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  • Mobility and traffic research  (14)
  • 1
    Online Resource
    Online Resource
    Innovative Operating Strategies for Paratransit Services with Zoning
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2469, No. 1 ( 2014-01), p. 120-128
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2469, No. 1 ( 2014-01), p. 120-128
    Abstract: Paratransit services constitute a large industry that provides transportation services to disabled and elderly customers across the country. Demand for these services has been growing since the Americans with Disabilities Act (ADA) was signed into law in 1990 and will continue to grow in the foreseeable future. Rather than adopt a centralized operating strategy, some large transit agencies use decentralized zoning for easier management and better overall reliability (i.e., higher percentage of on-time performance). However, this strategy is inefficient, because a service provider's vehicle is not allowed to pick up customers outside its own service zone. This ban hampers ridesharing and increases the empty trip miles driven. To address this issue, the study reported in this paper explored innovative ADA operating strategies that allowed service providers to serve both trips of cross-zonal customers in need of round trip rides. Three innovative policies were proposed. New algorithms were developed to incorporate the proposed strategies into the insertions heuristically. Simulation experiments on the basis of data in Houston, Texas, and Los Angeles, California, were conducted to quantify the performance improvement over current policy. Results showed that, without sacrifices to customer levels of service, the best of the three policies analyzed could significantly reduce the inefficient empty trip miles by up to 25%. As a result, the policy could save up to 6.8% in assigned vehicles and lower the total mileage by 8%; these results implied a significant savings in operating costs with a reasonable level of service quality maintained.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2469-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 2
    Online Resource
    Online Resource
    Empirical Mode Decomposition–Autoregressive Integrated Moving Average : Hybrid Short-Term Traffic Speed Prediction Model
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2460, No. 1 ( 2014-01), p. 66-76
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2460, No. 1 ( 2014-01), p. 66-76
    Abstract: Short-term freeway traffic speed prediction is essential to improving mobility and roadway safety. It has been a challenging and unresolved issue. Traffic speed prediction can be applied to enhance the intelligent freeway traffic management and control for applications such as operational and regulation planning. For example, with more reliable traffic speed prediction, the advanced traveler information system can provide travelers with predictive travel time information and optimal routing, which allows them to arrange their schedules accordingly. Moreover, traffic managers can use the predicted information to deploy various traffic management strategies to increase system efficiency. In this paper, a hybrid empirical mode decomposition (EMD) and autoregressive integrated moving average (ARIMA) (or EMD-ARIMA) approach was developed to predict the short-term traffic speed on freeways. In general, there were three stages in the hybrid EMD-ARIMA forecasting framework. The first was the EMD stage, which decomposed the freeway traffic speed time series data into a number of intrinsic mode function (IMF) components and a residue. The second stage was to find the appropriate ARIMA model for each IMF and residue and then make predictions on the basis of the appropriate ARIMA model. The third stage was to combine the prediction results of each IMF and residue to make the predictions. The experimental results indicated that the proposed hybrid EMD-ARIMA framework was capable of predicting short-term freeway traffic speed with high accuracy.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2460-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 3
    Online Resource
    Online Resource
    Pavement Risk Assessment for Future Extreme Precipitation Events under Climate Change
    SAGE Publications ; 2018
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2672, No. 40 ( 2018-12), p. 122-131
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2672, No. 40 ( 2018-12), p. 122-131
    Abstract: Pavement infrastructure is experiencing unanticipated climate conditions caused by global warming. Extreme weather events, such as extreme precipitations, are increasing in intensity and frequency, creating rising concern in pavement vulnerability and resilience analysis. Previous design approaches based on historical climate data may no longer be adequate for addressing future conditions. To promote pavement resilience under climate change, assessing pavement risk for extreme events is essential for prioritizing vulnerable infrastructure and developing adaptation strategies. The objective of this study is to develop a quantitative evaluation methodology for assessing pavement risk from extreme precipitations under climate change. Hazard analysis, fragility modeling, and cost estimation are the three major components for risk evaluation. An ensemble of 24 global climate models is used for predicting future extreme precipitations under various climate-forcing scenarios. The Mechanistic-Empirical Pavement Design Guide is employed to simulate performance change for performing fragility modeling. Risk assessment models considering a full range of hazards were used to quantify risk of asset value loss over specified analysis periods. Results indicate that future extreme precipitation events are expected to cause an increased medium risk of asset value loss. However, high uncertainties are involved in the estimation owing to variations in predicted climates. Major pavement damages do not necessarily equate with highest risk because the probability of occurrence of major damage is relatively lower. The proposed approach provides a practical tool for analyzing the interaction among extreme precipitation levels, pavement designs, damage states, occurrence probability, and asset value at risk.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198118781657
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
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  • 4
    Online Resource
    Online Resource
    Subarea Partition Based on Correlation Analysis with Edge-Elimination Strategy Using Automatic License Plate Recognition Data
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 12 ( 2022-12), p. 641-652
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 12 ( 2022-12), p. 641-652
    Abstract: To partition an urban network into several subareas (i.e., subarea partition) is a vital step for regional coordinated signal control. The correlation between intersections must be analyzed for achieving reliable subarea partition results. However, because of the incompleteness of spatial–temporal information in traffic data, previous studies merely explored the relationship between any intersections. Subarea partition considering the correlation of any pair of intersections remains a challenge in a large-scale network. This paper proposes a subarea partition method that integrates a novel correlation-degree model and the Newman fast algorithm with an edge-elimination strategy using automatic license plate recognition (ALPR) data. First, vehicle trips are extracted and a correlation-degree model is developed for measuring the relationship of any pair of intersections. Second, an edge-elimination strategy is proposed to generate candidate subarea partition solutions under conditions with different proportions of correlated edges. Finally, an optimal solution of subarea partition is identified by the ratios of ideal connected intersections to total intersections of different partition solutions’ correlation index (CI). The proposed method was implemented in a real-world urban network in Kunshan, China. The results show that the optimal partition solution can be obtained when the top 33% of correlated edges are maintained, and the ratio of ideal connected intersections’ CI is 72.35% with most of the intersections being connected, which demonstrates the rationality of the proposed partition method in large-scale urban networks.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221096439
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 5
    Online Resource
    Online Resource
    Pedestrians’ Level of Service at Signalized Intersections in China
    SAGE Publications ; 2009
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2114, No. 1 ( 2009-01), p. 83-89
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2114, No. 1 ( 2009-01), p. 83-89
    Abstract: This paper attempts to develop a level of service (LOS) model for signalized intersection crosswalks for pedestrians in China by using the pedestrians’ perceptions of comfort and safety. First, three potential factors influencing pedestrian LOS at crosswalks are summarized: traffic conflicts, crossing facilities, and delay. Second, collected data for the model include ( a) information on 653 participants’ real-time sense of comfort and safety when crossing 10 selected intersections and ( b) the design and operational characteristics of the selected intersections. The selected crosswalks are typical of those prevalent in urban areas of China, and the participants in the survey covered a broad cross section of the Chinese population of pedestrians. With the survey data, a Pearson correlation analysis and stepwise regression analysis were carried out to develop a reliable pedestrian LOS model for signalized intersections, suitable for use in the vast majority of Chinese urban areas. The study revealed that the factors significantly influencing pedestrian LOS at signalized intersections included right-turning vehicle and bicycle volume from the street parallel to the crosswalk during pedestrian green time, permissive left-turning vehicles and bicycles approaching from the street parallel to the crosswalk, through bicycle volume on the street parallel to the crosswalk, and pedestrians’ delay.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2114-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2009
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  • 6
    Online Resource
    Online Resource
    Microscopic Simulation Model for Pedestrian Flow at Signalized Crosswalks
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2434, No. 1 ( 2014-01), p. 113-122
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2434, No. 1 ( 2014-01), p. 113-122
    Abstract: Signalized crosswalks are considered an important pedestrian facility, where the pedestrian flow possesses unique characteristics. This study used an improved cellular automaton model, which incorporated social forces to describe the interactions between pedestrians, to model the bidirectional pedestrian flow at a crosswalk. The simulation model was capable of estimating crossing time for various levels of pedestrian demand. The observation field data extracted from the video record validated the model's ability to estimate average crossing speed. It also found that pedestrian crossing time and speed are correlated to pedestrian demand. In addition, the proposed model presented the characteristics of pedestrian flow at the crosswalk visually and showed that the interaction between the conflicting flows contributed to an increase in crossing time and a reduction in crossing speed. The benefits of this model can be used to assess the design of signalized crosswalks, including their geometry and pedestrian cycle length.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2434-14
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 7
    Online Resource
    Online Resource
    Development of a Safety Assessment Tool for Long-Span Bridges : Case Study of Sutong Bridge in China
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2451, No. 1 ( 2014-01), p. 97-102
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2451, No. 1 ( 2014-01), p. 97-102
    Abstract: This paper provides a safety assessment tool (SAT) for long-span bridges in China. The authors selected the Sutong Yangtze River Bridge, one of the largest long-span bridges in China, for a case study. Currently, safety assessment of long-span bridges in China is primarily based on human judgment. No effective method exists for estimating the traffic crash risk of long-span bridges under various conditions; this situation creates difficulty in providing effective safety control strategy and developing counter-measures. In this study, the Traffic Software Integrated System was used to simulate the traffic on the Sutong Bridge. A safety assessment model (SAM) was developed from four contributing factors: traffic volume, free-flow speed, percentage of heavy vehicles, and weather conditions. SAM was used as the basis for developing an SAT that could aid policy makers and traffic professionals in better understanding of traffic safety of the Sutong Bridge: (a) a risk map was created to indicate different safety levels of the bridge under various conditions and (b) a user interface was designed to allow users to identify the safety level of the bridge quickly and easily.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2451-11
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 8
    Online Resource
    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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  • 9
    Online Resource
    Online Resource
    Geographic Information System Concept of Operations as a First Step Toward Total Enterprise Asset Management: Metro-North Commuter Railroad Case Study
    SAGE Publications ; 2016
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2540, No. 1 ( 2016-01), p. 111-124
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2540, No. 1 ( 2016-01), p. 111-124
    Abstract: For this enterprise geographic information system (GIS), Metro-North Commuter Railroad Company adopted the concept of operations (ConOps) process to define goals and objectives, inventory existing GIS assets, analyze data gaps, determine “as is” and “to be” business processes, define staffing and resource requirements and project initiatives, and provide a road map for a comprehensive, companywide GIS deployment. In contrast to the top-down approach typically employed in total enterprise asset management (TEAM) planning, Metro-North used a dynamic grassroots approach, holding 14 workshops, which were attended by 92 employees and were designed to collect GIS goals and objectives. The 122 goals generated from this process were distilled into eight companywide goals. These goals included increased efficiency, data sharing, and decision support. Initiatives were developed for five critical business areas that had the potential for demonstrating how enterprise GIS could help Metro-North accomplish its companywide and broader organizational goals. These pilot applications included visualizing straight-line diagrams, integrating property boundary data, retrieving drawings from the capital programs plan room, visualizing train tracking and delays, and visualizing ridership and demographics. This paper shows how a ConOps process could be used in railroad environments to think through GIS-related issues and to define concrete technology projects that provide tangible benefits to user departments and allow them to manage their assets and business issues. Although the focus of this study was on non-asset-related operations within the railroad, the ConOps process offers a user-centric systems planning approach that could be applied to TEAM efforts within the railroad industry or to the planning of corporate initiatives in any business environment.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2540-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
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  • 10
    Online Resource
    Online Resource
    Dynamic Procedure for Short-Term Prediction of Traffic Conditions
    SAGE Publications ; 2002
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1783, No. 1 ( 2002-01), p. 149-157
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1783, No. 1 ( 2002-01), p. 149-157
    Abstract: Many existing models for forecasting traffic conditions are based on traffic flows. Field data are used here to show that these traffic conditions may not fluctuate from day to day in the same manner as does the traffic flow. Consequently, flow data are inappropriate for predicting traffic conditions because the same flow level may correspond to either a congested or a free-flow traffic state, a phenomenon that can be easily explained with the flow–density relationship. Occupancy, which is proportional to density, is a better indicator of traffic condition. A simple dynamic model based on occupancy data is proposed. The model utilizes occupancy and occupancy increments in an integrated way and treats them as two random variables represented by two normal distribution functions. It is shown that flow data, which are more stable than occupancy data, can be used indirectly to improve the performance of the proposed model. Self- and cross-validation efforts are made to examine the performance of the model. The results are promising. The expected absolute deviance for predicted occupancy (ranging from 0 to 100%) is about 1.25%, which is accurate enough for most applications. The model requires little effort in calibration and computation and is exceedingly simple to implement in the field.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1783-19
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2002
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