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How To: Create evenly spaced lines perpendicular to a line feature

Summary

When working with linear features such as roads, rivers, or pipelines, it may be necessary to derive information from lines running perpendicular to the main feature. This article describes how to create evenly spaced lines perpendicular to a line feature.

Procedure

There is no geoprocessing tool that automatically performs this task. This procedure uses tools available with the Basic license of ArcGIS and uses the concepts of routes and route events to accomplish the task.

  1. From the main line feature (pipeline, river, road, etc.) run the Create Routes tool.

    This generates an output line feature containing m-values. The measurements use the projection units of the input by default, so ensure the linear unit of the data's projection is the desired unit for spacing the perpendicular lines resulting from this process.

    In the tool's parameters, set the Measure Source to Length.
  2. Create route events at a specified distance by creating route event tables in Microsoft Excel. Two tables must be created - one containing a positive offset value, and the second containing a negative offset value. These tables are used to generate route events on each side of the main line. The route events are merged and connected to form the perpendicular lines.

    Create each table with the following fields: LOCATION, OFFSET, ROUTE. The location should be a sequential number from 1 to the final point used in the Measure parameter when running the Make Route Event Layer tool in Step 3. Offset must contain the distance at which the route event is created to each side of the main line. The Route field must contain the RouteID corresponding to the RouteID of the main line route created in Step 1.

    Some math may need to be done to determine spacing. For example, if the input line is 26,475 meters long and the desired result is a perpendicular line crossing the main line every meter, create the Excel tables with 26,475 records. In this way, a route event is generated every meter. However, if the desired result is a perpendicular line crossing the main line every 10 meters, create the Excel tables with 2,648 records, with Location values of 10, 20, and so forth.
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  3. Run the Make Route Event Layer tool for each Excel table created in Step 2. Be sure to set the Offset Field parameter.

    After the tool runs for each Excel table, verify the route events along each side of the main line feature.
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  4. To connect these points to form perpendicular lines, they must be in one feature class. Use the Merge tool to merge both event layers into one feature class.
  5. Run the Points to Line tool using the merged events feature class as the input and setting the Line Field parameter to Location.
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