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  • Mobility and traffic research  (11)
  • 1
    Online Resource
    Online Resource
    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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  • 2
    Online Resource
    Online Resource
    Vehicle Load Effect of Long-Span Bridges : Assessment with Cellular Automaton Traffic Model
    SAGE Publications ; 2015
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2481, No. 1 ( 2015-01), p. 132-139
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2481, No. 1 ( 2015-01), p. 132-139
    Abstract: Vehicle load is one of the primary live loads for long-span bridges. However, load distribution and composition are complicated on long-span bridges and vary significantly. In general, bridge codes do not include specifications for bridges with long spans. In this study, the microscale traffic model, cellular automaton (CA) model, was adopted to establish a long-span vehicle load model through a merger with real-monitored traffic data. The differences in the current design vehicle loads used in China, the United States, Great Britain, and Europe are discussed. The effects of the CA load with different vehicle density and vehicle composition were estimated for loaded lengths from 100 to 1,000 m with the influence line. The largest moment of a bridge from a CA load was compared with that of the design vehicle load statistically. The results showed that vehicle density, loaded length, and the heavy truck percentage were the main features of the vehicle loading effects. An increase in vehicle density led to higher average and extreme values for the loading effect. When the loaded length was more than 600 m, the impact of the loaded lengths vanished. When the vehicle density was the same, a heavy percentage of truck traffic had a significant impact on the loading effect. Moreover, when the percentage of heavy trucks was high, the design load for relatively shorter loaded lengths needed to be adjusted because the current design load safety margin for a loaded length of not more than 300 m was small.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2481-17
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2015
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  • 3
    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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  • 4
    Online Resource
    Online Resource
    Simulation Tool to Assess Impacts of Parameters of Service Patrol Operations
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2178, No. 1 ( 2010-01), p. 111-118
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2178, No. 1 ( 2010-01), p. 111-118
    Abstract: Freeway service patrol (FSP) programs constitute one of the most popular elements of intelligent transportation systems and have been increasingly implemented around the United States. Despite the successes and the benefits of these programs, however, recent budget cuts have increased the need to demonstrate the benefits of the programs, to show the differences in the benefits of different operation schedules, and to select the parameters of the operations to make the best use of available resources. This paper reports on an effort to develop a tool (a) to assess the performance of FSPs under different operation parameters and the impacts of FSP performance on transportation network measures and (b) to select operation parameters. The tool was developed by means of a general purpose simulation modeling environment. The output from the simulation is fed into a spreadsheet that allows assessment of changes in incident durations on transportation network performance in terms of delays, fuel consumption, emission, safety, and dollar values. The applications of the tool indicate that it can be used to assess FSP operation parameters and the systemwide and economic impacts of changing these parameters.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2178-12
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
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  • 5
    Online Resource
    Online Resource
    Quantitative Assessment on Navigation Impact of the Controlled Waterway in the Upper Yangtze River Using Queuing Model
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 4 ( 2022-04), p. 421-435
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 4 ( 2022-04), p. 421-435
    Abstract: As an important transportation link between eastern and western economic zones of China, the Yangtze River waterway has been globally ranked first in relation to freight volume since 2010, and the density of ship traffic has also increased significantly. However, the inland navigation system has been increasingly threatened by traffic congestion, which is more serious in the controlled waterways of the upper Yangtze River. In this study, the distribution laws of ship traffic flow and service time in the controlled waterway were analyzed, indicating that the traffic flow obeys the Poisson distribution, and the service time obeys a negative exponential distribution. Thereafter, by simplifying the queuing processes and rules, the M/M/1 queuing service model was established to calculate ship queuing indicators in a controlled waterway. It was found that the ship queuing indicators varied greatly among different controlled waterways. Compared with downstream ships, upstream ships usually had longer queuing lengths and times, which were also more affected by the increasing number of ship arrivals and service times. Consequently, a dimensionless loss coefficient was proposed to quantify the influence of the controlled waterway on the navigation capacity. As the service time and number of ships increased, the loss coefficient also increased. The results of this study could provide references for understanding the ship queuing problem, and thereby the assessment of navigation capacity and anchorage constructions in a controlled waterway.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211061127
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 6
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    Online Resource
    Data Verification Methodology to Facilitate Employment Database Updates for Transportation Planning
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 5 ( 2022-05), p. 560-570
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 5 ( 2022-05), p. 560-570
    Abstract: Researchers on travel behavior and regional economic trends increasingly rely on multiple data sources to locate employers and site-specific employment. In a previous study, we proposed a method to assess and integrate multiple sources of employment data using three components: the Google Places application programming interface (API), a business existence verification model, and manual reviews of sampled data. This paper updates our previous methodology with a dual conditional classification of incoming and previously verified employment data made possible by checks using Google Places API and two rounds of string comparisons for both business names and establishment locations. The resulting match classes distinguish well-matched or confirmed business listings from those that require additional review to evaluate potential business closure or relocation. This screening process, augmented with fuzzy logic string matching techniques, reduces the effort needed to update employer information and assists with automated data standardization and deduplication, integrating incoming employment information with a database of verified employers.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221090243
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
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  • 7
    Online Resource
    Online Resource
    Mechanistic–Empirical Pavement Design Guide–Based Pavement Design Catalog for Low-Volume Roads in Arkansas
    SAGE Publications ; 2011
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2203, No. 1 ( 2011-01), p. 169-177
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2203, No. 1 ( 2011-01), p. 169-177
    Abstract: Historically, low-volume roads in Arkansas were typically constructed by use of a standard section, that is, a double surface treatment over a specified thickness of granular base. Subsequent analysis indicated that these sections were structurally inadequate in many cases. In recent years, the Arkansas State Highway and Transportation Department has invested significant research dollars to implement the Mechanistic–Empirical Pavement Design Guide (MEPDG), which is widely believed to be a quantitative leap over the 1993 AASHTO design guide. However, the MEPDG research efforts mostly target high-volume roads. In this paper, a design catalog for low-volume roads (LVRs) in Arkansas was developed with MEPDG software, Version 1.10. The catalog offers a variety of feasible design alternatives for a comprehensive combination of site conditions. The factors considered include the five geographical regions in Arkansas and the typical Arkansas load spectrum for LVRs with three traffic levels, three subgrade types, and six potential aggregate types available in Arkansas that can be used as granular base and surface layer aggregates. All the MEPDG design inputs needed for the development of the design catalog are generated on the basis of the variety of previous MEPDG implementation research conducted in the state of Arkansas. It is anticipated that the design catalog will serve as a simplified and rational design process for the LVRs in Arkansas.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2203-21
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2011
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  • 8
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    Resurrecting the Lost Vehicle Trajectories of Treiterer and Myers with New Insights into a Controversial Hysteresis
    SAGE Publications ; 2018
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2672, No. 20 ( 2018-12), p. 25-38
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2672, No. 20 ( 2018-12), p. 25-38
    Abstract: The 1974 paper by Treiterer and Myers is a seminal work in traffic flow theory. This longevity is in part because of the impressive collection of manually extracted vehicle trajectories. To date, only a few studies have rivaled the scale of the empirical vehicle trajectory data used in Treiterer and Myers. Their data collection used high-speed aerial photography and manual data reduction to follow hundreds of vehicles. In spite of the Herculean collection effort, the trajectory data set was never released and has since been lost. Fortunately, the plots survive and the present work re-extracts the vehicle trajectory data from the time–space diagrams. The discussion places the value of the data in context and then uses the data to put an end to decades of misinterpretation that started with Treiterer himself. The central thesis of Treiterer and Myers generated considerable interest: a hysteresis whereby drivers exhibit different fundamental behavior depending on whether they are entering or exiting a disturbance. There has been extensive debate about the authors’ findings in the literature, but without the original data set any interpretation has required considerable speculation. With the resurrected trajectories, this work reexamines the vehicles underlying the hysteresis and finally quells the speculation. Rather than arising from car following behavior, it turns out that the enigmatic progression arose from a combination of lane change maneuvers and unremarkable transitions into or out of the congested regime. On publication, the re-extracted data from this paper will be released to the research community.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198118786473
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
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  • 9
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    Innovative Soft Soil Stabilization Using Simultaneous High-Vacuum Dewatering and Dynamic Compaction
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2186, No. 1 ( 2010-01), p. 138-146
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2186, No. 1 ( 2010-01), p. 138-146
    Abstract: A combination of the high-vacuum (HV) and dynamic compaction (DC) method (HV+DC method) was used to improve saturated soft foundation. HV and DC were applied alternately and repeatedly to achieve the required level of ground improvement. An in-depth investigation was conducted of the technical requirements, processes, and mechanisms involved in the HV+DC method at the Ningbo Harbor Coal test site near Shanghai, China. Relevant drainage control parameters were identified and optimized to provide the construction parameters, such as compaction energy, spacing, drop number, vacuum dewatering number and location, and wellpoint depth and number, for large area construction. The monitoring during the field trial case study presented here indicates that the method is not only based on sound concepts with rapid stabilization effects and low construction costs but also holds significant promise as an innovative ground improvement method when soft soils are encountered. The application of the HV+DC method increased the cone penetration tip resistance q t of the pond fly ash layer at the Ningbo site more than 2.5 times and that of the clay mud layer more than 1.5 times (compared with unmodified ground) and improved the characteristic value of the bearing capacity of the foundation up to 135 kPa, all of which adequately met the design requirements. For the total area of 400,000 m 2 of the main project, this innovative method has saved more than 40% of total cost and approximately 50% of construction time from the original design of the soil cement mixing method.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2186-15
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
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  • 10
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    Impact of Cooperative Adaptive Cruise Control on a Multilane Highway under a Differentiated Per-Lane Speed Limit Policy
    SAGE Publications ; 2021
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2675, No. 10 ( 2021-10), p. 353-366
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2675, No. 10 ( 2021-10), p. 353-366
    Abstract: Cooperative adaptive cruise control (CACC) has drawn wide attention in recent years for its potential throughput benefit, as it is a promising intermediate technology to the highly connected and automated vehicles. The impact of CACC on multilane highways has been the subject of several studies, but they assumed traffic under a uniform speed limit. Recent research has revealed that traffic performs differently under a differentiated per-lane speed limit (DPLSL) policy with heavy vehicle (HV) restricted lanes. Whether the benefits of CACC still remain under a DPLSL policy has not been explored. This study developed cellular automaton models to incorporate CACC-equipped and non-equipped vehicles (i.e., passenger cars, HVs) on a two-way eight-lane highway with a DPLSL. Results shown throughputs by lane increase up to 78.5% as the CACC car market penetration rate (MPR) rises. Such increases became sharper (i.e., ≥10%) for inner lanes (i.e., HV restricted lanes) and outer lanes after reaching a 40% and a 60% CACC car MPR, separately. Moreover, HVs induced a 1.5% to 15.7% throughput reduction across lanes even under higher CACC car MPRs (i.e., 60%, 80%). This DPLSL policy may cause the lanes to experience a throughput penalty when they are adjacent to lanes with a different speed limit as the MPR of CACC cars rises. Lastly, in traffic with a 60% CACC car MPR, increases are brought further by considering 10% of HV with CACC, especially on those HV non-restricted lanes. The study is helpful for policy makers to further prepare for the prevalence of CACC in the forthcoming years.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211011475
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
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