ArcGIS Pro Tutorial: Generating Road Polygons from Lines – Utilizing Buffer Tool in ArcGIS Pro

ArcGIS Pro Tutorial: Generating Road Polygons from Lines – Utilizing Buffer Tool

Creating road polygons from line features is a fundamental GIS task that transforms linear road networks into polygonal representations. This tutorial will guide you through using the Buffer tool in ArcGIS Pro to accomplish this essential spatial analysis task.

Prerequisites

• ArcGIS Pro installed and licensed
• Road network data in line format (shapefile, feature class, etc.)
• Basic understanding of GIS concepts

Step-by-Step Process

Step 1: Prepare Your Data

Before beginning the buffering process, ensure your road line data is properly formatted:

• Verify the coordinate system is appropriate for your project
• Check for any topological errors or gaps in the road network
• Ensure attribute fields are properly populated if needed for classification

Step 2: Access the Buffer Tool

Navigate to the Buffer tool through the following path:

1. Open ArcGIS Pro and load your road line layer
2. Go to the Analysis tab
3. Click on Tools
4. Search for “Buffer” in the Geoprocessing pane
5. Select the Buffer tool from the search results

Step 3: Configure Buffer Parameters

Set up the buffer parameters according to your requirements:

• Input Features: Select your road line layer
• Output Feature Class: Specify the location and name for your output polygon layer
• Distance: Enter the buffer distance (e.g., 10 meters for typical road width)
• Side Type: Choose “FULL” to create buffers on both sides of lines
• End Type: Select “ROUND” or “FLAT” based on your preference

Step 4: Advanced Buffer Options

For more precise road polygon creation, consider these advanced settings:

• Use Dissolve Type = “ALL” to merge overlapping buffers into single polygons
• Apply Field-based buffering if road widths vary by type
• Set appropriate Distance Units (Meters, Feet, etc.)

Step 5: Execute and Review

Run the buffer operation and examine the results:

• Check for any gaps or overlaps in the resulting polygons
• Verify polygon topology and geometric accuracy
• Adjust buffer distance if necessary and re-run the process

Tips for Optimal Results

• Use smaller buffer distances for narrow streets and larger distances for highways
• Consider using different buffer distances for different road types
• Apply the Eliminate Polygon Part tool to remove small sliver polygons
• Use the Integrate tool to clean up topology errors before buffering

Common Applications

Road polygons generated from line features are valuable for:

• Urban planning and development analysis
• Transportation network modeling
• Land use and zoning studies
• Emergency response planning
• Infrastructure management

Troubleshooting Common Issues

• Overlapping Polygons: Use dissolve options or the Union tool to merge overlaps
• Gaps in Network: Check source line data for connectivity issues
• Excessive Processing Time: Simplify complex geometries before buffering
• Incorrect Sizes: Verify coordinate system and units match your requirements

FAQ Section

How do I create different width buffers for different road types?

You can use field-based buffering by selecting a field containing width values instead of entering a fixed distance. This allows each road segment to be buffered according to its specific width attribute.

What coordinate system should I use for accurate buffering?

Use a projected coordinate system appropriate for your study area, preferably one that preserves distances such as UTM or State Plane coordinates. Avoid geographic coordinate systems (latitude/longitude) for buffering operations as they can produce inaccurate results.

How can I remove small gaps between road segments after buffering?

Use the Integrate tool before buffering to snap nearby vertices together, or apply the Buffer tool with the “FLAT” end type option. You can also use the Dissolve tool afterward to merge adjacent polygons.

Can I buffer roads with varying widths along their length?

Yes, but this requires more advanced techniques. You can create multiple buffer operations for different sections or use the Segment Along Line tool to break roads into segments with uniform widths before buffering.

How do I handle intersections where road buffers overlap?

Use the Dissolve tool with the “ALL” option to merge overlapping buffers into single polygons. For more control, you can use the Intersect tool followed by manual editing to create proper intersections.

What if my road network has complex geometries that slow down buffering?

Simplify your line geometries using the Simplify Line tool before buffering. You can also break large datasets into smaller chunks, process them separately, and merge the results afterward.

How do I maintain road attributes in the buffered polygons?

In the Buffer tool parameters, enable the “Dissolve Field(s)” option and select the attribute fields you want to preserve. This ensures that important road characteristics are carried over to the polygon features.