With length in miles, calculate travel time in minutes. Select the minutes field, type [Length_Mi] * (60/ [SPEED_MPH]) in the formula box, and click OK. 6. Create a query that shows only streets where Type = ‘FRWY' or Type = ‘RAMP'. Use the Field Calculator to populate the OneWay field for each selected record with the value FT (a code for From-To). Because directionality has been carefully managed for this data, these codes can be applied for all the limited access dataset. 7. Assign an FT code to five specific Redlands city streets by creating a query where "TYPE" = ‘ST' AND "NAME" = ‘STATE' AND "PREFIX_DIR" = ‘E' AND "LEFT_ FROM_" <500. Use Field Calculator again to place an FT code in the OneWay field for these five records. Redlands streets are now ready to be used for building a time-based network. Zoom to the data extent, save the map document, and admire the project. The tasks in this exercise might seem a bit rigorous, but these steps were necessary to create a quality network source without compromising the data. Save this enhanced dataset for future activities. Summary In previous exercises, the ArcGIS Network Analyst extension was used to model time and distance response from fixed facilities. Experiment with this network street dataset by creating a network dataset from it and using it to work the Routes and Service Areas exercises in previous ArcUser articles in this series, noted at the beginning of this article. Acknowledgments Thanks go to Tom Patterson, Esri public safety specialist, for requesting this exercise and obtaining the Redlands data. Special thanks also go to the Redlands GIS staff members for providing this excellent dataset and allowing me to prepare and use it for this exercise. Create a query that shows only streets where Type = ‘FRWY' or Type = ‘RAMP' and use the Field Calculator to populate the OneWay field with the FT (From-To) code for each selected record. 1. Make Streets with Speed and Direction nonvisible, set transparency at 0 for Streets with Speed, and make Streets with Speed the only selectable layer. This layer displays all records in streets_nw. 2. Open its attribute table, locate the Length_ Mi field, and click on its field header. 3. Select Calculate Geometry and specify Property: Length. Use the coordinate system for the data frame and specify units as Miles U.S. Click OK to calculate all segments. 4. With length in miles, travel time in minutes can now be calculated. Open the Field Calculator. Select the MINUTES field and type [Length_Mi] * (60/ [SPEED_MPH]) in the formula box. Click OK and check the calculations. 5. Now, assign a OneWay code to all limitedaccess streets. Close the Streets with Speed attribute table and open the Streets with Speed and Direction attribute table. This layer also references the streets_nw shapefile, filtered to show only limitedaccess streets and a subset of Redlands streets. www.esri.com ArcUser