Mapping GRID3 Friction Surfaces by LGA in Nigeria

Author

Matthew Walter

Published

February 20, 2026

1 Mapping GRID3 Friction Surfaces by LGA

1.1 Overview

This lesson demonstrates how to use GRID3 data to map and analyze friction surfaces at the Local Government Area (LGA) level in Nigeria. It walks through accessing GRID3 Raster Friction Surface and administrative boundaries data, then clipping and visualizing a friction surface for a selected LGA in a reproducible workflow.

Open In Colab

1.2 Data

The lesson uses:

  • GRID3 high-resolution friction surfaces (walking and mixed-mode)
  • Administrative boundaries for Nigerian states and LGAs

Friction surfaces represent travel difficulty or cost across space, enabling realistic travel-time and accessibility modeling beyond road-network-only approaches.

1.3 Workflow (Google Colab)

Implemented in Google Colab, the notebook shows how to:

  1. Query state and LGA boundaries from ArcGIS FeatureLayers
  2. Select a state and LGA interactively
  3. Download and extract GRID3 friction rasters
  4. Clip the raster to the selected LGA
  5. Export a GeoTIFF and create publication-ready plots

Clear helper functions and comments make it easy to adapt for other regions or batch processing.

1.4 Learning Outcomes

By the end, users will be able to:

  • Understand GRID3 friction datasets
  • Extract and crop friction rasters to an LGA
  • Generate GeoTIFF outputs and visualizations for accessibility or infrastructure analysis

Common issues (e.g., CRS mismatches, empty queries, file extraction steps) are also highlighted.

1.5 Run in Google Colab

Open the lesson in Google Colab to execute the code and follow along with the analysis: Open In Colab