Many of you have started using the TMODEL2 layer file option. Congratulations! In our consulting projects at TModel Corporation, we would not dream of creating or working on a model without these additional graphic layers. They are the easiest place to start a model and one of the best places to check the network connections, zone structure layout, and zone loading locations. Up to three graphic layers can be displayed in the Network Graphic Editor on screen and plotted. Displaying the model network over all of the streets in an area can be very useful for presentations to non-technical people.

The previous newsletter mentioned that we at TModel Corporation are offering the layer files for only $90 per county to those with TMODEL2 Maintenance or for $200 per county without. Remember that you can use layer files derived from other sources as well. TMODEL2 section 4.4.9 allows you to import files from CAD (.DXF) format, MapInfo (.MIF) format, ASCII format, or convert from Link and Node files. The graphic layers are limited to lines and polygons for minimization of data storage and maximum drawing speed. If the city or county has an AutoCad map of the area, this may be an ideal place to start your model.

Another article in this newsletter describes creating a zone boundary layer using links and nodes. We have used this feature to import the zone boundary overlay from a 4-county regional model and then have used it to check the coincidence of zone boundaries in our 390-zone one-county model. When we were concerned about the trip table distribution in the regional model, we used the land use viewer (2.7.8) to check and view the distributions. No, we did not need to code the entire 4-county model. First, we imported the zone boundary file that had been saved in MapInfo format, then we inserted a node in each of the zones that corresponded to the zone number. For an 850-zone model, this process required about 4 hours. Then we could check the distributions and trip ends to or from any of the regional model zones! The layer file feature made this not only possible, but productive and efficient.