VISSIM 5.30-05 User Manual

Simulation of Pedestrians: Preconditions & How to
After creation of a new pedestrian, a strategic route is fetched from the
routing decision according to the type (class respectively) of the pedestrian.
If there is more than one route, one route is chosen randomly according to
the ratios of the route distribution.
The strategic route consists of a sequence of numbers of pedestrian areas
and ramps. These are copied to the pedestrian’s data structures. From which
routing decision the route was taken is stored here as well to avoid fetching
several routes again and again on one and the same routing decision.
How a pedestrian walks along the strategic route
A pedestrian always walks towards his nextmost strategic routing point.
Whether he aims at the exact coordinates of the point or only at the area
where the strategic point is located in, depends on the external movement
DLL that is used.
Once reaching it (i.e. entering the area that contains the point or reaching the
point itself) the external movement DLL makes the pedestrian wait according
to the dwell time distribution defined at the area. What the pedestrian “does”
during this time is determined by the DLL.
If this was not the end of the pedestrian’s strategic route, he moves on
towards the next strategic point. If this was the end point of the strategic
route and if the area, where the pedestrian´s current position is located in,
contains a routing decision defining routes for this pedestrian (more
precisely: for the class, the pedestrian belongs to), the pedestrian will get a
new strategic route and will start moving on along that route. If there is no
strategic route, the pedestrian will be removed from the scene.
Between two subsequent strategic routing points there may be several
possibilities to walk “tactically” (pass-by obstacles left or right, use one of
several ramps to change to another level, etc).
Currently, VISSIM computes an internal routing graph consisting of the usersupplied
strategic points and of the bottoms and tops of all ramps.
Each vertex A of this graph is connected to each other vertex B as long as
they are located on the same “walking partition” – i.e. pedestrians can walk
from A to B without changing level and without “loosing walkable ground”
inbetween.
Based on this graph, the shortest path between either two strategic points of
a pedestrian’s strategic route is determined and used for the tactic
movement of the pedestrian.
How routing decisions are applied
If a pedestrian without route (immediately after creation or at the end of his
route) enters a walkable area for which a routing decision has been defined
including routes for the type of the pedestrian and if the pedestrian does not
already have his current strategic route from this decision, a new strategic
route will be chosen from the routes defined for the type of the pedestrian.
User Manual © PTV AG 2011 427