The workflow

LCP (the route)

Combine the cost factors into one surface, then trace the least-cost route.

The LCP tab combines the cost factors into a single surface and then routes across it.

Create Combined Costs Raster

• Select the rasters: Flu, Fs, Fc, Fci and N. Each is optional — a factor you leave out is treated as neutral (1.0), with a warning in the log.
• The rasters are automatically aligned and resampled to the first valid one’s grid, and N is capped at 10.
• Click Create Combined Raster to apply the COMET formula.

Create Least Cost Path

• Select Point Vector Layer (origin + destination) and Select Combined Raster.
• Click Create Least Cost Path to run the GRASS chain (r.cost → r.drain → r.thin → r.to.vect) → the route as a line vector.

How and why this is the globally optimal corridor: Least-cost path & global optimality.

Next: Price Estimation.