Spring 2018 Quiz 1 CVEN453V Traffic Engineering NAME 1 List

Spring 2018 Quiz 1: CVEN-453V Traffic Engineering NAME: 1. List three traffic signal warrants. 2. Name a macroscopic traffic model. 3. List the three main measures of traffic streams. 4. Where are car-following models mostly used? 5. What is the danger of not calibrating a car-following model?

Solution

Q1) traffic warrents:

1) peak hour: this warrent is based on Vehicular volume and delay on minor street

2) school crossing : this warrent based on number of school childrens and thair gaps

3) Pedestrian Volume : this is based of number of pedestrians and thair gaps it is simmilar to school crossing

Q2)

Pipe\'s model

The basic assumption of this model is ``A good rule for following another vehicle at a safe distance is to allow yourself at least the length of a car between your vehicle and the vehicle ahead for every ten miles per hour of speed at which you are traveling\" According to Pipe\'s car-following model, the minimum safe distance headway increases linearly with speed. A disadvantage of this model is that at low speeds, the minimum headways proposed by the theory are considerably less than the corresponding field measurements.

2)

Forbes\' model

In this model, the reaction time needed for the following vehicle to perceive the need to decelerate and apply the brakes is considered. That is, the time gap between the rear of the leader and the front of the follower should always be equal to or greater than the reaction time. Therefore, the minimum time headway is equal to the reaction time (minimum time gap) and the time required for the lead vehicle to traverse a distance equivalent to its length. A disadvantage of this model is that, similar to Pipe\'s model, there is a wide difference in the minimum distance headway at low and high speeds.

Q3)THREE main streem mesures are

1) speed: average speed is measured by sampling vehicles in a given area over a period of time

2) density:The maximum density achievable under free flow is k_c, while k_j is the maximum density achieved under congestion

3) flow: movement of vehicals in certain length at at given time is flow of a vehicals.

Q4) this is noting but microscopic modling only these techniques are used in

1) the models shows good correlation to the field data.

2) used in stability analysis also.

3) to maintain study state flow of cars