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  • Mobility and traffic research  (51)
  • 1
    Online Resource
    Online Resource
    Microscopic Simulation Approach to Effectiveness Analysis of Transit Signal Priority for Bus Rapid Transit : A Case Study in Beijing
    SAGE Publications ; 2008
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2072, No. 1 ( 2008-01), p. 64-76
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2072, No. 1 ( 2008-01), p. 64-76
    Abstract: Transit signal priority (TSP) is one of the critical components of bus rapid transit (BRT) and a key technology in enhancing its operational efficacy. It not only provides priority to the BRT vehicle but also manages the trade-off between the delay of buses at an intersection and the impacts on other traffic. This paper focuses on the design and evaluation of a simulation of signal priority for BRT under mixed traffic flow conditions. Taking the Southern Axis BRT Line 1 in Beijing as a case study, different signal priority strategies, including green extension, red truncation, and special phase insertion, are developed for the signalized intersection along the BRT route. A signal coordination plan is designed for the section composed of four intersections in the BRT system. The study uses the VISSIM microscopic traffic simulation model to analyze the impacts of traffic parameters, especially those of nonmotorized traffic, on the effectiveness of TSP along the corridor. Simulation results indicated that the BRT vehicles would typically benefit from transit priority with travel times savings and delay reduction, as well as greater schedule adherence, and suggest that these benefits may be obtained with little negative impacts to the overall system. The results also indicated that the volume of nonmotorized traffic is one of the most important factors that influence the effectiveness of TSP implementation in a mixed traffic flow.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2072-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2008
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    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
    detail.hit.zdb_id: 2403378-9
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  • 3
    Online Resource
    Online Resource
    Dynamic Programming Model for Attended Delivery Time Slot Management
    SAGE Publications ; 2016
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2548, No. 1 ( 2016-01), p. 43-52
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2548, No. 1 ( 2016-01), p. 43-52
    Abstract: Offering customers the choice of delivery time slots is an emerging business strategy in attended home delivery service because this option has the potential to improve service level and reduce the risk of delivery failure. A dynamic programming model was developed for assisting attended delivery service providers with pricing decisions in managing time slots. Since the choice of delivery time slots involves both marketing and operational issues, a proposed dynamic pricing model maximizes the total system expected revenue while also improving the matches between customers’ and service providers’ preferred time slots and fees. The study started by managing homogeneous time slots with three kinds of customer behaviors (i.e., price taker, price negotiator, and leave-without-pay) and then considered heterogeneous time slots. The study found that the optimal price might vary depending on customers’ arrival rates in the system, the remaining capacities of available time slots, the percentages of customers who are price negotiators, and the time left in the sales periods.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2548-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
    detail.hit.zdb_id: 2403378-9
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  • 4
    Online Resource
    Online Resource
    Cyclic Performance of Precast Concrete Segmental Bridge Columns : Simplified Analytical and Finite Element Studies
    SAGE Publications ; 2006
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1976, No. 1 ( 2006-01), p. 66-74
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1976, No. 1 ( 2006-01), p. 66-74
    Abstract: The cyclic performance of an unbonded precast concrete segmental bridge column system is examined in this paper. This system uses unbonded posttensioning to enhance the self-centering capability and mild steel reinforcement extended across the segment joints to enhance the energy dissipation capability. A simplified analytical method for the system under lateral load is established, and the simplified analytical results are compared with those obtained from the three-dimensional (3-D) finite element method (FEM). On the basis of the simplified analytical method, suggestions are made about both the height of the column to which the mild steel should be continued from the foundation and the limitation of the steel ratio to minimize residual displacement. With the steel ratio varied, the correlation between the energy dissipation capability and the self-centering capability of this system is investigated by means of the 3-D FEM. From simulation results, it was found that both the energy dissipation and the residual displacement increase as the steel ratio increases. It was also found that the system with a steel ratio suggested by the proposed equation resulted in a significant increase in energy dissipation compared with the one without mild steel across the joints, while the recommended system maintained a small residual displacement after loading reversals.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198106197600108
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
    detail.hit.zdb_id: 2403378-9
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  • 5
    Online Resource
    Online Resource
    Boarding and Alighting Experiments : Overview of Setup and Performance and Some Preliminary Results
    SAGE Publications ; 2008
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2042, No. 1 ( 2008-01), p. 71-81
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2042, No. 1 ( 2008-01), p. 71-81
    Abstract: Vehicle dwell time is an important determinant of the system performance and passenger service quality of public transport systems. Adequate prediction models for vehicle dwell time are required in timetable planning and in pedestrian simulation tools to optimize station design and rolling stock design. Because most of the dwell time is consumed by boarding and alighting, this paper focuses on increasing insight into boarding and alighting behavior in railroad vehicles by performing laboratory experiments using video cameras. The experiments test the effects of the physical environment (stepping gap, height difference, and door width), population (age, gender), flow composition (direction, time pressure, luggage, boarding group size, boarding ratio, queuing discipline), and prevailing traffic conditions (crowding on board and crowding on the platform). From the video images, pedestrian trajectories (movements over time) have been derived. This paper describes the effects of the size of the horizontal and vertical gap and the presence of luggage on the door capacity. Door capacities have been estimated by using headway distributions and cumulative curves. Increasing the horizontal and vertical gap leads to decreases in the capacity (up to 15%). When passengers with luggage (suitcases) are present, the capacity decreases more (up to 25%).
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2042-08
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2008
    detail.hit.zdb_id: 2403378-9
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  • 6
    Online Resource
    Online Resource
    Scheduling of Feeder Vehicles for Intermodal Services for Special Events
    SAGE Publications ; 2011
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2216, No. 1 ( 2011-01), p. 165-173
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2216, No. 1 ( 2011-01), p. 165-173
    Abstract: During special events, shuttle services provided by a feeder bus system can be very useful for providing passengers access to the mass rapid transit system, especially passengers in suburban areas where regular transit service is not usually available. During Expo 2010 Shanghai in China, such shuttle services connected the major terminals and the expected locations of passenger generation. Because of constrained vehicle resources and the staggered characteristics of peak hours, the free time spans of regular vehicles were used to complete the fixed feeder timetables. An integer-linear programming model was developed to obtain the optimal schedules of the feeder vehicles, and an associated coordination mechanism was proposed to adjust the model-developed schedules to obtain feasible solutions. This model was applied to the feeder system in Jiading district during Expo 2010 Shanghai. The results showed that the temporary feeder system could serve Expo passengers with a relatively high level of service without causing evident degradation in the regular bus service.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2216-18
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2011
    detail.hit.zdb_id: 2403378-9
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  • 7
    Online Resource
    Online Resource
    Fatigue Assessment of Traffic Signal Mast Arms Based on Field Test Data Under Natural Wind Gusts
    SAGE Publications ; 2001
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1770, No. 1 ( 2001-01), p. 188-194
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1770, No. 1 ( 2001-01), p. 188-194
    Abstract: In recent years, several states including Missouri, Wyoming, California, and Texas experienced fracture failures of traffic signal mast arms. Almost all the failures are associated with the propagation of defects or cracks. It is therefore imperative to evaluate existing mast arms using a simple yet accurate procedure. A statistical methodology is proposed to predict the fatigue life of signal mast arm structures on the basis of field-measured strain data. The annual occurrence of various stress levels is determined using the historical wind speed data in the vicinity of a mast arm structure and the strain readings of the structure under specific wind gusts. For each stress level, the crack initiation and propagation lives are estimated with the strain-life approach and the Paris crack-growth-rate model. They are combined to account for variable stresses by means of Miner’s rule and the root-mean-square model, respectively. The stress concentration factor around the arm-post connection is determined using a finite element model. The parameters in the life prediction models are determined with ASTM flat tension and compact tension tests. The proposed methodology was applied to a 12.8-m (42-ft) long octagonal mast arm and a 16.5-m (54-ft) long circular mast arm in Missouri. It is concluded that signal structures in perfect condition will not crack under natural wind gusts during their service life. However, the 16.5-m-long arm is likely to be vulnerable to tiny defects around the weld connection, but the 12.8-m-long arm is safe unless a visible crack exists.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/1770-24
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2001
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  • 8
    Online Resource
    Online Resource
    Comparison of Ballast Drainage Improvement Between Track Lifting and Shoulder Cleaning Based on CFD Simulations
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 1 ( 2023-01), p. 201-211
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 1 ( 2023-01), p. 201-211
    Abstract: Railroad track performance largely depends on ballast drainage conditions. Over the years, different ballast maintenance methods have been developed and applied in the field, aiming to restore ballast drainage capability. But the benefits from different maintenance methods have not been well quantified and compared. This study investigates and compares the benefits of the two popular ballast drainage maintenance methods used in North America, shoulder cleaning and track lifting, through numerical simulations based on computational fluid dynamics (CFD). Different fouling conditions are simulated with permeabilities quantified from the field-collected fouled ballast samples to ensure that the numerical models are representative. Because the unit cost of shoulder cleaning and track lifting varies and depends on the specific application conditions, the normalized drainage health index (NDHI) and the normalized drainage restoration ratio (NDRR) are introduced to make fair comparisons and provide unbiased parameters for practitioners to use in the future. Preliminary results from this study indicate shoulder cleaning provides better ballast drainage improvement than track lifting if the unit costs per ballast volume of shoulder cleaning and track lifting are identical.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981221098659
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 9
    Online Resource
    Online Resource
    Capacity Modeling of Weaving Areas on Urban Expressways with Exclusive Bus Lanes Based on Gap Acceptance Theory
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 8 ( 2019-08), p. 365-376
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 8 ( 2019-08), p. 365-376
    Abstract: Intense lane-changing maneuvers at weaving sections often cause traffic turbulence on expressways, especially in the presence of a concurrent medium exclusive bus lane (XBL) and general purpose lanes. Such intense lane-changing activity usually affects the operation and reduces the capacity of weaving sections in relation to their equivalent basic expressway segments. In this context, a study on the capacity model of weaving areas on an expressway with a median XBL is conducted based on the analysis of lane-change behaviors using gap acceptance theory. Two weaving sections on expressways with median XBL are selected as case studies to obtain the estimated capacity as well as the maximum traffic throughput under a certain bus saturation on the XBL. The results show that estimated capacity is larger than maximum traffic throughput because of low utilization rate of buses on the XBL, and capacity is significantly affected by weaving demand. Error measures based on the estimated and observed maximum traffic throughput are analyzed to verify the validity of the proposed model. A sensitivity analysis shows that, compared with the increase of on-ramp bus flow ratio, the increase of off-ramp bus flow ratio results in a more obvious trend of the reduction of capacity and maximum traffic throughput.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119843235
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
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  • 10
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    Online Resource
    Hybrid Approach Combining Modified Gravity Model and Deep Learning for Short-Term Forecasting of Metro Transit Passenger Flows
    SAGE Publications ; 2021
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2675, No. 1 ( 2021-01), p. 25-38
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2675, No. 1 ( 2021-01), p. 25-38
    Abstract: Short-term forecasting of metro transit passenger flows is of great importance to the urban subway system in the various aspects of train and crew scheduling, congestion mitigation strategies, operational decision-making, and dynamic information provision. In this paper, a hybrid short-term forecasting approach is developed by combining the modified gravity model and deep learning models (e.g., convolutional neural networks [CNN] with auto-encoder). There are three components in this hybrid forecasting approach: (a) the modified gravity model that incorporates both the geographic information surrounding metro stations and station-level inflows/outflows as regression attributes; (b) the convolutional auto-encoder that tackles the sparsity issues of origin–destination (OD) matrices of passenger flows; and (c) the fusion of physical regression results and the decoder matrix, where the backpropagation algorithm is applied to tune the optimal fusion weight parameter matrix. The combination enables the proposed approach to achieve the trade-off between model interpretability and forecasting accuracy. The proposed approach is applied to the short-term forecasting of passenger flows for the metro transit network in Beijing, China. The experimental results show that the hybrid approach is promising and outperforms the benchmark models, for example, time-series models, long short-term memory, and CNN. The application demonstrates that the proposed hybrid short-term forecasting approach is suitable in both the station-level trip generation/attraction and the inter-station OD passenger flows.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120968823
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
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