VISSIM 5.30-05 User Manual

Building an Abstract Network
When modeling parking lots at the borders of a network, a
single node on the border can be used for correctly placing both
the origin and the destination parking lot (see illustration).
Parking lots must be placed on an edge between two nodes. They may
also be placed inside of an internal node (a node that is not situated at the
border of the network).
No more than one parking lot must be placed between any two nodes or
within a node.
A parking lot blocks the road in terms of path search: There are no paths
that include a link that leads through a parking lot (i.e. where the parking lot
would be ignored).
If a parking lot (for destination traffic only) is placed on an outgoing link of
the network, i.e. a link from which no other parking lots can be reached,
then the relative flow of the parking lot must be set to zero. Make sure that
there is at least one node on both sides of the parking lot.
The cost for each edge where a parking lot is placed on, is determined as
the average cost of all vehicles traveling into and out of the parking lot.
CTRL+SHIFT+C sets the relative volumes of all parking lots to the volume
totals of their paths as contained in the current path file (*.WEG). This can
be helpful, if a new volume scenario (new matrix and path file) is to be
applied to a network which was originally exported from VISUM, since
relative volumes of origin parking lots might fit significantly better this way.
Potential traps
If you get an error message similar to "The destination parking lot 10 is part
of several different edges", typically at least one node is missing or placed
incorrectly. That results in multiple paths being found between the two nodes
where the parking lot is placed, and for each path a separate cost is
evaluated. On rare occasions, this could result in multiple different link costs
for the same stretch of physical road and thus would lead to a wrong
distribution of vehicles.
To solve this problem, locate that parking lot in the VISSIM network and
ensure, that
► both, the path diverge point before the parking lot as well as the path
merge point after the parking lot (in direction of driving) are included in a
node and
► both the nodes, where the parking lot is placed in between, are modeled
correctly in terms of including the path diverge/merging point
User Manual © PTV AG 2011 599