Bottlenecks and route validation

Route-density analysis can identify modeled high-use corridors. It does not measure observed pedestrian traffic unless modeled routes are compared with independent route or movement data.

Retain modeled routes

Route geometries are optional because they can increase memory use. Request them when the result will be used for corridor analysis.

result <- run_evacpath(
  hazard_zone = hazard_zone,
  roads = roads,
  dem = dem,
  target_crs = "EPSG:32748",
  keep_routes = TRUE
)

Map modeled high-use corridors

bottlenecks <- map_evac_bottlenecks(
  evac_result = result,
  quantile_threshold = 0.9
)

bottlenecks$summary
bottlenecks$high_density_polygons

Modeled high-use corridors from the compact packaged example.

Output	Purpose
density_raster	Count of modeled route overlap on the selected raster grid.
high_density_raster	Cells meeting the selected density threshold.
high_density_polygons	Optional polygons outlining selected high-density cells.
summary	Route count, density threshold, and high-density area metrics.

The threshold selects high-density raster cells from route overlap. Inspect the template resolution, threshold choice, and underlying route set before describing a corridor as a planning bottleneck.

Compare with reference routes

validate_evac_routes() accepts sf line layers. It can match by an ID column or compare each modeled route with the nearest reference route.

validation <- validate_evac_routes(
  modeled_routes = modeled_routes,
  reference_routes = reference_routes,
  method = "all",
  buffer_m = 25,
  by = "route_id"
)

validation$summary

Buffer overlap measures how much modeled line length falls within a reference route buffer. Hausdorff distance measures geometric separation. Path deviation index is attempted when the route pair is compatible with leastcostpath.