One method for relating Roads and Trails files with lookup tables in ArcView

1- First, go through the steps to import the DLG data into ArcView and convert it to a Shapefile. Then you can go through the steps listed below. This is certainly not the only way to use the lookup tables, but it does work fairly well.

2- Open the table and from the Table dropdown menu select 'start editing'. Then go to the Edit menu and select add field. You need to add three fields: mm1, a number field, with 16 places; then mm2 and mm3 defined the same way.

3- Once the fields are created, select mm1 in the table, go to the Field menu, and chose calculate. Double click on "major1", "+", "minor1", and then okay. Do the same for mm2 and mm3, using major2, minor2, etc. Once this is done, go to the Table menu and chose stop editing. Save the changes when prompted. Close the table.

4- Select the view related to the table you wish to work with. Make the Shapefile active, and then open the attribute table for that Shapefile using the View dropdown menu (do NOT go to tables and open it there - the joins are harder to do and may not work properly). You will need to do three joins; one each for mm1, mm2, and mm3. You can join all three to the same columns in the lookup table (100trrd.dbf, field mm1), as the field definitions and values are the same. You may want to create alias names for the description fields (for example mm1desc), to make it easier to identify the data.

5- Once the joins are done, create a new column called totdescript (similar steps to #2). Select the column and calculate the values as in #3, but use "mm1desc", "++", "mm2desc", "++", "mm3desc" as the values to create the field. In most cases there will only be a value in one of the description fields, so you will only end up with one value in the totdescript field.

6- Remove all the joins.

7- It is likely that any totdescript items where major1 is coded 172-176 will need to be recalculated. To do this rapidly, go to the Table menu, choose query, major1=174 (or any other code), and create a new set. Then with the new set still selected, do query, minor1 =, and double click on one of the values listed. For each value you will need to create a new set, do a specific calculation for totdescript (for example fill in U.S. Route 3), and then clear the selected records and start again. For the sample data there were only 2 or 3 edits needed - this did not take long. It is likely that all of the values listed for minor1 are not valid for the editing you need to do - this has to do with the multiple major and minor codes and values. You can verify which values you need to edit by looking at the items selected with the major codes.

Note on other transportation files Relates on the other two types of transportation files were done on the minor1 codes, and worked well that way.

For additional information regarding this Web page, contact Deb Southworth Green, in the Division of Information Resources and Technology Management, at Deb_Green@fws.gov

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Keywords=GIS, data,data conversion, tools, DLG, Transportation
Last Modified January 03, 2001 06:49 AM