Junction modeling

Visum provides the possibility to model junctions in detail. There are two major fields of application, namely the use of a detailed node impedance model among others in assignment procedures, and the export for a micro-simulation in Vissim.

Table 11: Network objects of the junction model
Element	Description
Geometry	Geometries are used to describe the geometry of nodes and main nodes in detail. The principal elements of geometries are legs.
Leg	A leg geometry consists of a set of legs. A leg describes an entry to the node section and the corresponding exit. A set of legs at a node or main node is defined by the set of link orientations.
Lanes	A leg consists of a set of incoming and outgoing lanes. Through lanes are the ones that lead right up to the adjacent node and pocket lanes start and end at a certain distance from the node area.
Lane turns	Lane turns define a relation between an incoming lane and an outgoing lane. They are used for detailed transport system and lane-based descriptions of the turn conditions at a node.
Signal controller	A signal controller describes the total of all signal control data at one or more nodes or main nodes. There are signal controllers of the type Vissig that can contain both stage-based and signal group-based signal programs, and there are RBC type signal controllers.
Stage	A stage is the basic unit of a signal plan in case of stage-based signal controllers. A set of signal groups is allocated to each stage. The green times of the signal groups result from the sequence of stages and the interstages.
Signal group	A signal controller contains a set of signal groups, even if it is stage-based. Signal groups are used to describe the signalization in detail, with a lane turn-based approach.
Crosswalk	Crosswalks serve to describe the pedestrian conditions at nodes and main nodes. They refer to legs. A leg can have several crosswalks depending on whether a center island or a channelized island has been defined.
Detector	A detector is allocated to a node or a main node. This type of detector serves for modeling the signalization, for example, traffic-responsive signal control.