presents parking statistics based on the identified events, revealing crucial insights about parking usage in the study area.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231193410
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 5
    Online Resource
    Online Resource
    Mechanistic Modeling and Economic Analysis of Piezoelectric Energy Harvesting Potential in Airport Pavements
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 11 ( 2020-11), p. 64-75
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 11 ( 2020-11), p. 64-75
    Abstract: This study investigated the feasibility of applying piezoelectric energy harvesting technology in airfield pavements through mechanistic modeling and economic analysis. The energy harvesting performance of piezoelectric transducers was evaluated based on mechanical energy induced by multi-wheel aircraft loading on flexible airfield pavements. A three-dimensional finite element model was used to estimate the stress pulse and magnitude under moving aircraft tire loading. A stack piezoelectric transducer design was used to estimate the power output of a piezoelectric harvester embedded at different locations and depths in the pavement. The aircraft load and speed were found to be vital factors affecting the power output, along with the installation depth and horizontal locations of the energy harvester. On the other hand, the installation of the energy module had a negligible influence on the horizontal tensile strains at the bottom of the asphalt layer and compressive strains on the top of the subgrade. However, the near-surface pavement strains increased when the edge ribs of the tire were loaded on the energy module. Feasibility analysis results showed that the calculated levelized cost of electricity was high in general, although it varies depending on the airport traffic levels and the service life of the energy module. With the development of piezoelectric materials and technology, further evaluation of energy harvesting applications at airports needs to be conducted.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120942503
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 6
    Online Resource
    Online Resource
    Analysis of Psychological Influences on Navigation Use While Driving Based on Extended Theory of Planned Behavior
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 9 ( 2019-09), p. 480-490
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 9 ( 2019-09), p. 480-490
    Abstract: As GPS navigation systems become more powerful, they offer the convenience of more efficient travel, and the use of such navigational aids while driving is now prevalent. Numerous issues still exist during actual use, however, such as incomprehensibility and inaccuracy of voice navigation prompts. The majority of studies have focused on humanized design and the influence on driving behavior of GPS navigation systems, while the psychological factors underlying drivers’ decisions to use them have received little attention. This study employs the extended theory of planned behavior (TPB) to investigate the psychological factors that influence drivers’ use of GPS navigation systems, including the additional variables of navigation involvement, navigation information quality, and distraction perception. Independent t-tests revealed that female, non-professional, novice, and highly educated drivers were more likely to use navigation systems. Factors analysis proved the extended TPB questionnaire to be valid and reliable. Structural equation modeling showed that attitude (0.19), subjective norms (0.14), perceived behavioral control (0.29), navigation involvement (0.36), and information quality (0.16) significantly influenced drivers’ intentions on the use of navigation. However, distraction perception (–0.05) had no significant influence. These findings demonstrate the need for navigation systems which serve drivers better. For navigation system manufacturers, the humanized design should be strengthened. For highway transportation agencies, more consistent designs for road signs are needed to improve the cooperativity between navigation and traffic signs.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119845666
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 7
    Online Resource
    Online Resource
    Study on Economic Evaluation of the Northern Sea Route: Taking the Voyage of Yong Sheng as an Example
    SAGE Publications ; 2016
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2549, No. 1 ( 2016-01), p. 78-85
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2549, No. 1 ( 2016-01), p. 78-85
    Abstract: Global warming and the retreat of the ice cover in the Arctic region have made it possible to navigate by the Northern Sea Route (NSR), a new passage in the international shipping network that will change the maritime industry. However, few commercial vessels use the NSR because of the variability in ice conditions and the uncertain economic feasibility. To evaluate the potential and feasibility of the NSR, this paper presents an account of a real voyage of the vessel Yong Sheng, which passed through the NSR in 2013. The navigation conditions, administration, and icebreaker escorting service of the route are analyzed. The voyage of the Yong Sheng is then evaluated and compared with the conventional Suez Canal Route for cost and environmental benefits. It is concluded that both the total cost and the carbon emissions of a single voyage are reduced by use of the NSR. Although the limited navigable time and uncertain conditions may undermine the advantage of the NSR, it is reasonable to consider the NSR as an alternative route to save navigation time and cost. The primary conclusion of this paper can help ship owners or operators to determine strategies for NSR service.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2549-09
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
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  • 8
    Online Resource
    Online Resource
    Automatic Identification of Vehicle Partial Occlusion in Data Collected by Roadside LiDAR Sensors
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 5 ( 2022-05), p. 708-718
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 5 ( 2022-05), p. 708-718
    Abstract: Light detection and ranging (LiDAR) sensors are receiving an increasing amount of attention in traffic detection because of their powerful capacity for providing accurate trajectory data of vehicles and non-motorized road users. When installed at the roadside, LiDAR faces the same occlusion problem as other over-roadway sensors (such as video cameras)—the integrity and reliability of object detection can be reduced when occlusion occurs. Existing occlusion reasoning methods are either developed for video sensors or require sensor fusion. Fast and accurate occlusion determination is an indispensable step in the process of vehicle detection, classification, and tracking. This paper presents a novel algorithm to automatically identify the occurrence of vehicle partial occlusion and the corresponding occluding/occluded relationship from roadside LiDAR data. According to the inherent characteristics of LiDAR sensors, two specifically designed heatmaps (ClusterID heatmap and Distance heatmap) were generated and used as the basis for fast occlusion search. Using the field data collected from two testbeds, it was shown that the proposed method could achieve about 95.60% accuracy for partial occlusion identification and a processing speed of 2 ms per frame (32-laser LiDAR sensor with 0.1 s per frame).
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211069347
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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