Scenario comparison

compare_evac_scenarios() runs the same study inputs under named parameter overrides. It returns each raw result, a scenario summary, and combined spatial layers when available.

comparison <- compare_evac_scenarios(
  hazard_zone = hazard_zone,
  roads = roads,
  dem = dem,
  target_crs = "EPSG:32748",
  max_origins = 100,
  max_destinations = 25,
  scenarios = list(
    baseline = list(walking_speed_mps = 1.22),
    slow_walkers = list(walking_speed_mps = 0.75),
    conservative_lcp = list(
      lcp_neighbours = 8,
      lcp_max_slope = 30
    )
  )
)

comparison$summary
Scenario sensitivity in modeled evacuation time.
Scenario sensitivity in modeled evacuation time.

The compact packaged example below retains the scenario-level time metrics and the assumptions used to generate them.

Scenario Origins Exits Walking speed Median min. Mean min. Maximum min. Assumption
baseline 25 8 1.22 7.27 9.75 22.84 Baseline walking-speed and routing assumptions.
slow_walkers 25 8 0.75 11.83 15.86 37.15 Changes time conversion; route distance is held by the same routing setup.
conservative_routing 25 8 1.22 7.48 10.26 23.96 Uses 8 neighbours and a 30 percent maximum slope.

Treat scenario outputs as sensitivity analysis. A slower walking speed changes time conversion; conductance and neighbourhood settings can change modeled route geometry as well as distance. A scenario with incomplete outputs is retained with missing summary values rather than discarding the whole comparison.