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  • SAGE Publications  (20)
  • Mobility and traffic research  (20)
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  • SAGE Publications  (20)
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  • Mobility and traffic research  (20)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: Recently, piezoelectric transducers have gained significant attention for energy recovery applications in road engineering. However, in laboratory tests, vehicle loads are often simplified using vertical vibration loads, thus ignoring the role of vehicle tangential loads. In this study, a power output model of a piezoelectric transducer under vertical and tangential loads was proposed through theoretical analysis. A bidirectional cyclic dynamic load test was conducted on the piezoelectric-concrete specimens in combination with a large dynamic and static straight shear instrument, and the power output law of the piezoelectric transducer under vertical and horizontal shear was investigated. The results revealed that the vertical vibration load was the main factor affecting the output performance of the piezoelectric transducer; however, with the addition of the tangential load, the electric energy output of piezoelectric pavement increased with an increase in the horizontal shear rate and displacement. When vibrating vertically (200 kPa and 4 Hz), the electric energy output of piezoelectric pavement was 4.979  μW. However, under the action of vertical vibration and horizontal shear with the working conditions of 200 kPa and 4 Hz, and 0.1 mm and 1 Hz, the electric energy output of piezoelectric pavement was 21.04  μW, which was 3.2 times that of the vertical vibration load alone. Therefore, by considering the influence of vehicle tangential loads, the power output of piezoelectric transducers can be calculated more accurately, which provides a reference for actual installed capacities in real engineering applications.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 5 ( 2023-05), p. 636-652
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 5 ( 2023-05), p. 636-652
    Abstract: Several studies have determined the positive effect of head-up display (HUD) graphic warning to support collision avoidance. However, the visual complexity of the graphic warning may overburden the driver. Design principles and empirical evidence suggest that animation and border designs may increase visual saliency and reduce the visual complexity of graphic warnings. This study aimed to examine the effects of animation (within-subject factors: animated/non-animated) and border (within-subject factors: with/without border) on drivers’ attention and driving performance. Thirty drivers (19 females) experienced five warning conditions (the no-warning condition was the baseline condition) in simulated driving conditions. The results showed the positive effects of animation and border designs on the visual detection time (animation: 25.64% reduction; border: 6.73% reduction) and attention allocation strategies (animation: 9.53% less dwell time on the warning; border: 6.62% less dwell time on the warning) when compared with the original HUD warning. We only observed a positive effect of borders on brake reaction time (17.14% reduction). However, the positive effect of the border design on brake reaction time was only observed in the non-animated warning condition, and not in the animated warning condition. A limitation of the study is that the results were generated from young and inexperienced drivers, and they should be generalized to other driver groups only with caution. Overall, we recommend using non-animated warnings with borders in conditions that require fast reactions, and animated warnings with borders in conditions that require a superior attention strategy.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 311-330
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 311-330
    Abstract: Trust calibration is essential to prevent misuse and disuse of automated vehicles (AVs). Accurate measurement and real-time identification of driver trust is an important prerequisite for achieving trust calibration. Currently, in conditionally automated driving, most researchers utilize self-reported ratings as the ground truth to evaluate driver trust and explore objective trust indicators. However, inconsistencies between the subjective rating and objective behaviors were reported, indicating that trust measurements cannot rely solely on self-reported ratings. To fill this research gap, a method of subjective and objective combination was proposed to measure and identify driver trust in AVs. Thirty-four drivers were involved in a sequence of takeover events. Monitoring ratio and subjective trusting ratings were collected, and combined to measure driver trust levels (i.e., higher and lower trust). Compared with the subjective measurement, the hybrid measurement can more reliably evaluate driver trust in AVs. More importantly, we established a real-time driver trust recognition model for AVs using label smoothing-based convolutional neural network and long short-term memory network fusing multimodal physiological signals (i.e., galvanic skin response and electrocardiogram) and interactive experiences (i.e., takeover-related lead time, takeover frequencies and system usage time). Four common models were developed to compare with the proposed model: Gaussian naive Bayes, support vector machine, convolutional neural network, and long short-term memory network. The comparison results suggest that the performance of our model outperforms others with an F1-score of 75.3% and an area under curve value of 0.812. These findings could have implications for the development of trust monitoring systems in conditionally automated driving.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 4
    Online Resource
    Online Resource
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 11 ( 2019-11), p. 604-615
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 11 ( 2019-11), p. 604-615
    Abstract: The waste of fuel causing by traffic congestion is a challenge faced by urban traffic management authorities and travelers. At the same time, massive traffic data allows high-resolution understanding of on-road operating conditions. The development of an algorithm to estimate total fuel consumption from primary traffic condition indices, for example, network average speed, will simplify the evaluation of fuel consumption from the management perspective and guide strategy at the local area level. The objective of this study is to develop a macroscopic relationship between total fuel consumption and the network average speed for an urban road network. Floating car data (FCD) covering 13 weekdays was collected in the field in Beijing, China. FCD from 10 ordinary weekdays are used to develop a quantitative model to define the macroscopic relationship between total fuel consumption and network average speed. The model is then validated by the FCD of the other three weekdays when the traffic demand is low. The average of the resultant absolute relative errors from the validation is found to be 4.65%, which indicates a reasonably high reliability of the developed model under various traffic conditions. The facility- and speed-specific distributions of vehicle kilometers traveled (VKT) are analyzed to explain the macroscopic relationship. The result indicates that the link VKT distribution at different speeds varies greatly when the traffic became congested on expressways. The link VKT distributions are similar for different traffic conditions on arterials and collectors.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 4 ( 2022-04), p. 296-307
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 4 ( 2022-04), p. 296-307
    Abstract: Large-scale activities, holidays, and emergencies often cause a significantly large burst of passenger flow demand in some urban rail transit (URT) stations in a short time, called large passenger flow (LPF). The LPF will propagate through the entire URT network of the city. The impact of the frequent occurrence of LPF on network service levels is crucial and unpredictable. This article describes an analysis of how this LPF propagates through the entire network inspired by how radionuclide imaging is done in clinical medicine. In this study, with LPF of URT as the research object, a propagation model of LPF in URT based on AFC data, train operation data, and URT network topology data was developed, which was inspired by the concept of radionuclide imaging in clinical medicine. In the condition of obtaining the list of passenger route selection ratios, the dynamic propagation state matrix of the LPF in the network is solved. The contribution value matrix of the LPF was proposed to evaluate the impact of the LPF on the URT network. Considering the LPF in Chengdu East Railway Station, China, as an example, the propagation effect of LPF in the Chengdu Metro network was analyzed, and the effectiveness of the proposed model was confirmed.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 6
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: Unlike much of the existing research into the environmental impacts of home shopping and delivery activities, which focus on evaluating the operational efficiency of home delivery failures, this paper aims to investigate the CO 2 emissions associated with treatments of failed-delivery parcels. The paper considers the potential environmental profits from using some innovative home delivery solutions: 1) the utilization of new home delivery solutions, under which the self-pickup point (SPP)/smart cabinet (SCB) is used as an intermediate address for customer’s collection and 2) upgrading fuel-powered goods vehicles to battery vans to make deliveries. Two sets of vehicle routing problem models for fuel-powered vans and battery vans are established. A sample network comprising of 500 customers and several SPPs/SCBs in Beijing, China, is proposed in the case study, to verify the proposed models and heuristics. The numerical results suggest that: 1) reductions in CO 2 per average parcel delivered by new home delivery solutions increase with the ratio of home delivery failures, 2) it is proved that using battery freight vehicles obtains more environmental benefits than using the fuel-powered vans, and 3) customers’ personal trips for collecting their failed-delivery packages from the local depot or SPPs/SCBs share a large proportion of CO 2 per parcel. The research has practical implications for both government and industry practitioners. Possible suggestions include: 1) promote a cleaner transportation mode for residents, by encouraging them to either take the bus or drive a battery passenger car, 2) careful design of a combined SPP and SCB network in urban areas, and 3) accelerate the process of vehicle electrification in the logistics industry by issuing allowances for purchasing electric vehicles from the government.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 7
    Online Resource
    Online Resource
    SAGE Publications ; 2024
    In:  Transportation Research Record: Journal of the Transportation Research Board
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: This paper develops the "formation–shield tunnel segment–reaction frame model test system." The force and failure modes of the segment under different curvature radii and different left- and right-hand thrusts are compared and analyzed. The analysis results include the following. (1) Under asymmetric thrust, the axial force, bending moment, and deformation of the segment present an asymmetric distribution. With the increase in the ratio of the thrust between the lateral and inner jacks of the turn, the loading step of the damage inside the segment lining structure is advanced. (2) With the increase in the radius of curvature, the bending moment and deformation of the segment lining decrease, but the magnitude of the sudden change in the axial force of the segment structure increases accordingly. (3) The failure locations of the segment structure are mostly concentrated at the joints between the vault and the arch. With the increase in the jack thrust ratio, the cracks caused by segment structure failure also increase, transverse crack extension occurs where the force on the outside of the turn is large, and the peeling phenomenon occurs.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2024
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  • 8
    Online Resource
    Online Resource
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 6 ( 2020-06), p. 225-243
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 6 ( 2020-06), p. 225-243
    Abstract: Rail corrugation can cause intense dynamic interaction between train and track, which can reduce riding comfort and lifespan of track structure, and even threaten running safety. Instead of investigating the root cause and growth of corrugation, this case study aims to investigate possible solutions to the excess train–track dynamic interaction excited by rail corrugation in a metro track through both numerical analysis and field experiments. Numerical analysis was performed based on a vehicle–track coupled dynamical model with field-measured rail corrugation information from two curves. The numerical analysis results indicated that rail pad stiffness was the key factor affecting wheel–rail contact force in the studied direct fixation type transit track system. Rail pads with a lower stiffness could reduce the wheel–rail interaction; however, softer rail pads will also increase the rail displacement. Therefore, both the wheel–rail contact force and rail displacement need to be considered while determining the optimal rail pad stiffness. New rail pads with a stiffness of 35 MN/m, which are softer than the original rail pads with a stiffness of 50 MN/m, were recommended for the track in this study. Through field validation and long-term monitoring, new rail pads have been proven to effectively reduce the vehicle–track dynamic interaction and ease the development of rail corrugation to a certain extent. Compared with regular rail grinding, using rail pads with the appropriate stiffness can save transit agencies a tremendous amount of time and cost. The observations from this case study can benefit transit facing rail corrugation problems.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 9
    Online Resource
    Online Resource
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 8 ( 2020-08), p. 566-580
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 8 ( 2020-08), p. 566-580
    Abstract: Micro-simulation packages provide an efficient and systematic approach to depicting traffic dynamics. Nonetheless, many of these models used by the micro-simulation packages are only calibrated with respect to observed traffic indicators such as average speed, traffic count, and so forth, while omitting non-traffic indicators. This paper aims to investigate the performance of VISSIM and TransModeler when depicting non-traffic indicators such as fuel consumption, emissions, and safety. A model was first calibrated for traffic indicators based on Next Generation SIMulation (NGSIM) trajectories. Results indicated that after calibration, simulation accuracy was still unsatisfactory with regard to energy consumption and emission measurements, with errors of up to 38.23% in VISSIM. In assessing safety, the relative error of VISSIM increased from 12.36% to 59.92% after calibration. The error in TransModeler increased to almost 100%. Furthermore, this study explored the simulation accuracy of VISSIM and TransModeler under different traffic conditions and discovered that the models’ accuracies were relatively high when simulating stop-and-go traffic. We also explored the causes of these observed differences through a regression model. This study presents practical insight into the deficiencies of micro-simulation related research, and based on error analysis, provides a theoretical reference for optimizing simulation accuracy from a novel perspective.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 10
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 3 ( 2023-03), p. 1048-1066
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 3 ( 2023-03), p. 1048-1066
    Abstract: Currently, most camera calibration methods for traffic scenes are based on vanishing points and road geometry markings with simplified camera models, which can only be applied to scenes containing straight roads. However, in practical applications, cameras are usually installed with roll angles and scenes containing curved roads, to which existing methods are not applicable. To solve the above problems, we propose a novel optimization approach for camera calibration in traffic scenes, which can be applied to curved road scenes and predict camera roll angle. Firstly, a camera space model with a camera roll angle is established for image rotation. Secondly, vehicle trajectories are extracted for the best vanishing point by a parallel coordinate system and diamond space. Vehicle trajectories are also used to obtain calibration regions for extracting road markings and edges. The road markings, edges, and the best vanishing point obtained by the above two steps automatically are more accurate and stable, especially for curved road scenes. Based on the road markings and the best vanishing point, initial calibration can be conducted. Finally, by extracting redundant markings in the calibration region, the non-linear constraint of redundant markings on the road is proposed to obtain optimized calibration parameters and predict the camera roll angle. Through experimental validation on the public dataset BrnoCompSpeed and highway scenes, the proposed approach can achieve better calibration results in both straight and curved road scenes with the mean calibration error reduced by 30% compared with the previous calibration methods.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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