The speeds of the leading vehicle following vehicle

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Unformatted text preview: cles start looking for the availability of the space between two consecutive vehicles on the next lane when they see the closed lane traffic sign. From that point vehicles compute the distance available between two consecutive vehicles on the next lane. The vehicles maintain their traveling lane until they find available lane changing space on the next lane. If there is no available space for lane changing, the vehicles travel on their lane until the lane ends, and they stop at the end of the lane. They wait until they find available space for lane changing. 70 Other type of lane changing is the discretionary lane changing behavior. Discretionary lane changing occurs when passing over a low speed vehicle or when yielding another merging vehicle. When there is an available space for lane changing, the vehicle which will change the lane checks the speed of the leading vehicle on the other lane. If the speed of the leading vehicle is greater than the lane changing vehicle, the lane changing vehicle accelerates during merging and after it changes the lane it adjusts its speed according to the car following behavior. If the speed of the leading vehicle is less than the lane changing vehicle, it decelerates until it reaches the speed of the leading vehicle during merging. After it completes merging, it adjusts its speed according to the car following behavior. Discretionary lane changing behavior is not included in this simulation model. Vehicles in the construction zone simulation example model only have the mandatory lane changing behavior. Lane changing distances are dependent on the gap acceptance of the drivers. The literature showed that the speeds of the vehicles determine the car following distances of the drivers and the lane changing distances are determined according to these car following distances. In addition to the speed of the vehicles, the relative speed of the vehicles on different lanes affect the distance required for lane changing. Using the derived lane changing distances from Kanaris et al. [32] and Rakha and Crowther [33], the required lane changing space for the traffic simulation model was derived. If the speed of the merging vehicle is greater than or equal to the speeds of the leading and following vehicles on the other lane the values given in Table 18 are used for lane 71 changing space. If the speed of the merging vehicle is less than the leading and the following vehicles on the other lane the values given in Table 19 are used for lane changing. Table 18: Required Space for Lane Changing when the Merging Vehicle Speed is Greater or equal than the Desired Lane Speed Required Gaps for Lane Changing (ft) Speed Passenger Car Truck Lead Gap Vehicle Length Lag Gap Total Vehicle Length Total Speed <= 10 ft/s 40 ft 20 ft 5 ft 65 ft 65 ft 110 ft 10 ft/s <Speed <= 35 ft/s 65 ft 20 ft 10 ft 95 ft 65 ft 140 ft 35 ft/s <Speed <= 55 ft/s 100 ft 20 ft 20 ft 140 ft 65 ft 185 ft 55 ft/s <Speed <= 75 ft/s 130 ft 20 ft 20 ft 170 ft 65 ft 215 ft 75 ft/s < Speed 165 ft 20 ft 30 ft 215 ft 65 ft 260 ft 72 Table 19: Required Space for Lane Changing when the Merging Vehicle Speed is less than the Desired Lane Speed Required Gaps for Lane Changing (ft) Speed Passenger Car Truck Lead Gap Vehicle Length Lag Gap Total Vehicle Length Total Speed <= 10 ft/s 5 ft 20 ft 40 ft 65 ft 65 ft 110 ft 10 ft/s <Speed <= 35 ft/s 10 ft 20 ft 65 ft 95 ft 65 ft 140 ft 35 ft/s <Speed <= 55 ft/s 20 ft 20 ft 100 ft 140 ft 65 ft 185 ft 55 ft/s <Speed <= 75 ft/s 20 ft 20 ft 130 ft 170 ft 65 ft 215 ft 75 ft/s < Speed 30 ft 20 ft 165 ft 215 ft 65 ft 260 ft Another important decision in determining the required space for the lane changing is the stopped traffic conditions. When the vehicles traveling on the lane which will be closed, could not find enough space, they stop at the ane closure taper. The l number of vehicles waiting in the queue for lane changing affects the drivers’ gap acceptance behavior. When there are vehicles waiting in the queue, drivers are more likely to change their lanes even if there is smaller space available on the other lane. It was assumed that the merging at the stopped traffic conditions occurs in a first come first serve basis. The vehicle at the beginning of the queue merges first all the time. In Table 20 minimum space used in the simulation model for lane changing when there are less than 3 vehicles waiting in the queue are given. The minimum space was calculated with the assumption that when there are vehicles waiting in the queue they are 73 willing to change lanes with smaller gaps, which is less than their travel distance in one second, when there are no vehicles waiting. In Table 21 required space for lane changing when there are less than 5 but more than 3 vehicles waiting in the queue are given. In Table 22 required space for lane changing when there are less than 10 but more than 5 vehicles waiting in the queue are given. In Table 23 required space for lane...
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This document was uploaded on 02/26/2014 for the course E 515 at University of Louisiana at Lafayette.

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