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  • Mobility and traffic research  (24)
  • 1
    Online Resource
    Online Resource
    Deep Learning-Based Lane Marking Detection using A 2 -LMDet
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 11 ( 2020-11), p. 625-635
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 11 ( 2020-11), p. 625-635
    Abstract: Automated lane marking detection is essential for advanced driver assistance system (ADAS) and pavement management work. However, prior research has mostly detected lane marking segments from a front-view image, which easily suffers from occlusion or noise disturbance. In this paper, we aim at accurate and robust lane marking detection from a top-view perspective, and propose a deep learning-based detector with adaptive anchor scheme, referred to as A 2 -LMDet. On the one hand, it is an end-to-end framework that fuses feature extraction and object detection into a single deep convolutional neural network. On the other hand, the adaptive anchor scheme is designed by formulating a bilinear interpolation algorithm, and is used to guide specific-anchor box generation and informative feature extraction. To validate the proposed method, a newly built lane marking dataset contained 24,000 high-resolution laser imaging data is further developed for case study. Quantitative and qualitative results demonstrate that A 2 -LMDet achieves highly accurate performance with 0.9927 precision, 0.9612 recall, and a 0.9767 [Formula: see text] score, which outperforms other advanced methods by a considerable margin. Moreover, ablation analysis illustrates the effectiveness of the adaptive anchor scheme for enhancing feature representation and performance improvement. We expect our work will help the development of related research.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120948508
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 2
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    Fuzzy Programming Approach for the Electric Multiple Unit Circulation Planning Problem Using Simulated Annealing
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 7 ( 2022-07), p. 456-467
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 7 ( 2022-07), p. 456-467
    Abstract: Circulation planning for electric multiple units (EMUs) is regarded as one of the key operation issues for a high-speed railway transportation system. The EMU circulation plan consists of determining the connections of trains while accomplishing the passengers’ demands. EMUs need regular maintenance at a certain interval of kilometers or minutes for safety reasons. Consequently, the circulation plan must ensure that EMU trains can reach the maintenance depots in time for their required maintenance. This paper proposes a 0-1 integer programming model for the EMU circulation plan with the aim of minimizing the total costs of the mileage losses of the EMUs, which is incurred when they undergo a maintenance check before the corresponding travel mileage reaches the limit of the cycle. Given that the accumulated travel mileage of EMUs is allowed to be 10% above the standard mileage cycle in practice, an ingenious fuzzy maintenance constraint is presented to tackle the mileage cycle constraint with a certain elasticity. The exterior penalty function is employed to deal with the fuzzy constraint and a simulated annealing (SA) heuristic is employed to solve the model. The modeling and solving approach are applied to a practical instance in the context of China’s high-speed railway system. Compared with the average travel mileage of EMU trains using the manual solution, with the SA solution an increase of 293 km was observed. It can be then concluded that the optimization method presented in this paper can effectively improve the quality of the EMU circulation plan.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221078848
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 3
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    Aberrant Driving Behavior Prediction for Urban Bus Drivers in Taiwan Using Heart Rate Variability and Various Machine Learning Approaches: A Pilot Study
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 3 ( 2023-03), p. 1304-1320
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 3 ( 2023-03), p. 1304-1320
    Abstract: Objective: Aberrant driving behavior (ADB) decreases road safety and is particularly relevant for urban bus drivers, who are required to drive daily shifts of considerable duration. Although numerous frameworks based on human physiological features have been applied to predict ADB, the research remains at an early stage. This study used heart rate variability (HRV) parameters to establish ADB occurrence prediction models with various machine learning approaches. Methods: Twelve Taiwanese urban bus drivers were recruited for four consecutive days of naturalistic driving data collection (from their routine routes) between March and April 2020; driving behaviors and physiological signals were obtained from provided devices. Weather and traffic congestion information was determined from public data, while sleep quality and professional driving experience were self-reported. To develop the ADB prediction model, several machine learning models—logistic regression, random forest, naive Bayes, support vector machine, and gated recurrent unit (GRU)—were trained and 10-fold cross-validated by using the testing data. Results: Most drivers with ADB reported deficient sleep quality (≤80%), with significantly higher mean scores on the Karolinska Sleepiness Scale and driver behavior questionnaire subcategory of lapses and errors than drivers without ADB. Next, HRV indices significantly differed between the measurement of a pre-ADB event and a baseline. The accuracy of the GRU models ranged from 78.84% ± 1.49% to 89.57% ± 1.31%. Conclusion: Drivers with ADB tend to have inadequate sleep quality, which may increase their fatigue levels and impair driving performance. The established time-series models can be considered for ADB occurrence prediction among urban bus drivers.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221123802
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 4
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    Characterizing Influence of Water Access Condition during Freezing on Resilient Behavior of Alaskan Base Course Materials
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 6 ( 2020-06), p. 151-162
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 6 ( 2020-06), p. 151-162
    Abstract: Accurate characterization of the resilient behavior of the base course materials under different climatic conditions is critical for the design of reliable and cost-effective pavement structures. In Alaska, the resilient behavior of base course materials usually undergoes significant variation due to seasonal change and extreme climatic conditions. Previous studies have revealed that the resilient behavior of base course materials could be significantly influenced by the freezing process. In this study, the freezing process under two extreme conditions (i.e., free and no water access conditions) that base course materials could possibly experience in the field was simulated using a one-dimensional frost heave cell. The influences of the water access condition during freezing on the frost heave and resilient modulus (M R ) of the base course materials with different fines and initial water contents was assessed based on the results from the freezing process and repeated load triaxial tests. A pressure plate test was also performed to build the relationship between suction and water content of soils with different fines content. Suction was then introduced to model M R of the materials tested under unfrozen conditions before and after a freeze–thaw cycle. The adoption of suction significantly simplified the equation for M R prediction. Finally, structural analyses were conducted using BISAR and Alaska Flexible Pavement Design (AKFPD) software and the results revealed that free water access during freezing can significantly accelerate cracking and reduce pavement service life.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120918242
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 5
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    Effect of Microbial-Induced Calcite Precipitation on Surface Erosion and Scour of Granular Soils : Proof of Concept
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2657, No. 1 ( 2017-01), p. 10-18
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2657, No. 1 ( 2017-01), p. 10-18
    Abstract: Erosion is relevant to a variety of infrastructure problems such as bridge scour, roadway shoulder erosion, coastal erosion, and riverbank and slope stability. This research investigated the feasibility of using microbial-induced calcite precipitation (MICP) as an erosion countermeasure. MICP is a natural phenomenon in which calcite precipitation occurs as a consequence of microbial metabolic activity. The precipitated calcite modifies the soil fabric and provides an additional bonding force between soil particles. In this paper, a preliminary experimental study on the erosional behavior of MICP-treated sand is presented. A standard soil, Ottawa graded sand, was treated with a bacterium (Sporosarcina pasteurii) in a full-contact reactor-one in which the soil in a fabric mold was fully immersed in the bacteria and cementation solution. The morphologies and crystalline structures of the precipitated calcite in porous sediments were characterized using microscopic imaging techniques. The treated soil samples were tested in a flume to investigate the erosional behavior; both surface erosion and bridge scour tests were conducted. Although the untreated soil is highly erodible, the erosion of the treated sand was found to be negligible under the circumstances of the test; however, some concerns were raised regarding practical applications. Efforts will be made in the future to identify alternative treatment procedures that are more applicable to the field.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2657-02
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 6
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    Surface Drainage Evaluation for Rigid Pavements Using an Inertial Measurement Unit and 1-mm Three-Dimensional Texture Data
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2457, No. 1 ( 2014-01), p. 121-128
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2457, No. 1 ( 2014-01), p. 121-128
    Abstract: During high-intensity rainfall, hydroplaning is likely and can affect driving safety. Studies have indicated that the risk of hydroplaning increases with the increase in the water film depth that is dependent on surface texture properties, flow path slope, flow path length, rainfall intensity, and pavement surface type. However, little research work has been conducted to investigate pavement surface drainage at network levels because the existing data acquisition systems cannot continuously measure related data sets at high speeds. In the presented study, texture data were continuously collected at high speeds with the emerging 1-mm three-dimensional (3-D) PaveVision3D Ultra technology. The cross slope and longitudinal grade data were acquired with an inertial measurement unit system. Data from two rigid pavements constructed with dragged and grooved surface texture were used in this study. The analysis of variance test and the multifactor treatment statistical method were used to investigate the factors that influence the calculation of water film depth. Texture properties and flow path slope were determined to be more significant for surface drainage capacity than was flow path length. The widely used PAVDRN model was used to calculate hydroplaning speed, and the potential hydroplaning performance of the test sites was evaluated. The significance of the presented data is twofold. First, it integrates the real-time 1-mm 3-D surface data and inertial measurement unit system data into a hydroplaning speed prediction model. Second, this method can identify hazardous locations where there is hydroplaning so that pavement engineers may take remedial measures, such as constructing superior grooving texture or posting appropriate traffic speed signs, to decrease hydroplaning potential and minimize traffic accidents.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2457-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 7
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    Novel Cooperative Collision Avoidance Model for Connected Vehicles
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2645, No. 1 ( 2017-01), p. 144-156
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2645, No. 1 ( 2017-01), p. 144-156
    Abstract: Connected vehicle technology exchanges real-time vehicle and traffic information through vehicle-to-vehicle and vehicle-to-infrastructure communication. The technology has the potential to improve traffic safety applications such as collision avoidance. In this paper, a novel cooperative collision avoidance (CCA) model that could improve the effectiveness of the collision avoidance system of connected vehicles was developed. Unlike traditional collision avoidance models, which relied mainly on emergency braking, the proposed CCA approach avoided collision through a combination of following vehicle deceleration and leading vehicle acceleration. Through spacing policy theory and nonlinear optimization, the model calculated the desired deceleration rate for the following vehicle and the acceleration rate for the leading vehicle, respectively, at each time interval. The CCA approach was then tested on a scaled platform with hardware-in-the-loop simulation embedded with MATLAB/Simulink and a car simulator package, CarSim. Results show that the proposed model can effectively avoid rear-end collisions in a three-vehicle platoon.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2645-16
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 8
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    Laboratory Study on Entire Range Suction Measurement and Microstructure Change of Granite Residual Soil
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 10 ( 2023-10), p. 191-203
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 10 ( 2023-10), p. 191-203
    Abstract: The shear strength of unsaturated granite residual soil (GRS) will decline rapidly when moisture content increases, because of loss of matric suction in the soil. This can lead to slope instability and embankment collapse during rainfall. Determining the matric suction of GRS accurately at different conditions can improve the accuracy of stability analysis. Generally, matric suction can be characterized as the soil–water characteristic curve (SWCC), and it is closely related to soil microstructure. In this study, the entire range of matric suction was measured using a combination of pressure plate method, filter paper method, and vapor equilibrium method. Microstructure change was investigated based on mercury intrusion porosimeter tests, in which the pore size distribution (PSD) curves of GRS samples with different initial densities and moisture content were measured. The PSDs of samples before and after wetting were also measured and compared to investigate the influence of water intrusion. Test results indicate that the combination of measurement methods can cover the entire matric suction range. The microstructure of GRS with different initial conditions presents a clear bimodal PSD. At the same density, the increase in initial moisture content can increase intra-aggregate pores and decrease inter-aggregate pores. When initial density increases, only the volume of inter-aggregate pores decreases. Wetting can decrease inter-aggregate pores and increase intra-aggregate pores. Finally, the Li model is applied in SWCC fitting for tested samples, the result of which performs well with a high correlation coefficient (R 2 〉 0.95) and is recommended for GRS analysis.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231160546
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 9
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    A Numerical Study on Installation Effects and Long-Term Shaft Resistance of Pre-Bored Piles in Cohesive Soils
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 3 ( 2019-03), p. 494-505
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 3 ( 2019-03), p. 494-505
    Abstract: Pre-boring is a technique widely used to facilitate large displacement pile driving in hard/dense soils, but usually at the expense of reducing the long-term shaft resistance of the pile. In the US, it is a routine practice for large displacement pile to be driven through dense cohesive soils with the ultimate capacity of pre-bored piles usually being determined based on empiricism and local experience. Understanding and quantifying the impacts of pre-boring installation on pile capacity can greatly help geotechnical design engineers to understand the interactions among the factors of pre-boring, pile size, soil conditions, and so forth and to improve the design and construction qualities of pile foundations in hard/dense soils. Due to the high cost and time involved with field instrumentation and testing on pre-bored piles, a numerical analysis study was funded by the Louisiana Department of Transportation and Development (DOTD) as a first step to exploring the impacts of pre-bore size on the long-term shaft resistance reduction of piles. This study was conducted using a practical finite element model that integrates the entire process from pile installation through subsequent consolidation to pile loading. The long-term shaft resistance was then examined after full consolidation by applying a vertical shear displacement on the soil element adjacent to the pile until the ultimate state was reached. Based on the numerical simulations, a set of reduction factor curves were then developed for a typical Louisiana soil stratum, which may provide guidelines for better design and construction of pre-bored piles in Louisiana.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119835505
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 10
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    Modified Unconfined Compression Testing System to Characterize Stress–Strain Behavior of Unsaturated Soils at Low Confining Stresses
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2510, No. 1 ( 2015-01), p. 54-64
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2510, No. 1 ( 2015-01), p. 54-64
    Abstract: In geotechnical and pavement engineering, many projects involve shallow, unsaturated soil with low confining stress. Suction-controlled triaxial tests usually are used to investigate stress–strain behavior (i.e., deformation and strength) in such soils. However, because they require significant modifications to the conventional apparatus used to test saturated soils and are time-consuming to perform, the tests cannot be justified for time-sensitive engineering projects. A modified unconfined compression testing system is presented to investigate the stress–strain behavior of unsaturated soils at low confining stresses. Negative air pressure (i.e., vacuum) provides the low confining pressure required for the tests, and high-suction tensiometers are used to monitor variations in the soil matric suction during testing. A photogrammetric method is used to reconstruct the three-dimensional model of unsaturated soil specimens, from which total and localized volume changes are calculated. Methods are proposed for unsaturated shear strength analysis. A series of tests was carried out to demonstrate the use of the modified unconfined compression testing system to evaluate the stress-strain behavior of unsaturated soil under different confining stresses. Results indicated that the newly developed modified unconfined compression testing system was a cost-effective method for the rapid evaluation of stress–strain behavior of unsaturated soils under low confining stresses.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2510-07
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
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