Node impedance of nodes VD function

In this model, turn delays are calculated in two steps. First, a node delay is calculated by applying a VD function to the vol/cap ratio of the node. Each turn penalty is the sum of node delay and the turn-specific time (calculated with VD function set for turns). Node delay only has an affect on turns from a non-prioritized approach. These approach links have to be marked with the attribute TModelSpecial (Using Visum: Junction editor and signal control).

The attributes listed in Table 98 are considered for the calculation.

Table 98: Attributes for impedance calculation based on node 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 turning direction
Node	Capacity PrT	The total capacity of the node in PCUs/hour
Node	t0 PrT	The additional time required for a non-prioritized turning movement (all the same) in unloaded state

Turn time penalties are calculated according to the following formulas:

Vol(k) = ∑Vol(a)

delay(n) = VDF (cap(n), vol(n))

delay(t) = VDF (cap(t), vol(t))

IF n has no link with TModelSpecial = 1, THEN

tCur(t) = delay(t) + delay(n) for all turns t via node n

IF n has at least one link with TModelSpecial = 1, THEN

tCur(a) = delay(t) for all turns t with a 'from link' to which TModelSpecial = 0 applies

tCur(a) = delay(t) + delay(n) for all turns t with a 'from link' to which TModelSpecial = 1 applies