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  • Mobility and traffic research  (23)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2005
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1935, No. 1 ( 2005-01), p. 85-92
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1935, No. 1 ( 2005-01), p. 85-92
    Abstract: A key feature in estimating and applying destination choice models with aggregate alternatives is to sample a set of nonchosen traffic analysis zones (TAZs), plus the one a trip maker chose, to construct a destination choice set. Computational complexity is reduced because the choice set would be too large if all study area TAZs were included in the calibration. Commonly, two types of sampling strategies are applied to draw subsets of alternatives from the universal choice set. The first, and simplest, approach is to select randomly a subset of nonchosen alternatives with uniform selection probabilities and then add the chosen alternative if it is not otherwise included. The approach, however, is not an efficient sampling scheme because most alternatives for a given trip maker may have small choice probabilities. The second approach, stratified importance sampling, draws samples with unequal selection probabilities determined on the basis of preliminary estimates of choice probabilities for every alternative in the universal choice set. The stratified sampling method assigns different selection probabilities to alternatives in different strata. Simple random sampling is applied to draw alternatives in each stratum. However, it is unclear how to divide the study area so that destination TAZs may be sampled effectively. The process of and findings from implementing a stratified sampling strategy in selecting alternative TAZs for calibrating aggregate destination choice models in a geographic information system (GIS) environment are described. In this stratified sampling analysis, stratum regions varied by spatial location and employment size in the adjacent area were defined for each study area TAZ. The sampling strategy is more effective than simple random sampling in regard to maximum log likelihood and goodness-of-fit values.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2005
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2193, No. 1 ( 2010-01), p. 116-123
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2193, No. 1 ( 2010-01), p. 116-123
    Abstract: A short-term, real-time system was developed to support traffic management in Beijing. The requirements of a large amount of data and unstable traffic flow are the biggest challenges to such a system. The models and software framework thus should be effective enough to face these problems. The core of such a system is the short-term traffic flow forecast model. Rapid urbanization and transportation development in Beijing have led to traffic flow patterns with some unstable characteristics. The short-term forecast model for an online system thus was designed with the fast-paced trend in mind. The model considers historical data, real-time data, and space data, and it can be updated online. Thus a combined model was developed with three submodels: discrete Fourier transform model, autoregressive model, and neighborhood regression model. Weights of each submodel were based on forecast error. Both the historical forecast error and real-time forecast error were considered. The system was built on a browser–server structure to support combined forecast models. The framework, modules, and interface of this system are introduced in this paper.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2006
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1971, No. 1 ( 2006-01), p. 59-65
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1971, No. 1 ( 2006-01), p. 59-65
    Abstract: Dwell time at a bus stop is one of the major components of bus travel time, and it is highly correlated with numbers of boarding and alighting passengers. With more resources from federal, state, and local governments currently being devoted to improving public transit services, transit ridership rates are expected to increase. Consequently, dwell time needs to be modeled in terms of ridership to allow accurate estimations of bus travel time. Typically, passengers can board a bus only through the front door but can choose to exit the vehicle through either the front or rear door. To estimate dwell time accurately, this study used data collected from Florida's Broward County Transit system to develop a binary door choice model predicting the proportion of alighting passengers who will use the front or rear door to disembark from the bus. Because the model explicitly considered passengers disembarking through the front and rear doors as well as passengers boarding through the front door, it was more effective in quantifying transit dwell time than the existing simulation algorithms available in CORSIM and VISSIM.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
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  • 4
    Online Resource
    Online Resource
    SAGE Publications ; 2005
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1931, No. 1 ( 2005-01), p. 18-27
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1931, No. 1 ( 2005-01), p. 18-27
    Abstract: Discrete choice modeling techniques have been used to model simultaneously the effects of land use and socioeconomic and demographic characteristics on travel behavior. To evaluate the performance of destination choice models with aggregate alternatives at the level of the travel analysis zone in allocating trips between zone pairs, this study developed three sets of home-based work models by using data collected from Broward, Palm Beach, and Volusia Counties in Florida. An objective for this study was to identify the benefit of destination choice models to urban areas of different sizes and characteristics. The spatial distribution patterns from the models were compared with those obtained from gravity models. The results from this study show that all urban areas benefited from destination choice models regardless of the urban size.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2005
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  • 5
    Online Resource
    Online Resource
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2623, No. 1 ( 2017-01), p. 49-59
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2623, No. 1 ( 2017-01), p. 49-59
    Abstract: Queue length is one of the most important performance measures for signalized intersections. Many methods for queue length estimation based on various data sources have been proposed in the literature. With the latest developments and applications of probe vehicle systems, cycle-by-cycle queue length estimation based only on probe data has become a promising research topic. However, most existing methods assume that information such as signal timing, arrival pattern, and penetration rate is known, an assumption that constrains their applicability in practice. The objective of this study was to propose a cycle-by-cycle queue length estimation method using only probe data without the foregoing assumption. Based on the shock wave theory, the proposed method is capable of reproducing the dynamic queue forming and dissipating process cycles at signalized intersections by using probe vehicle trajectories. To reproduce the queuing processes, the inflection points of probe vehicle trajectories representing the changes of arrival patterns are identified and extracted from the trajectory points of vehicles joining and leaving the queue. A piecewise linear function is then used to fit all the inflection points to estimate the stopping and discharging shock waves. Finally, signal timing data and queue lengths can be calculated on the basis of the estimated shock waves. Under both saturated and oversaturated traffic conditions, the performance of the method is comprehensively evaluated through 60 simulation scenarios, which cover sampling intervals from 5 s to 60 s and penetration rates ranging from 5% to 100%. Results show that compared with the method proposed by Ramezani and Geroliminis in 2015, the proposed method has more robustness for all the sampling intervals and displays more estimation accuracy of queue length and a higher success rate under conditions of low penetration rate.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 6
    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
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  • 7
    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: Electric mobility transition has been gradually gaining momentum, driven by several considerations, including the urgency to combat climate change impacts attributed to private transport based on the internal combustion engine. The nature and impacts of such a transition will inevitably vary across countries because of differences in the mobility patterns and preferences in the societies, as well as the policy landscape. In Sub-Saharan Africa, paratransit is one of the dominant forms of transport. This motivates the need to assess its viability for electric mobility transition, focusing on electric motorcycles in particular. Using Kenya as case study, in conjunction with mobility data collected in several Sub-Saharan countries, this research provides insight on the potential adoption and impacts of electric motorcycles in the taxi industry, based on the observed trip characteristics and relative fuel and electricity costs. The economic benefits for taxi drivers as well as the capability of the electricity infrastructure to support such transition are considered. The paper concludes that the transition to electric mobility among motorcycle taxis is feasible in Kenya. The paper also discusses implications for the electricity grid, in relation to the possible increase in the electricity consumption and power needs under various electric two-wheeler proliferation scenarios.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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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. 1 ( 2020-01), p. 319-329
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 1 ( 2020-01), p. 319-329
    Abstract: This paper intends to analyze the Light Detection and Ranging (Lidar) sensor performance on detecting pedestrians under different weather conditions. Lidar sensor is the key sensor in autonomous vehicles, which can provide high-resolution object information. Thus, it is important to analyze the performance of Lidar. This paper involves an autonomous bus operating several pedestrian detection tests in a parking lot at the University at Buffalo. By comparing the pedestrian detection results on rainy days with the results on sunny days, the evidence shows that the rain can cause unstable performance and even failures of Lidar sensors to detect pedestrians in time. After analyzing the test data, three logit models are built to estimate the probability of Lidar detection failure. The rainy weather still plays an important role in affecting Lidar detection performance. Moreover, the distance between a vehicle and a pedestrian, as well as the autonomous vehicle velocity, are also important. This paper can provide a way to improve the Lidar detection performance in autonomous vehicles.
    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 ; 2021
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2675, No. 12 ( 2021-12), p. 1422-1431
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2675, No. 12 ( 2021-12), p. 1422-1431
    Abstract: To achieve a green and sustainable public transit system, most transit agencies plan to completely replace current diesel and hybrid buses with battery-powered electric buses (EBs) in the decades ahead. Based on performances of EBs in practical operations, this study develops a transit fleet replacement model using multi-type EBs to determine an optimal fleet replacement plan in a cost-effective manner, considering associated diesel–electric replacement rates and in-vehicle crowd costs for passengers. Multi-type EBs include small EBs with fast charging technique, and large EBs with fast and slow charging techniques. The proposed model is applied to a real-life case study of the transit system in Qingdao, China. The results obtained indicate that large EBs with a high price tag are preferentially purchased in the first few years of the analysis period, whereas small EBs with a low price tag are favored in the latter years. The use of multi-type EBs results in a significant saving of the total cost, compared with the use of single-type EBs. Interestingly, with the increase of passenger demand, a large EB with a fast charging method presents more benefits than others. In contrast, a small EB has more advantages in a transit system with low demand.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2403378-9
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  • 10
    Online Resource
    Online Resource
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2483, No. 1 ( 2015-01), p. 1-9
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2483, No. 1 ( 2015-01), p. 1-9
    Abstract: The capacity of signalized intersections with a permissive left-turn phase is influenced significantly by the gap acceptance of left-turners. Left-turners' perception of risk when they are deciding whether to accept a gap is of great importance for understanding such driver behavior and for developing countermeasures to improve intersections. This study's objective was thus to model the tradeoff relationship between the perceived risk and the time-saving benefit in gap acceptance for left-turners in China. In the proposed model, the perceived risk was measured by the postencroachment time of the left-turning vehicle and of the gap-ending through vehicle at the conflict; the time-saving benefit was indicated by the potential time to wait for the next acceptable gap. A gap acceptance model that incorporated both variables was then developed and validated by using data collected at two intersections in Shanghai. The acceptable risk level of left-turners could then be defined as the ratio of the estimated model coefficients of those two variables. Results indicated that the wait time significantly affected the gap acceptance and the critical gap decreased as the acceptable risk level rose. In addition, the acceptable risk level was found to be approximately 60 at the observed intersections. With the results, impacts of the acceptable risk level on the capacity of permissive left-turn traffic were investigated through a numerical study. The findings revealed that the capacity of permissive left-turn traffic could be stochastic in nature rather than constant because of random traffic flow characteristics as well as different risk perceptions of drivers.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
    detail.hit.zdb_id: 2403378-9
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