Correct Answer - Option 3 : General Motors’ model
Concept:
General Motors' model:
It is the most popular of the car-following theories because of the following reasons:
1. Agreement with field data: The simulation models developed based on General motors' car following models show good correlation to the field data.
2. Mathematical relation to macroscopic model: Greenberg’s logarithmic model for the speed-density relationship can be derived from General motors' car-following model.
Additional Information:
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.
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”.
- 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.
Optimal velocity model:
- The concept of this model is that each driver tries to achieve an optimal velocity based on the distance to the preceding vehicle and the speed difference between the vehicles.