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.

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.