Accessibility analysis (m2, m3, m4, m6) error message (Ethiopia)

[GaelleSehi]

Hello,

Current Behavior

I am conducting an accessibility analysis for Ethiopia, starting with Addis Ababa. The land cover data was successfully merged, and validation completed without issues.
However, when starting the analysis, I encounter an error message a few seconds into the process (see attached screenshot).

Expected Behavior

I ran a similar analysis for Côte d'Ivoire and Sierra Leone before and was able to obtain the accessibility analysis output.

Possible Solution

The following could be potential sources of the problem:

• Land Use Layer Resolution: The land use data is from Dynamic World (10m resolution), which may be too detailed compared to other layers.
• Road Network Complexity: The road network was simplified by removing certain roads, which might cause inconsistencies.

List of layers:
Pop from Worldpop - World pop (1km)
Roads and Water (line and polygon) - OpenStreetMap
Land use land cover - Dynamic world (exported as 100m)
DEM - SRTM (90m)

Steps to Reproduce

1. Merge the land cover, barriers, and roads layers.
2. Select the scenario table and the list of health facilities.
3. For the travel scenario, import the content from the scenario table.
4. Set analysis settings:
5. Travel Type: Anisotropic analysis
6. Travel Direction: Towards facilities
7. Maximum Travel Time: 60 minutes (later planned for 120min, 180min)
8. Unselect 16 out of 21 health facilities because they are either on barriers or outside the DEM extent.
9. Begin the analysis.

[nicolasray]

Dear Gaelle, it seems AccessMod is trying to allocate memory for a very large raster, and you are running out of it. In AccessMod, you should always have all your raster at the same resolution (usually 100m, possibly 30m), and all projected in the same metric projection. It seems you have used input raster of various resolutions. Try to prepare prepare all your raster and import them again. Also I would suggest using the 100m (constrained) WorldPop raster.