Traffic Parameters Research Paper

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Traffic Parameters In order to understand traffic behavior, a thorough knowledge of traffic parameters is required. The traffic stream is based on driver as well as vehicle behavior. As the human behavior is not constant, traffic stream is also heterogeneous in nature. It depends upon the distinct characteristics of vehicle and driver as well as the way a group of such driver-vehicle unit interacts with each other. Therefore, the traffic stream performance is based upon many different parameters through which its characteristic can be predicted. These are called the traffic parameters. The traffic parameters can be mainly classified as: Speed Flow Density These traffic parameters are characterized as macroscopic when the traffic is analyzed…show more content…
flow, density, and speed, while the microscopic parameters include the separation between the vehicles, for e.g. time headway or space headway. 2.1.1. Speed Speed is considered as a quality measure of travel because the drivers and passengers are concerned more about the speed of the journey than the design aspects of the traffic. It is defined as the distance covered per unit time. Speed can be expressed in a number of different ways, like, spot speed, running speed, time mean speed and space mean speed. Some of these are discussed below. Spot Speed Spot speed is the instantaneous speed of a vehicle at a particular location. It is used to design the geometry of the curves on road, the location of signs and signals and for determining the speed zone. Running speed Running speed is the average speed of vehicle which is maintained over a stretch of road while the vehicle is moving where there is no obstruction in the way of vehicle. It is measured by dividing the road stretch on which vehicle was moving by the time during which vehicle was moving. 2.1.2.…show more content…
Following In order to account for inexact handling of the throttle, when a vehicle passes into the following regime, vehicles acceleration rate is assumed to be always according to the leading vehicle. Free driving The vehicle in this regime is located above all thresholds in the phase diagram and travels uninfluenced of the surrounding traffic. The vehicle uses its maximum acceleration to reach its desired speed. Approaching In this situation, the driver notices that he or she is approaching a slower vehicle, he decelerates in order to avoid collisions. Danger regime (braking) When the front of following vehicle to rear of leading vehicle distance is very small, the follower adopts emergency deceleration to avoid collision with the vehicle in front. Drivers react to changes in spacing or relative speed only when these thresholds are crossed. The thresholds are usually presented in the relative speed/spacing diagram for a pair of leading and following vehicle. Figure 2.1 shows the difference of velocity (∆v) with the increase in the distance between the vehicles (∆x), in each of the four situations. Different thresholds are shown with different shapes according to their

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