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  • Mobility and traffic research  (10)
  • 1
    Online Resource
    Online Resource
    Quadrant Roadway Intersections: Tradeoffs between Control Delay Savings and Extra Travel Time
    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: A quadrant roadway intersection (QRI) reduces congestion relative to a four-phase intersection. (Note: this study relates to traffic systems where vehicles drive on the right-hand side of the road.) It does this by removing left-turn traffic from the main intersection, resulting in a two-phase signal. Nevertheless, there is a lack of clear understanding of the tradeoffs between savings in control delay versus extra travel time experienced by the rerouted movements. This research compared the operational performance of five QRI designs with the counterpart conventional intersection (CI) under various traffic demand scenarios via TransModeler microsimulation modeling. Three measures-of-effectiveness (MOEs) were employed: time-in-system (TIS), control delay, and intersection capacity utilization. Simulation results show that all QRI designs outperform CI design for all three MOEs under all demand scenarios. QRIs with direct left-turn design have a smaller average TIS than those with loop left-turn design, indicating that savings in control delays did not offset the extra travel times. Under a relatively low demand condition, a single QRI design can generally balance the tradeoffs between control delay and extra travel time. Under a high demand scenario, a dual or full QRI with direct left-turns is preferred, since it reroutes or partially reroutes left- and right-turn traffic to secondary intersections, thus the main intersection has a lower capacity utilization and can accommodate more through-traffic demands than CI, single QRI, and dual or full QRIs with loop left-turns.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231195056
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 2
    Online Resource
    Online Resource
    Using Longitudinal Mobile Phone Data to Understand the Stability of Individual Travel Patterns : Case Study of Three Communities in Shanghai, China
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2643, No. 1 ( 2017-01), p. 166-177
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2643, No. 1 ( 2017-01), p. 166-177
    Abstract: Most travel demand models assume that individuals’ daily travel patterns are stable or follow a fixed routine. This hypothesis is being questioned by more and more researchers. In this study, longitudinal mobile phone data were used to study the stability of individual daily travel patterns from three aspects, including activity space, activity points, and daily trip-chain patterns. The activity space was represented by the number of nonhome activity points, the radius of nonhome activity points, and the distance from home. The visitation pattern of activity points was analyzed by entropy and predictability measures. The stability of trip-chain patterns was described by the number of distinct trip chains, the typical trip chain, and the typical trip-chain ratio. Analysis of 21 days of mobile phone data from three communities in Shanghai, China, revealed that individuals’ daily travel patterns showed considerable variation. Although individuals’ visitation patterns to activity points were very regular, the day-to-day variations of individual trip-chain patterns were quite significant. On average, an individual exhibited about eight types of daily trip chains during the 21-day period. The daily travel patterns of residents in the outskirts were more stable than those of residents in the city center. Individuals’ travel patterns on weekdays were more complex than those on weekends. As individuals’ activity spaces increased, the stability of their travel patterns decreased.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2643-18
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 3
    Online Resource
    Online Resource
    Two-Step Optimization Model for Dynamic Lane Assignment at Isolated Signalized Intersections
    SAGE Publications ; 2013
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2355, No. 1 ( 2013-01), p. 39-48
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2355, No. 1 ( 2013-01), p. 39-48
    Abstract: At isolated signalized intersections, congestion problems are caused in part by an imbalance in supply and demand, which may be caused by the variability of turning-movement volumes. Although signal timing can be adjusted to handle varying demand, the effect of this adjustment alone is limited, especially when traffic demand fluctuates significantly. A two-step optimization model for dynamic lane assignment is presented: the model overcomes the shortcoming of static lane markings and fully utilizes the existing traffic facilities. The first step is to obtain the best lane assignment scheme by using an arm-group-based integer nonlinear program model. The second step is to identify a suitable implementation scheme by determining a binary-type threshold. The results of VISSIM simulation show that the proposed model can correctly choose the occasion to change the lane assignment by ignoring the small volume fluctuation and can improve traffic operations effectively when the traffic demand varies significantly.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2355-05
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
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  • 4
    Online Resource
    Online Resource
    Laboratory Simulation of Field Compaction Characteristics on Sandy Soils
    SAGE Publications ; 2002
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1808, No. 1 ( 2002-01), p. 84-95
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1808, No. 1 ( 2002-01), p. 84-95
    Abstract: As a result of the development of much heavier earth-moving and vibratory roller compaction equipment, soil compaction densities in the field are reaching levels that are not attainable in the laboratory. Higher compaction efforts, routinely seen in the field, not only result in higher unit weights but also lower optimum moisture contents than those found by the modified Proctor test. An experimental study was undertaken to evaluate field and laboratory compaction characteristics and to study laboratory compaction techniques further, such as gyratory compaction, in addition to impact and vibratory compaction, for the laboratory simulation of field compaction of A-3 sandy soils. Field test sections were constructed using typical field compaction techniques of today. Earth pressure cells were installed at the base of each lift to monitor total vertical stresses. A series of laboratory gyratory compaction tests for A-3 soils were conducted. Factors including vertical pressure, gyration angle, and gyration numbers were evaluated for the effects on the dry unit weight. The gyratory compaction curves using 200-kPa (29 psi) vertical pressure, a 1.25-degree gyration angle, and 90 gyrations were close to the field compaction curves.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1808-10
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2002
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  • 5
    Online Resource
    Online Resource
    Location-Based Social Networking Data : Exploration into Use of Doubly Constrained Gravity Model for Origin–Destination Estimation
    SAGE Publications ; 2014
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2430, No. 1 ( 2014-01), p. 72-82
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2430, No. 1 ( 2014-01), p. 72-82
    Abstract: Trip distribution is an invaluable portion of the transportation planning process; this distribution leads to the creation of origin–destination (O-D) matrices. Location-based social networking (LBSN) has increased in popularity and sophistication and has emerged as a new travel demand data source. Users of LBSN provide location-sensitive data interactively with mobile devices, including smartphones and tablets. These data can provide O-D estimates with significantly higher temporal resolution at a much lower cost in comparison with traditional methods. An LBSN O-D estimation model based on the doubly constrained gravity model was proposed to improve a previously proposed model based on the singly constrained gravity model. The proposed methodology was calibrated and comparatively evaluated against the O-D matrix generated by the method based on the singly constrained gravity model as well as a reference matrix from the local metropolitan planning organization. The results of this method illustrate significant improvement in reducing the O-D estimation errors caused by the sampling bias from the method based on the singly constrained gravity model.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2430-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
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  • 6
    Online Resource
    Online Resource
    Bi-Level Model for Design of Transit Short-Turning Service Considering Bus Crowding
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2649, No. 1 ( 2017-01), p. 52-60
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2649, No. 1 ( 2017-01), p. 52-60
    Abstract: A bi-level model was developed to design the short-turning strategy on a bus route. The upper-level model aimed at minimizing the total cost, including operational cost, passengers’ waiting time cost, and in-vehicle travel time cost. The lower-level model was a logit model to capture the service choices of passengers. The effects of bus crowding and seat availability were considered explicitly in the proposed model. An algorithm was developed to determine the frequencies of different services and the turnback points of the short-turning service. A case study demonstrates the superiority of the proposed model over alternative models. Sensitivity of the optimal design to seat capacity was also investigated.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2649-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 7
    Online Resource
    Online Resource
    Increasing the Capacity of Signalized Intersections with Dynamic Use of Exit Lanes for Left-Turn Traffic
    SAGE Publications ; 2013
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2355, No. 1 ( 2013-01), p. 49-59
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2355, No. 1 ( 2013-01), p. 49-59
    Abstract: Many congested intersections have a heavy traffic volume on movements for which capacity is insufficient because of geometric limitations. An unconventional approach that increases the capacity of heavily congested intersections is presented: this approach opens up exit lanes for left-turn traffic dynamically with the help of an additional traffic light installed at the median opening (the presignal); this situation is referred to as exit lanes for left-turn (EFL) control. An optimization problem for EFL control was formulated as a mixed-integer nonlinear program, in which the geometric layout, main signal timing, and presignal timing were integrated. The mixed-integer nonlinear program was solved by transformation into a series of mixed-integer linear programs. The latter problem can be solved with the standard branch-and-bound technique. The results of extensive numerical analysis and VISSIM simulation showed that the EFL approach could increase intersection capacity and reduce traffic delay substantially, especially under high left-turn demand. Moreover, the EFL control can be applied to one or multiple legs simultaneously; thus the control is particularly useful for intersections with an unbalanced left demand and a degree of saturation in travel directions.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2355-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
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  • 8
    Online Resource
    Online Resource
    Automatic Vehicle Identification Technology Applications to Toll Collection Services
    SAGE Publications ; 1997
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1588, No. 1 ( 1997-01), p. 18-25
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1588, No. 1 ( 1997-01), p. 18-25
    Abstract: Intelligent transportation systems technologies are being developed and applied through transportation systems in the United States. An example of this type of innovation can be seen on toll roads where a driver is required to deposit a toll in order to drive on a toll road. To automatically process toll services, automatic vehicle identification (AVI) technologies should be developed and implemented. A summary is presented of a study that focused on the performance analysis of three types of AVI technologies that could be used for toll collection applications on the Crosstown Expressway and the Veterans Expressway in Hillsborough County, Florida. The three AVI technology types were optical/laser scanner, radio frequency, and inductive loop. The study aimed at analyzing the total average delay and AVI market share due to the usage of AVI technologies. Delay performance and market share resulting from the application of each AVI technology type were used to compare the effects of different AVI technology types. The analysis was based on computer simulation using an AVI lane choice model (demand model) and a delay model (performance model) with the data collected from the two toll roads in Hillsborough County. From the simulation results, a cost-benefit analysis was performed to evaluate the impacts of AVI technologies on the ratio of benefit over cost. Results of the cost-benefit analysis can be used to determine the optimal configuration of AVI lanes and manual lanes. A procedure is provided that can be used for planning and designing AVI technologies used in toll service.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1588-03
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1997
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  • 9
    Online Resource
    Online Resource
    Bidirectional Control Characteristics of General Motors and Optimal Velocity Car-Following Models : Implications for Coordinated Driving in a Connected Vehicle Environment
    SAGE Publications ; 2013
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2381, No. 1 ( 2013-01), p. 110-119
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2381, No. 1 ( 2013-01), p. 110-119
    Abstract: In natural traffic flow, the information from preceding vehicles predominantly determines driver behavior. With connected vehicle technologies, drivers can receive information from both preceding and following vehicles. This information creates new opportunities for vehicle coordination and control at the microscopic level on the basis of bidirectional information. Although bidirectional car-following models have been studied since the 1960s, most existing car-following models, especially those used by adaptive cruise control technologies, are still forward-only car-following models. This paper serves as a first step toward the use of bidirectional car-following models for microscopic vehicle coordination and control. The focus is on the study of the models' general control characteristics and impact on traffic flow stability. A general bidirectional control framework is proposed to convert any car-following model into its bidirectional form. Four representative General Motors and optimal velocity car-following models are reformulated and calibrated against field vehicle trajectory data collected in the next-generation simulation program (NGSIM). The bidirectional control characteristics of the selected models were evaluated by tuning of the percentage of backward information considered in the final car-following decision. The evaluation uses forward versus backward acceleration diagrams and a ring road stability analysis of equilibrium states obtained from NGSIM data. The results indicate that the increase in the contribution of backward information may help alleviate traffic congestion and stabilize traffic flow. An operating range of the backward information contribution of between 5% and 20% is recommended to ensure that the resulting models are still physical and realistic for both free-flow and congestion situations.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2381-13
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
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  • 10
    Online Resource
    Online Resource
    Interactive COVID-19 Mobility Impact and Social Distancing Analysis Platform
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 4 ( 2023-04), p. 168-180
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 4 ( 2023-04), p. 168-180
    Abstract: The research team has utilized privacy-protected mobile device location data, integrated with COVID-19 case data and census population data, to produce a COVID-19 impact analysis platform that can inform users about the effects of COVID-19 spread and government orders on mobility and social distancing. The platform is being updated daily, to continuously inform decision-makers about the impacts of COVID-19 on their communities, using an interactive analytical tool. The research team has processed anonymized mobile device location data to identify trips and produced a set of variables, including social distancing index, percentage of people staying at home, visits to work and non-work locations, out-of-town trips, and trip distance. The results are aggregated to county and state levels to protect privacy, and scaled to the entire population of each county and state. The research team is making their data and findings, which are updated daily and go back to January 1, 2020, for benchmarking, available to the public to help public officials make informed decisions. This paper presents a summary of the platform and describes the methodology used to process data and produce the platform metrics.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981211043813
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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