Example workflow

This gallery uses the packaged example data in a focused projected window. It illustrates the package workflow and the layers to inspect; it is not a finished evacuation plan or a substitute for local review.

Example inputs

Input	Example value
Coordinate reference system	EPSG:32748
Hazard-zone area (square km)	4.048
Road features	254
Candidate safety exits	12
Sampled road origins	40

Candidate safety exits

The hazard zone is the land-only area used for evacuation origins and mapped outputs. The escape zone combines the inundated area with water so the shoreline is not treated as an artificial exit. Candidate safety exits are road intersections with the selected escape boundary, not confirmed safe locations.

Modeled evacuation time

The time surface converts modeled least-cost distance to safety with the chosen walking speed. It is sensitive to the elevation surface, road mask, escape-point logic, cost function, and routing neighbourhood.

Modeled output	Example value
Minimum modeled time (minutes)	0.31
Median modeled time (minutes)	10.09
Mean modeled time (minutes)	9.65
Maximum modeled time (minutes)	22.84
Origins	40.00
Destinations	12.00
Walking speed (m/s)	1.22

Scenario comparison

Scenario sensitivity in modeled evacuation time.

The slower-walker scenario changes the time conversion. The conservative-routing scenario changes least-cost path settings and may therefore change both modeled route geometry and distance.

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

Outputs users can write

write_evac_outputs() writes selected spatial outputs to an explicit directory. For prefix = "study_area", typical filenames include study_area_escape_points.gpkg, study_area_distance_points.gpkg, study_area_evac_polygons.gpkg, and study_area_time_grid.gpkg. The returned object keeps the following layers available for inspection before anything is written.

Object	Purpose
hazard_zone	Land-only area used for evacuation origins and mapped output.
escape_points	Candidate safety exits identified at the selected escape boundary.
road_points	Sampled road-based origins used for least-cost calculations.
distance_points	Modeled distance to safety for sampled origins and zero-distance exits.
evac_polygons / time_grid	Polygonized modeled distance and time surface for map output.

The reproducible generator for this gallery is inst/scripts/make-pkgdown-example-outputs.R. It uses the packaged data and creates the small figures and CSV summaries included here.