You need to define the line_side (Optional) parameter in Buffer tool. You need ArcGIS Desktop Advanced license to avail this option.
The sides of the input features that will be buffered.
- FULL —For line input features, buffers will be generated on both sides of the line. For polygon input features, buffers will be generated around the polygon and will contain and overlap the area of the input features. For point input features, buffers will be generated around the point. This is the default.
- LEFT —For line input features, buffers will be generated on the topological left of the line. This option is not valid for polygon input features.
- RIGHT —For line input features, buffers will be generated on the topological right of the line. This option is not valid for polygon input features.
- OUTSIDE_ONLY —For polygon input features, buffers will be generated only outside the input polygon (the area inside the input polygon will be erased from the output buffer). This option is not valid for line input features.
Think Location