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Spatial Models Using Partial Differential Equations
Published in Sandip Banerjee, Mathematical Modeling, 2021
Traffic flow is defined as the total number of vehicles passing a given point in a given time and is expressed as vehicle per hour. It is the investigation of the interaction between vehicles, drivers, and infrastructure, which aims to understand and build an optimal road network with efficient traffic movement and minimal traffic congestion. The efficiency of the traffic flows depends on three basic characteristics, (i) flow (the number of vehicles passing a point in a given time period), (ii) velocity (vehicle's rate of motion in a particular direction) and, (iii) density (the number of vehicles occupying a unit length of the roadway at an instant in time).
Traffic and Transportation Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Traffic flow is the investigation of the movement of individual drivers and vehicles between two points and the connections they make with each other. Shockingly, contemplating traffic stream is troublesome in light of the fact that driver conduct is something that cannot be anticipated with 100% assurance. To more readily represent traffic stream, relationships have been built up between the three main fundamental attributes: (1) stream, (2) density, and (3) velocity. These connections help in arranging, design, and activities of roadway facilities.
Effect of local roughness damage and traffic flow on bridge dynamic responses
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
At the same time, current traffic flow data are also monitored via two cameras set on two lanes of the bridge. The traffic flow condition is characterized by traffic volume, which is the number of vehicles passing through a specific section in a specific time interval. To simplify the vehicle variation, traffic types are classified only as car and truck. During the data acquisition period, the number of cars and trucks passing through the bridge are counted every 5 minutes. Six sets of both 5-minute acceleration data and traffic counting are collected. At both lanes of the bridge, the measured accelerations are only slightly different between two sensors. For all measurement sets, the recorded response data are almost the same at both sensors. The plots of traffic volume and RMS of vertical acceleration in 6 sets data at two lanes of the bridge are presented on Figures 2 and 3. It is seen that in the test-bed structure, the number of trucks are almost higher or equal to the number of cars, causing high bridge excitation responses. The measured traffic data and bridge responses will be used for creating the input force of traffic in time history analysis.
Application of area traffic control using the max-pressure algorithm
Published in Transportation Planning and Technology, 2020
S. A. Ramadhan, H. Y. Sutarto, G. S. Kuswana, E. Joelianto
With increasing personal mobility and the rapid growth in the number of vehicles, congestion has become a common occurrence. Traffic signal control is one of the key techniques for influencing the effectiveness of traffic flow in urban networks that enables conflicting traffic to flow through intersections using the timing of green/red light periods. Finding the best possible cycle time over many intersections to decrease congestion overall and to increase throughput by means of the network is challenging. In general, there are two types of control for signal control: static/fixed time control and vehicle-actuated control. The former comprises the optimization of the cycle time, offset and split of green times. This can be optimized in a coordinated or isolation way (Gartner, Little, and Gabbay 1975). In contrast, the later uses online measurements from detectors to optimize signal timings on a cycle-to-cycle basis in real-time. Some examples of this type of controller: SCOOT (Hunt et al. 1981), UTOPIA (Mauro and DiTaranto 1990) and RHODES (Mirchandani and Head 2001). SCATS (Lowrie 1982) is one of the examples of a combination of fixed time control and vehicle-actuated control. Each algorithm has its own advantages and disadvantages, so it cannot be determined which is the best control system.
Analysis of roadside air pollutant concentrations and potential health risk of exposure in Hanoi, Vietnam
Published in Journal of Environmental Science and Health, Part A, 2020
Van Tai Tang, Nguyen Thi Kim Oanh, Eldon R. Rene, Tran Ngoc Binh
The decrease in the traffic flow velocity inversely correlated with the measured gaseous pollutant concentrations at the roadside, i.e. SO2 (R2 = 0.578; p < 0.05), NO2 (R2 = 0.738; p < 0.05), CO (R2 = 0.689; p < 0.05) and NMVOC (R2 = 0.747; p < 0.05) (Figure 4). Similar with the case of PM reported above, the monitoring results suggested that the reduction in the traffic flow velocity, due to high vehicle density in the street, would increase the vehicular emissions of pollutants and subsequently their roadside levels. During traffic jams, these gaseous pollutants (SO2, NO2, CO and NMVOC) are emitted at higher rates (higher amount in g per km travelled) from the exhausts of MC, bus, car and other motor vehicles plying the street and from more vehicles in the street, thereby causing the build-up of pollutants at high levels at the roadside, especially during the period of calm wind conditions selected in this study.
Massively parallelizable approach for evaluating signalized arterial performance using probe-based data
Published in Journal of Intelligent Transportation Systems, 2023
Subhadipto Poddar, Pranamesh Chakraborty, Anuj Sharma, Skylar Knickerbocker, Neal Hawkins
Transportation agencies install traffic signals to optimize traffic flow, reduce crash frequency, and prioritize particular roadway user type or movement (Chandler et al., 2013). Federal Highway Administration (FHWA) states that the operation and performance of the 300,000 signals in the United States (US) are addressed predominantly on the basis of citizen complaints (FHWA, 2017). Recognizing that a complaint-driven process is inefficient, many transportation agencies have sought objective methods for identifying and prioritizing corridors that require signal re-timing or the implementation of advanced signal control systems.