Using lateral drift speed

You can define functions for later drift speed. They allow you to determine the lateral drift speed of the vehicle for the speed quotient, which is calculated using the Critical Speed function. Vissim uses the Lateral drift speed function to calculate the lateral offset Lateral deviation (excessive speed) for vehicles that change their lateral position due to excessive speed. A vehicle whose Radius attribute corresponds to the Radius of curvature value x is carried out of a curve at a 3D point or drifts sideways.

In the Vehicles in the network list, you can display the Lateral deviation (excessive speed) of the vehicle (Displaying vehicles in the network in a list).

1.  On the Base Data menu, click > Functions > Lateral drift speed.

The list of defined objects for the base data type opens.

By default, you can edit the list (Using lists).

2.  In the list on left, on the toolbar, click the Add button .

3.  In the Name table field, enter a name for the function.

4.  Repeat the following steps for the desired number of data points.

5.  In the list on right, on the toolbar, click the Add button .

6.  Enter the desired data.

Element	Description
x	Speed quotient: Current vehicle speed / critical speed in Critical speed function (Defining critical speed). Threshold value from which lateral drift speed y is used to calculate the lateral offset. Default value 1.0.
y	Lateral drift speed: Speed [m/s] used for speed quotient x at which the vehicle changes its lateral position. The function value is linearly interpolated between several interpolation points.

You assign the function as an attribute to those vehicle types you wish to impact (Attributes of vehicle types).