Extracting and Mapping GRID3 Data by administrative units

Author

Matthew Walter

Published

April 15, 2026

Overview

This lesson demonstrates how to use GRID3 data to map and analyze GRID3 data for specific administrative units, such as states, local government areas (LGAs), or wards in Nigeria and provinces, antenne, or zonesante in Democratic Republic of Congo (DRC). It focuses on extracting and visualizing key GRID3 datasets, including friction surfaces, roads, or settlement blocks. It walks through accessing GRID3 data, then subsetting and visualizing data for a selected administrative unit in a reproducible workflow.

Open In Colab

Data

The lesson uses:

  • GRID3 high-resolution friction surfaces (walking and mixed-mode). Friction surfaces represent travel difficulty or cost across space, enabling realistic travel-time and accessibility modeling beyond road-network-only approaches.
  • GRID3 major and all roads
  • GRID3 settlement blocks
  • Administrative boundaries for Nigeria and DRC

Workflow (Google Colab)

Implemented in Google Colab, the notebook shows how to:

  1. Query administrative boundaries from ArcGIS FeatureLayers
  2. Select a boundaries by name interactively
  3. Download and extract GRID3 data selected
  4. Subset the data to the selected boundary
  5. Export data and create publication-ready plots

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

Learning Outcomes

By the end, users will be able to:

  • Understand GRID3 datasets
  • Extract and subset GRDI3 data to an administrative boundary
  • Generate data outputs and visualizations for accessibility or analysis

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

Run in Google Colab

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

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