VISSIM 5.30-05 User Manual

12.4.2 Trip Chain Files
Traffic Demand
With Dynamic Assignment it is also possible to supply traffic demand of a
simulation with trip chains. In contrast to OD matrices a trip chain file allows
to supply the simulation with more detailed travel plans for individual
vehicles; however, the coding effort is much higher.
VISSIM internally works with trip chains only. If OD matrices are used, a preprocessing
algorithm generates trip chains from these matrices. Thus it is
possible to mix traffic demand by OD matrices and trip chains in the same
simulation.
To provide traffic demand with
trip chains, in the Dynamic
Assignment window check the
option associated with the button
TRIP CHAIN FILE. Then press TRIP
CHAIN FILE and select a single
file with the extension *.FKT.
A trip chain file contains a set of
individual-vehicle travel definitions
(trip chain), each one
composed of one or more trips.
A trip chain is associated with a vehicle and identified by three numbers:
► Vehicle number
► Vehicle type
► Origin zone number
After this “header” one or more trips follow. A trip is defined by a group of
numbers – four numbers in data format 1.1 or five numbers in data format
2.1:
► Departure time
► Destination zone number
► World coordinates of the destination (format version 2.1 only)
► Activity number
► Minimum stay time
The departure time of the next trip depends on the arrival time in that zone
and on the minimum stay period for this activity. The specified departure time
for the next trip will be taken in account only if the minimum stay time is
guaranteed: If a vehicle arrives too late the departure time is corrected to the
sum of the actual arrival time plus the minimum stay time.
Trip chain file format (*.FKT)
The trip chain file (*.FKT) is line oriented, i.e. each line specifies a trip chain
(a sequence of trips for an individual vehicle). The actual trips of a trip chain
are formatted as groups of columns separated by semicolon:
► The first three columns specify the vehicle number and type and its origin
zone.
User Manual © PTV AG 2011 617