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  • Mobility and traffic research  (19)
  • 1
    Online Resource
    Online Resource
    Using Trajectory Data to Analyze Intradriver Heterogeneity in Car-Following
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2188, No. 1 ( 2010-01), p. 85-95
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2188, No. 1 ( 2010-01), p. 85-95
    Abstract: This paper presents a methodology for using vehicle trajectory data to study the intradriver heterogeneity of driving behavior between the acceleration process and the deceleration process. Trajectory data were collected during peak hours on Dutch Motorway A2. Criteria were proposed for the selection of subtrajectories corresponding to both the acceleration and the deceleration processes of car-following. With the application of these subtrajectories to calibrate three types of models (the Helly model, the Gipps model, and the intelligent driver model), it was found that obvious intradriver heterogeneities existed in driving behaviors between the acceleration and deceleration processes of car-following: (a) the average response time of drivers in the acceleration process was longer than that in the deceleration process according to the prediction of the Helly and intelligent driver models; (b) drivers were apt to respond more intensively to surrounding traffic in the deceleration process than they did in the acceleration process; and (c) more than 65% of drivers involved in this study drove in obviously different styles between the acceleration and deceleration processes. Moreover, a compensation for the response delay from model parameters was observed, and all three models presented low robustness in predicting driving behaviors of one car-following process with the parameters optimized from the data of other car-following processes. This work not only provides insight into intradriver heterogeneity in car-following behaviors but also suggests some important criteria for car-following modeling.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2188-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
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  • 2
    Online Resource
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    General Newell Model and Related Second-Order Expressions
    SAGE Publications ; 2011
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2260, No. 1 ( 2011-01), p. 42-49
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2260, No. 1 ( 2011-01), p. 42-49
    Abstract: A general Newell model that considers the anticipation behaviors of drivers is presented. The model contains a new parameter called the anticipation factor. Three types of car-following models are derived from the general Newell model as second-order expressions. Two types of derived models are consistent with the full velocity difference model. All three types of derived models can be transformed to the optimal velocity model when the anticipation factor equals zero. It is found that the speed difference term in the full velocity difference model reflects the anticipation behaviors of drivers. The vehicle trajectory data of the Dutch A2 motorway are used to calibrate the models. The results of model calibrations are the basis for investigation of the distributions of the time lag and the anticipation factor among the driver population. The parameters of the three proposed models present good correlations between each other. A numerical simulation is conducted to explore the properties of the proposed models when applied in the adaptive cruise control system. Both the proposed Type I model (the full velocity difference model) and the proposed Type III model present good performance in controlling vehicles moving along the optimal trajectory, especially when the anticipation factors of the models are set to one.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2260-05
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2011
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  • 3
    Online Resource
    Online Resource
    Experimental Features and Characteristics of Speed Dispersion in Urban Freeway Traffic
    SAGE Publications ; 2007
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1999, No. 1 ( 2007-01), p. 150-160
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1999, No. 1 ( 2007-01), p. 150-160
    Abstract: Characteristics of speed dispersion in urban freeway traffic are presented. Two definitions of speed dispersion are proposed: the standard deviation of the individual speeds and the average speed difference of two neighboring vehicles. On the basis of the definitions, traffic data obtained from two urban freeways in China are studied, and different characteristics of speed dispersion are found in four substates of traffic flow, which correspond to four regions in the empirical fundamental diagram. In the bunching state of congested traffic, the flow rate decreases with an increase in speed dispersion at a given mean speed. In the bunching state of fluid traffic, the speed dispersion of traffic flow is small, and in the free state of fluid traffic, speed dispersion is distributed in a disorderly manner in a wide range. Such phenomena are more remarkable under the definition of the average speed difference for speed dispersion. In addition, some possible explanations are presented for the characteristics of speed dispersion in each traffic substate. These speed dispersion studies provide a new approach for microscopic modeling and understanding of traffic flow characteristics.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1999-16
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2007
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  • 4
    Online Resource
    Online Resource
    Effect of Mixing Time and Temperature on the Homogeneity of Asphalt Mixtures Containing Reclaimed Asphalt Pavement Material
    SAGE Publications ; 2018
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2672, No. 28 ( 2018-12), p. 167-177
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2672, No. 28 ( 2018-12), p. 167-177
    Abstract: Laboratory-produced reclaimed asphalt pavement (RAP) material, new aggregate, and tinted new binder were mixed (RAP proportion: 40%) with 12 different combinations of mixing temperatures and times, based on which circular specimens of various thicknesses were fabricated and then subjected to multi-direction indirect tensile stiffness modulus (ITSM) testing and color image analysis. Statistical calculations including average value, coefficient of variation, standard deviation, and range were carried out to investigate the effects of different mixing conditions on the homogeneity of asphalt mixtures containing RAP. The results show that the deterioration of homogeneity of asphalt mixtures containing RAP was mainly caused by the asynchronous breaking of clusters. The mixing temperature was decisive in determining the resistance of clusters to breaking, and for mixing conditions chosen in this study, the resistance increases with the increase of mixing temperature. Short mixing time might lead to a phenomenon of “momentary homogeneity,” in which clusters were not broken and the blending degree between aged and new binder was low.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198118796967
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
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  • 5
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    Online Resource
    Road Piezoelectric Power Output Model and Experimental Study under Bidirectional Vehicle Load Excitation
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    Details
    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
    URL: Article
    DOI: 10.1177/03611981231192984
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 6
    Online Resource
    Online Resource
    Analyzing Travelers’ Intention to Accept Travel Information : Structural Equation Modeling
    SAGE Publications ; 2010
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2156, No. 1 ( 2010-01), p. 93-100
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2156, No. 1 ( 2010-01), p. 93-100
    Abstract: Advanced traveler information systems (ATIS) cannot improve the traffic environment if travelers do not accept the travel information provided by the system. To understand better why travelers accept or refuse travel information and to explain, predict, and increase travelers’ acceptance of travel information, a research framework based on the technology acceptance model is developed to establish the relationship between travelers’ intention to accept travel information, trust in travel information, perceived usefulness of travel information, perceived ease of its use, and other related variables. Then structural equation modeling is used to examine and analyze the relationship among these variables. The results show that the factors that significantly determine travelers’ intention to accept travel information are trust in travel information, its perceived usefulness, its perceived ease of use, and information attributes. Through an examination of the direct, indirect, and total effects in the model system, it is discovered that perceived ease of use has the largest total effect on intention to accept by a standardized coefficient of 0.522, followed by trust in information (0.348), perceived usefulness (0.199), and information attributes (0.079). These results indicate the practical value of the estimated model for guiding recommendations aimed at increasing travelers’ intention to accept travel information and at improving the service quality of travel information in China.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2156-11
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2010
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  • 7
    Online Resource
    Online Resource
    Estimating Truck-Rollover Crashes on Ramps by Using a Multistate Database
    SAGE Publications ; 1999
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1686, No. 1 ( 1999-01), p. 29-35
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1686, No. 1 ( 1999-01), p. 29-35
    Abstract: Currently, among other intelligent transportation system applications, there is an increased interest in using an “in-vehicle warning system” to mitigate truck-rollover crashes on interchange ramps. Because the cost of installing the system in an entire truck fleet would be significant, a basic question is how large a safety problem is addressed. This study was an attempt to estimate the annual national frequency and cost of large-truck accidents on interchange ramps that result in rollovers. Using tabular analysis of a five-state database, the estimate was that approximately 11 percent of total truck involvements are on interchange ramps and that between 44 and 52 percent of the incidents result in rollovers. Both urban and rural locations present significant problems that could be addressed by an in-vehicle warning system. Combining this information with General Estimates System figures for total national truck crashes, it is estimated that there are between 4,400 and 5,000 truck rollovers on ramps each year nationwide. The annual economic cost of these rollovers is between $405 million and $460 million. These data provide both information to safety engineers on the size of a significant truck safety problem and a base for a meaningful cost-benefit analysis of installing the in-vehicle warning system. Although available data do not allow a detailed cost-benefit analysis, a simplified analysis of “breakeven costs” indicates that such a device is highly dependent on the level of effectiveness, ranging from approximately $300 per truck to $3,200 per truck.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1686-05
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1999
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  • 8
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    Operating-Speed Model for Low-Speed Urban Tangent Streets Based on In-Vehicle Global Positioning System Data
    SAGE Publications ; 2006
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1961, No. 1 ( 2006-01), p. 24-33
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1961, No. 1 ( 2006-01), p. 24-33
    Abstract: Low-speed urban streets are designed to provide both access and mobility and to accommodate multiple road users, such as bicyclists and pedestrians. However, speeds on these facilities often exceed the intended operating speeds, as well as their design speeds. Several studies have indicated that the design speed concept, as implemented in the roadway design process in the United States, does not guarantee a consistent alignment promoting uniform operating speeds less than design speeds. A promising design approach to overcome these apparent shortfalls of the design speed approach is a performance-based design procedure with the incorporation of operating speeds. However, this approach requires a clear understanding of the relationships between operating speeds and various road environments. Although numerous previous studies have developed operating-speed models, most of these studies have concentrated on high-speed, rural two-lane highways. In contrast, highway designers and planners have little information about the influence of low-speed urban street environments on drivers’ speeds. This study investigated the relationship between drivers’ speed choices and their associated low-speed urban roadway environments by analyzing second-by-second in-vehicle global positioning system (GPS) data from more than 200 randomly selected vehicles in the Atlanta, Georgia, area. The authors developed operating-speed models for low-speed urban street segments on the bases of roadway alignment, cross-section characteristics, roadside features, and adjacent land uses. The results of this research effort can help highway designers and planners better understand expected operating speeds when they design and evaluate low-speed urban roadways.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198106196100104
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
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  • 9
    Online Resource
    Online Resource
    Normal Deceleration Behavior of Passenger Vehicles at Stop Sign–Controlled Intersections Evaluated with In-Vehicle Global Positioning System Data
    SAGE Publications ; 2005
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1937, No. 1 ( 2005-01), p. 120-127
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1937, No. 1 ( 2005-01), p. 120-127
    Abstract: Deceleration characteristics of passenger cars are often used in traffic simulation, vehicle fuel consumption and emissions models, and intersection and deceleration-lane design. Most previous studies collected spot speed data with detectors or radar guns. Because of the limitations of the data collection methods, these studies could not determine when and where drivers began to decelerate. Therefore, the studies may not provide an accurate estimation of deceleration time and distance. Furthermore, most previous studies are based on outdated and limited data, and their conclusions may not be applicable to the current vehicle fleet and drivers. The normal deceleration behavior of current passenger vehicles is evaluated at stop sign–controlled intersections on urban streets on the basis of in-vehicle Global Positioning System data. This study determined that drivers with higher approach speeds decelerated over a longer time and distance. Higher initial deceleration rates were also associated with higher approach speeds. However, the collected data in this study did not indicate a clear relationship between the average and maximum deceleration rates and approach speeds. With second-by-second deceleration profile data, the authors found that most drivers reached their maximum deceleration rates about 5 s or less than 5 s before stopping, and the maximum deceleration rate (3.4 m/s 2 ) recommended by AASHTO was applicable to most of the study drivers. This review verified several previous deceleration models with the current observations and found that the polynomial model developed by Akcelik and Biggs provides the best fit for the data set in this study. Finally, this study developed a new deceleration model based on the approach speeds and deceleration time.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198105193700117
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2005
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  • 10
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    Factors Associated With the Severity of Motor Vehicle Crashes Involving Electric Motorcycles and Electric Bicycles: A Random Parameters Logit Approach With Heterogeneity in Means
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 691-704
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 691-704
    Abstract: Exploring the heterogeneity of factors influencing the severity of electric bicycle crashes and electric motorcycle crashes can help target accident prevention policies to improve traffic safety. Therefore, this paper establishes a mean heterogeneity random parameter logit model using crash data from 2016 to 2020 in Guangxi to explore the different factors influencing the severity of crashes involving electric motorcycles and electric bicycles. The results show that the key influences on crash severity differ in electric motorcycle crashes and electric bicycle crashes. At the same time, some common factors affect the two types of crashes to different degrees. In addition, the complex interaction effects of unobserved heterogeneity were considered to explore the random parameters of the two types of crashes. The effect of unobserved heterogeneity on the distribution characteristics of the random parameters was then determined. For example, in electric motorcycle crashes, street lighting at night has a random parameter characteristic. The likelihood of serious crashes decreased when both street lighting at night and vehicle left turn were involved, and decreased when both street lighting at night and no signal control were involved. In electric bicycle crashes, large trucks have a random parameter characteristic. The likelihood of serious crashes increased when both large trucks and motor vehicle lights not turned on were involved, and increased when both large trucks and visibility less than or equal to 200 meters were involved. The results provide a basis for improving the road safety of electric motorcycles and electric bicycles.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231157716
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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