A method is provided that permits users to create a “template” set of network elements with a unique set of parameters and setting preferences. This is done by specifying a name for a template TFX database file that utilizes the desired preferences. This is controlled by the “Check Default Database On Open” control in the File…Preferences dialog box. A “Default Database” field and Browse button is provided to specify the designated default database path and file name. The Santa Clara County (California) VTA has utilized this feature to insure that the municipalities in its jurisdiction utilize TRAFFIX in a consistent manner. Their default.tfx database is set to use the 1985 HCM methodology with modified saturation flow rates and a predefined set of minimum green times to accommodate pedestrian movements.
The default database should have one network item for each type of network element, i.e., a signalized intersection, an unsignalized intersection, etc.. If more than one of a given network item is present, the network item with the lowest identification index will be used as the default for each type of drawing tool. For links, gates, zones, and text fields, this is index number 1. For intersections, this is the lowest numerical index for each type of intersection (because all intersections are numbered sequentially, regardless of type). Only new items added to the network with the drawing tools will have the “user default” values. Any network items already in the database will retain the settings they already have.
With the Preference settings entered and activated, the default database will be automatically loaded and minimized. Any database which is subsequently opened will be compared to the default database and if the default data is different, the user will be given the option to update the settings to match those of the default database.
Figure 30 Default Database “Loaded” in Preference Dialog Box
If the “Check Default Database Data On Open” flag is not turned on, the database will not be checked when it is loaded. This would allow a database with different default data than in the default database to be loaded without the user being prompted to update the default data. Ordinarily, this flag should always be turned on if a default database is being used. If a default file name is not entered and the check box is turned on, the default settings become those of the TRAFFIX program. Ordinarily, a default database name should be used if the check box is turned on.
This process does not permanently change the new database’s internal default values. The usual default values are still stored within each individual database, and User Default values do not take effect until an open database has been updated with the default values from the User Default Database specified in the Preferences dialog box. This is only done when a database is opened while the “Check Default Database Data On Open” flag is turned on, or when the default database is saved.
Figure 31 Default Database Illustration