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  • 1
    Online Resource
    Online Resource
    Spatiotemporal Data Warehouse for Vehicle Supervision : Grid Time–Indexed Cube Approach
    SAGE Publications ; 2013
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2399, No. 1 ( 2013-01), p. 54-62
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2399, No. 1 ( 2013-01), p. 54-62
    Abstract: The large amounts of spatiotemporal data generated by vehicle supervision systems cannot be efficiently managed by ordinary databases, mainly because of long query responses. To overcome the limitations of ordinary databases, this paper proposes a new approach, the grid time (GT)–indexed cube, which is a spatial grid–indexed, adaptive grid-based, trajectory-supported warehouse for spatiotemporal data. The GT cube partitions an embedded space–time into a set of size-fixed grids to form a cube that continues to grow throughout a constant time interval. Each grid is assigned an identifier composed of its coordinates and start time, and an aggregated value for each grid is stored in the grid records, regardless of the temporal length of the queries. Additionally, the basic grid structure of the GT cube remains unchanged at each time interval. Instead, this method refines the grid in a selected region to handle data skewing by adaptively partitioning the grid into subgrids. After extensive performance studies were conducted with spatiotemporal data from the main vehicle supervision system of Guangdong Province, China, it was observed that the GT cube achieved higher query performance than ordinary data storage technologies under various operational conditions, was easily applicable in practice, and demonstrated compatibility with traditional databases.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2399-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
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  • 2
    Online Resource
    Online Resource
    Trial Program Study of Dynamic Compaction Earth Work in Taiwan
    SAGE Publications ; 1999
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1673, No. 1 ( 1999-01), p. 39-44
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1673, No. 1 ( 1999-01), p. 39-44
    Abstract: A thermal power plant is planned to be built at Taichung Harbor area, and the construction site is located on a hydraulic fill. The medium-to-fine, loose [ N value of the Standard Penetration Test (SPT), 〈 10] sand deposits on the hydraulic fill will be subject to liquefaction, and because of this, soil improvement is required. Dynamic compaction is thus far considered one of the most appropriate methods used to solve liquefaction, and therefore, a trial program was initiated to obtain ongoing construction details for the whole construction site. The trial area was divided into three sections (Sections A, B, and C) to carry out three different trials. For Section A, the drop weight is 18 Mg, the drop height is 22 m, the grid spacing is 4 m, and the drop number is 8. For Sections B and C, the drop weights are 25 Mg, the drop heights are 25 m, grid sp acings are 5 and 6 m, respectively, and drop numbers are 10 and 40, respectively. To achieve a better result in densifying the ground surface, a post-compaction program is introduced into this project before roller compaction is performed. During the post compaction, all trials have drop weights of 13.88 Mg, drop heights of 10 m, and a grid spacing of 2 by 3 m for Section A and a grid spacing of 3 by 3 m for Sections B and C. Results of improvement are expressed as the N value of SPT (SPT- N) and cone resistance, q c . In addition, the excess pore water pressure was also investigated during compaction. Findings indicated that either the SPT- N or the Cone Penetration Test q c improved about 1.5 to 2.0 times. Satisfactory results were also detected for the post compaction. Comparison and analysis showed that the program used for the Section B trial, that is, the trial program with application of medium energy, is the most effective program for use in the whole project. In addition, the soil particle velocity caused by tamping is found to be less than 30 mm/s and will cause no tangible effect on adjacent structures.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1673-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1999
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  • 3
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    Online Resource
    Global System for Transportation Simulation and Visualization in Emergency Evacuation Scenarios
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2529, No. 1 ( 2015-01), p. 46-55
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2529, No. 1 ( 2015-01), p. 46-55
    Abstract: Simulation-based studies are frequently used for evacuation planning and decision making. Given the complexity of and data availability for transportation systems, most evacuation simulation models focus on certain geographic areas. With routine improvement of OpenStreetMap road networks and LandScan global population distribution data, this paper presents the Toolbox for Urban Mobility Simulations (TUMS). TUMS uses unified data structure for simulation inputs. The toolbox also integrates a supernode trip distribution model as the default simulation parameter to improve the system computational performance. Two levels of visualization tools, including link-based macroscopic visualization and vehicle-based microscopic visualization, are implemented for evacuation performance analysis. For left-hand and right-hand traffic patterns in different countries, the authors propose a mirror technique to experiment with both scenarios without significantly changing traffic simulation models. Sixteen cities in the United States, Europe, the Middle East, Asia, and Africa are modeled for demonstration. With default traffic simulation models for fast and easy-to-use evacuation estimation and visualization, TUMS also retains the capability of interactive operation for users to adopt customized traffic simulation models. For the first time, TUMS provides a unified platform with which global evacuation researchers can estimate and visualize the performance of transportation systems under evacuation scenarios.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2529-05
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
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  • 4
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    Online Resource
    Nonlinear Model-Based Subway Station-Level Peak-Hour Ridership Estimation Approach in the Context of Peak Deviation
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 6 ( 2022-06), p. 549-564
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 6 ( 2022-06), p. 549-564
    Abstract: Existing techniques for estimation of subway station-level long-term peak-hour ridership (PHR) may produce underestimated PHR values that may result in stations being designed with insufficient capacity during the planning stage; this in turn may increase congestion on the platforms in actual operation. One of the reasons for this potential undesirable outcome is that peak deviation phenomena often arise between stations and lines in subway systems, which could create underestimated PHR values. The default assumption has always been that the peak hour of passenger flow of each station always overlaps with its attributed line. This paper presents a framework of a station-level long-term PHR estimation method calibrated using the peak deviation coefficient (PDC) and a nonlinear model (eXtreme Gradient Boosting). This approach can estimate the PDC values for PHR prediction, and can also quantify the relative importance of PDC associated factors, yielding an explanation of the main causes of peak deviation phenomena. Using a real-world, large-scale passenger flow dataset from Xi’an, China, the approach produces more stable and accurate predictive performance compared with conventional methods (i.e., absolute percentage error controlled within 20% versus 50%, and mean average percentage error reduced by 3.26%–8.35%). Meanwhile, it is found that the relative importance of the unimproved land use ratio ranks in the top four for all types of peak periods; this ratio is a key factor that may be used to mitigate ridership deviations between stations and line peaks. In addition, for subway networks, the influence of land use entropy increases from the morning peak hour to the evening peak hour and weakens across the route from origin to destination.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221075624
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 5
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    Online Resource
    Capacity and Other Traffic Characteristics in Taiwan's 12.9-km-Long Shea-San Tunnel
    SAGE Publications ; 2009
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2130, No. 1 ( 2009-01), p. 101-108
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2130, No. 1 ( 2009-01), p. 101-108
    Abstract: The 12.9-km-long Shea-San Tunnel, located on Taiwan's 54-km-long National Highway 5 (NH-5), has two one-way tubes. To minimize accidents and to respond to the need for improved operating efficiency on NH-5, Taiwan's Bureau of National Highways adopts a graduated approach in traffic control. Before October 2007, the bureau set a uniform speed limit of 70 kilometers per hour (km/h) for NH-5 and allowed only passenger cars and other small vehicles to enter the Shea-San Tunnel and the adjacent Pern-San Tunnel. With the exception of the Shea-San Tunnel, the speed limit was raised to 80 km/h in October 2007. In November 2007, the bureau opened all the tunnels to commercial buses and, most recently, the bureau raised the speed limit in the Shea-San Tunnel to 80 km/h. One traffic regulation that remains unchanged is that motorists in the Shea-San Tunnel must maintain a minimum car-following distance of 50 m under normal conditions. The capacities of the two tubes in the Shea-San Tunnel are still low. This study uses detector data to examine the spatial and temporal variations of capacity, free-flow speed, passenger car equivalents of buses, and speed–flow relationship.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2130-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2009
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  • 6
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    Online Resource
    Comparison of Methods for Allocating Costs of Empty Railcar Movements in a Railcar Pooling System
    SAGE Publications ; 2005
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1916, No. 1 ( 2005-01), p. 88-95
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1916, No. 1 ( 2005-01), p. 88-95
    Abstract: Allocating the cost of empty railcar miles to partners in a railcar pooling system is an important pricing problem in railway management. Recently, the authors of this paper proposed a cost allocation scheme for empty railcar movements based on game theory that explicitly considers the level of participation and contribution from each partner, the costs generated before and after cooperation, and the overall benefit obtained by each partner because of cooperation. This paper compares the performance of the model with three other cost allocation models with respect to fairness, stability, and computational efficiency. The comparison is made with two scenarios adapted from examples documented in the literature. The results indicate that the cost allocation scheme based on game theory outperforms other methods in ensuring fairness and enhancing stability in a coalition. Most remarkably, it yields reasonable results even in situations in which other models behave poorly. Computationally, it is manageable for practical problems.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198105191600112
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2005
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  • 7
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    Online Resource
    Vehicle Classification Using Advanced Technologies
    SAGE Publications ; 1996
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1551, No. 1 ( 1996-01), p. 45-50
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1551, No. 1 ( 1996-01), p. 45-50
    Abstract: Applying advanced technologies to existing problem domains is a highly desirable approach in many research areas. Among these techniques, image processing has been shown useful in transportation fields for such tasks as traffic pattern recognition, data collection, accident detection, and pavement evaluation. The integrated model with artificial neural networks (ANNs) has promising potential applications. The image processing and ANN model are combined to explore the feasibility of vehicle classification in real-world situations. Three methods were developed during the research process: ground segmentation, background subtraction, and window segmentation. The first two methods were used to separate the objects of scene and nonscene from the actual traffic image. To reduce the complexity of neural networks, the image was divided into 16 windows and three characteristics (occupation rates of vehicles, of horizontal image lines, and of vertical image lines) of each window were extracted to generate 48 factors as the input units of the neural network. The backpropagation ANN model with one hidden layer is employed. The experiments show that the accurate recognition rates of heavy vehicles, small cars, and motorcycles are 98.5, 96.92, and 91.94 percent, respectively. The result implies the remarkable applicability of the proposed methods in transportation areas.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198196155100106
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1996
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  • 8
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    Online Resource
    Alternative Quasi-Newton Methods for Capacitated User Equilibrium Assignment
    SAGE Publications ; 2003
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1857, No. 1 ( 2003-01), p. 109-116
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1857, No. 1 ( 2003-01), p. 109-116
    Abstract: Two quasi-Newton methods are proposed to deal with traffic assignment in a capacitated network. The methods combine Newton formula, column generation, and penalty techniques. The first method uses the gradient of the objective function to obtain an improving feasible direction scaled by the second-order derivatives. The second one uses a Rosen gradient to obtain an improving direction scaled by the corresponding origin–destination demand. Both methods make a line search to obtain an optimal step size to guarantee the feasibility of either path or link flow. The proposed methods are of fast convergence and high accuracy at the expense of saving path information. Numerical examples verify their efficiency and stability. The quasi-Newton method with a straight gradient demonstrates more stability than the Rosen gradient for capacitated traffic assignment.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1857-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2003
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  • 9
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    Online Resource
    Catchment-Area Delineation Approach Considering Travel Purposes for Station-Level Ridership Prediction Task
    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: Station-catchment-area delineation is a key component of direct ridership models for urban rail-transport systems as it can determine the relationship between the urban-rail-transit station-level ridership and the variables within the station catchment area. The neglect of differences in the passenger-flow distribution for different travel purposes in previous studies has led to low accuracy of the obtained walk-to-station distances. Therefore, this paper proposes a station-catchment-area delineation method which is based on web map data to obtain accurate walk-to-station distances and considers differences in the distance thresholds and the ridership attraction intensity (RAI) for six travel purposes (corresponding to commercial, medical, residential, educational, administrative, and recreational land uses). In the case study, the ridership data of Xi’an Metro, the 2015 Xi’an Residential Travel Survey data, and the corresponding Gaode Map data are employed to extract passengers’ walking-distance distribution for several travel purposes to delineate the station catchment areas and build direct ridership models. Several geographically weighted regression (GWR) models are constructed to evaluate and examine the effects of the various station-catchment-area delineation methods on the model findings. The obtained results show that the proposed station-catchment-area delineation method significantly improves the ridership prediction performance compared with the traditional circular-buffer method, with the entry and exit ridership prediction accuracy improving by 3.57% and 6.65% on average, respectively. Finally, this study will guide transportation planners on how to delineate station catchment areas when constructing direct-demand models for urban rail stations.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231189738
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 10
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    Online Resource
    Engineering Properties of Recycled Plastic Pins for Slope Stabilization
    SAGE Publications ; 2003
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1849, No. 1 ( 2003-01), p. 39-46
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1849, No. 1 ( 2003-01), p. 39-46
    Abstract: An ongoing demonstration project has shown the feasibility of using slender (90 mm × 90 mm × 2.4 m) recycled plastic pins (RPPs) for in situ reinforcement of slopes and embankments. The technique uses RPPs driven into the face of the slope in a grid pattern to intercept the sliding surface and “pin” the slope. The engineering properties of the RPPs, including the compressive, tensile, and flexural strength along with creep behavior, dictate the design and construction practice. Constituent materials and manufacturing processes are highly variable among the more than 30 U.S. manufacturers. A specification for acceptance of the members is needed; however, before an effective specification can be developed, the appropriate engineering properties and design requirements for the RPPs must be determined. The engineering properties and driving performance of four different types of members were evaluated and are reported on. Additional evaluations are under way.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1849-05
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2003
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