VISSIM 5.30-05 User Manual

7 Simulation of Pedestrians
In the folder ..\EXAMPLES\TRAINING\PEDESTRIANS\PARAMETER
DEMONSTRATION you can find training example models specifically
demonstrating the effect of this parameter.
► routing_large_grid
This parameter defines the topological grid-size; routing_large_grid x
routing_large_grid cells become one cell in the superordinate grid.
The required memory depends on this parameter, but the precision of the
calculation of distances to destination areas does not. There is no global
value that fits best in any case. For small-sized scenarios (in a building,
for example) with numerous small obstacles and numerous walkable
areas a low value (< 10) is recommended. For large areas and big
obstacles (e.g. simulation of a district not regarding the details) even 100
or more can be set. Since we expect the 64 bit edition of VISSIM to be
used mainly for large-scale projects, the default value is 7 for the 32 bit
edition and 20 for the 64 bit edition. As long as no memory problems
occur in a project this parameter value can be kept. Problems that might
occur can be solved by changes to this parameter without subsequent
disadvantages.
► routing_step
This is one parameter that governs the calculation of the potential. If it is
large, the potential is more precise, but its calculation needs more time.
Resonable values are 2, 3, 4 or 5.
► routing_accuracy
This is the second parameter that governs the calculation of the
potential. It can take values in [0.0 .. 1.0] and results in more precise
potentials, the greater it is.
► routing_obstacle_dist
During the calculation of the static potential (aka “distance potential field”,
“distance look-up table”), grid cells which are close to walls receive a sort
of “extra distance” atop of their true distance. By this, one can achieve
that more pedestrians decide to choose a wide corridor instead of a
narrow one, if there are two corridors from one and the same source to
one and the same destination with identical walking distance. Generally,
the pedestrians keep some distance toward walls. With this parameter
the distance is set to which nearby walls influence the potential field. This
parameter only has an effect on the calculation of the static potential. It is
not yet considered in the calculation of the dynamic potential.
In the folder ..\EXAMPLES\TRAINING\PEDESTRIANS\PARAMETER
DEMONSTRATION you can find training example models specifically
demonstrating the effect of this parameter.
► routing_cell_size
This parameter defines the distances of fixed data points to be set for the
calculation of distances to a destination area. The default value is 0.
15 [m]. This default should only be edited if the model included
passageways with a width of 50 cm or less since pedestrians will not
pass these channels during the simulation. Instead, they will stand still
432 VISSIM 5.30-05 © PTV AG 2011