Turn standards

Turn standards are templates which assign newly created turns with values for their attributes Turn time penalty (t0-PrT) and Capacity. Which turn standard is used to assign attributes of each turn, conforms to the three following criteria:

• type of node via which the turn runs
• type of turn (right, straight ahead, left)
• flow hierarchy which depends on the rank of a link entering a node

For each node, Visum evaluates the rank of the links involved and thus determines a major flow (Link types). This automatically determined major flow can be edited manually. The flow hierarchy describes whether a turn follows this major flow, from this one into a minor flow, from one minor flow into the major flow or leads from minor flow to minor flow. These four steps of the flow hierarchy are designated with the symbols from Table 5.

In combination with node types, turn types and flow hierarchy, you can assign the turns very differentiated turn times as standard. These turn times can then be considered within the assignment (Impedances at nodes). The Illustration 5 shows an example of turn standards.

* Attention: Time always in seconds

* Table: Turn standards

$TURNSTANDARD:ID;NODETYPE;TURNTYPE;FLOWHIERARCHY;T0PRT;CAPPRT

1;10;1;--;10s;32000

2;10;1;-+;10s;32000  // Right turn from minor flow into major flow

3;10;1;+-;10s;32000  // Right turn from major flow into minor flow

4;10;1;++;0s;32000   // Road with right of way which bends to the right

5;10;2;--;15s;32000  // Crossing from minor flow into minor flow

6;10;2;-+;10s;32000

7;10;2;+-;10s;32000

8;10;2;++;0s;32000   // Crossing straight from major into major flow

9;10;3;--;20s;32000

10;10;3;-+;20s;32000 // Left turn from minor flow into major flow

11;10;3;+-;15s;32000 // Left turn from major flow into minor flow

12;10;3;++;0s;32000

Illustration 5: Example of a TURNSTANDARD table in the network file, which is used to specify default values for turn penalties and turn capacity