Center for Integrated Earth System Information (CIESIN), Columbia UniversityThe aim of this work is to generate two friction surfaces for modeling physical accessibility: one incorporating walking speed only, and another combining walking and motorized travel speeds. Motorized speeds are applied exclusively on roads that are present and passable by vehicles; in all other areas, walking speeds are used. The GRID3 NGA - Travel Time Friction Surface v1.0 dataset is a spatial data layer in tiff format. The datasets contain 2 layers: ⦁ GRID3_NGA_walk_travel_time_friction_surface_v1_0.tif - Applies walking speeds across the entire surface, adjusted for slope and elevation. ⦁ GRID3_NGA_mix_travel_time_friction_surface_v1_0.tif - Applies motorized speeds on roads and walking speeds in all other areas. The resolution is 30 m. The unit of measurement in both surfaces is minutes per meter. Dataset citation: Center for Integrated Earth System Information (CIESIN), Columbia University. 2025. GRID3 NGA - Travel Time Friction Surface v1.0. New York: Columbia University. URL. Accessed DAY-MONTH-YEAR. Contacts and data queries: The authors of this dataset appreciate feedback regarding the data, including suggestions, discovery of errors, difficulties in using the data, and format preferences. For dataset-related questions, please send an email to: info@ciesin.columbia.edugrid3-nga-travel-time-friction-surface-v1-0Humanitarian Data ExchangePublicGRID3 NGA - Travel Time Friction Surface v1.0DatasetsNigeria2010-01-01 to 2025-08-31