gipps Class Reference

Gipps car-following model (1981). More...

#include <gipps.h>

Inheritance diagram for gipps:

Public Member Functions
	gipps ()
	Default constructor for the Gipps model.
	gipps (p_gipps *p)
	Constructor with custom parameters for the Gipps model.
void	validate_parameters (params *p=(params *) nullptr) override
	Validates the parameters of the Gipps model.
double	equil_spcg (double vl, double vf, params *p=(params *) nullptr) override
	Computes the equilibrium spacing between vehicles according to the Gipps model.
double	wave_speed (point *leader, point *follower, params *p) override
	Not implemented yet.
double	free_flow_speed (params *p=(params *) nullptr) override
	Computes the free-flow speed for the Gipps model.
point *	new_point (generalized_trajectory *leader, trajectory *follower, params *p=(params *) nullptr)
	Computes the next point in the follower's trajectory based on the leader's movement.
Public Member Functions inherited from model
virtual point *	new_point (point *leader, point *follower, params *p=nullptr)
	Compute the next point for a vehicle.

Additional Inherited Members
Public Attributes inherited from model
params *	pars
	Parameters for the car-following model.
Protected Member Functions inherited from model

Detailed Description

Gipps car-following model (1981).

This class implements the Gipps (1981) car-following model, which aims to simulate the behavior of vehicles in a traffic stream, particularly how a vehicle responds to the movement of the preceding vehicle. The model is based on realistic driver and vehicle behavior constraints such as maximum acceleration, braking, and desired speeds.

The model introduces two main constraints:

• A free acceleration component that limits acceleration as the vehicle approaches its desired speed.
• A braking component that ensures the vehicle can safely stop if the vehicle ahead brakes suddenly.

Reference: Gipps, P.G. (1981), "A Behavioural Car-Following Model for Computer Simulation", Transport Research Part B, Vol. 15, pp. 105-111.

Constructor & Destructor Documentation

gipps() [1/2]

gipps::gipps

(

)

Default constructor for the Gipps model.

Initializes the model with default parameter values, including default values for maximum acceleration, braking, and reaction time.

gipps() [2/2]

gipps::gipps

(

p_gipps *

p

)

Constructor with custom parameters for the Gipps model.

Initializes the model with a custom set of parameters, allowing the simulation to represent different vehicle and driver behaviors.

Parameters

p	A pointer to a p_gipps parameter class containing the custom parameters.

Member Function Documentation

equil_spcg()

double gipps::equil_spcg ( double vl, double vf, params * p = (params *) nullptr )

overridevirtual

Computes the equilibrium spacing between vehicles according to the Gipps model.

The equilibrium spacing is the safe distance that vehicles should maintain, accounting for the vehicle's speed and the driver's braking limits.

Parameters

vl	The velocity of the leader vehicle.
vf	The velocity of the follower vehicle.
p	Parameters for the Gipps model. If null, the model uses its default parameters.

Returns

The equilibrium spacing between the vehicles.

Implements model.

free_flow_speed()

double gipps::free_flow_speed ( params * p = (params *) nullptr )

overridevirtual

Computes the free-flow speed for the Gipps model.

The free-flow speed represents the maximum speed the vehicle can travel at, assuming there is no interaction with other vehicles ahead (i.e., no leader).

Parameters

p	Parameters for the Gipps model. If null, the model uses its default parameters.

Returns

The free-flow speed of the vehicle.

Implements model.

new_point()

point * gipps::new_point ( generalized_trajectory * leader, trajectory * follower, params * p = (params *) nullptr )

virtual

Computes the next point in the follower's trajectory based on the leader's movement.

This function computes the next position, speed, and acceleration of the follower vehicle based on the current position of both the leader and follower vehicles. The model applies both acceleration and braking constraints to ensure safe car-following behavior.

Parameters

leader	Generalized trajectory of the leader vehicle.
follower	Trajectory of the follower vehicle.
p	Parameters for the Gipps model. If null, the model uses its default parameters.

Returns

A new point representing the updated position, speed, and acceleration of the follower.

Reimplemented from model.

validate_parameters()

void gipps::validate_parameters ( params * p = (params *) nullptr )

overridevirtual

Validates the parameters of the Gipps model.

Ensures that the parameters for maximum acceleration, braking, and reaction time are non-zero and valid. If invalid, an exception is thrown.

Parameters

p	Parameters for the Gipps model. If null, the model uses its default parameters.

Reimplemented from model.

wave_speed()

double gipps::wave_speed ( point * leader, point * follower, params * p )

overridevirtual

Not implemented yet.

This function is a placeholder for the wave speed calculation. In the Gipps model, the wave speed is not explicitly calculated.

Parameters

leader	A point representing the leader's position and speed.
follower	A point representing the follower's position and speed.
p	Parameters for the Gipps model.

Returns

Always returns zero (0.0).

Implements model.

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The documentation for this class was generated from the following file:

• include/gipps.h