Node impedances of turns VD function

In the simplest calculation model tCur, the time requirement of a turning vehicle is calculated from the turning time t0 in the unloaded network and the saturation of turns using a VD function. You can use one of the pre-defined functional forms (Predefined VD functions) as VD functions or select a user-defined functional form (User-defined VD functions). Typical Turn VD functions make up the sum (not the product) of t0 and a saturation-dependent term. Examples are the VD functions Akcelik, Exponential, Constant, Logistic, Quadratic and TMODEL_Nodes.

The attributes listed in Table 97 are considered for the calculation.

Table 97: Attributes for impedance calculation based on turns VD function

Network object	Attribute	Description / Effect
Turn	Capacity PrT	The capacity of the turn in PCUs/hour
Turn	t0 PrT	The time required for a turning movement in unloaded state
Turn	Type	Usually specifies the direction of the turn