Additional key definitions
are provided below:
- Market Sector - A market sector is generally defined
by a common set of input trip tables that define the zone-to-zone
travel demand characteristics. Market sectors within an
alternative will typically define the different modes of
transportation available for analysis; they may also be
used for defining different trip purposes, times of travel,
or other variables.
- Network - A network refers to the collection of
zones, links, and link attributes that represent the transportation
system infrastructure.
- Graphical User Interface (GUI) - The GUI refers
to the graphical screen displays, dialogs, and user input
fields that comprise the model user interface on the computer
screen. The GUI allows the model user to navigate between
the different modules; input required data fields; view
and edit data attributes; run analyses; and save results.
The GUI is the Windows-based environment in which the IDAS
user views and operates the model.
- Database - The IDAS database serves as the repository
of the data read into the model as well as outputs from
the analysis procedures. Unlike many traditional travel
demand models, the IDAS model does not create individual
output data files during different phases of the analysis
to be passed on to the next analysis phase. Instead, data
are stored in various fields of the IDAS database. The different
modules access these data directly from the database, perform
the required data manipulations, and pass the results back
into the database. These data may be viewed by the user
through screens provided by the GUI. For some data, the
input/output interface can be used to create files for subsequent
input to travel demand models.
- ITS Benefits Library - The ITS Benefits Library
is a separate file that contains data on the range of impacts
associated with the deployment of individual ITS components.
The data in the library were compiled from numerous evaluations
of observed and simulated impacts of ITS deployments. Benefits
are segmented into different categories including: travel
speed; throughput; mode shifts; accident impacts; emission
impacts; agency efficiency impacts; and cost impacts, among
others. The database was used to guide the default values
used in the different IDAS analysis modules. The IDAS user
is able to view the data contained in the ITS
Benefits Library as part of the model user help option.
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