VISSIM 5.30-05 User Manual

Parameters of the Social Force Model in VISSIM
apparently not oriented into a particular direction as soon as an area
behind the channel is their next (intermediate) destination area. In this
case, the value of the parameter can be reduced to 0.1 m. This change
increases the memory requirements and further reductions might cause
further problems. Therefore, each project should use the default value
until reductions are required for trouble shooting purposes.
► Use_cache
The pedestrians calculate their desired direction (the direction of the
desired velocity) as the gradient of a look-up table (physicists also call it
"potential") of distances toward the destination area. Since obstacles are
considered in the calculation of this look-up table this calculation is very
complex and usually takes some time. To reduce the required time, the
look-up table can be saved to disc by setting use_cache=1; thus, if you
re-run the simulation without changes to the geometry, the look-up table
will be read from disc instead of being calculated anew.
Known bug: From time to time it might happen that VISSIM does not
realize that the geometry has changed. In this case, a wrong potential
will be read from disc and pedestrians might walk strangely. To solve this
problem, set use_cache=0, run the simulation once, and set it back to
use_cache=1, if applicable.
User Manual © PTV AG 2011 433