Railways

Convergence – CC BY-SA by beeveephoto

Day 25–26 of 30DayMapChallenge: « Hexagons » and « Transports » (previously).

Estimating the disappearance of railway lines in France.

Config

library(sf)
library(glue)
library(ggplot2)
library(janitor)
library(ggspatial)
library(dplyr)
library(tidyr)
library(units)
library(osmdata)

Data

# Get and cache OSM data for abandoned railways in France
if (!file.exists("lost_railways.gpkg")) {
  railways <- r"([out:xml][timeout:6000];
  
  // Get France as area
  area["name"="France"]->.fr;
  
  (
  // Direct generic railway status tags
  way["railway"~"^(disused|abandoned|razed|dismantled|demolished|retired)$"](area.fr);
  
  // Include specific rail / tram / light_rail... in same statuses
  way["railway"~"^(rail|tram|light_rail|narrow_gauge)$"]["disused"="yes"](area.fr);
  way["railway"~"^(rail|tram|light_rail|narrow_gauge)$"]["abandoned"="yes"](area.fr);
  way["railway"~"^(rail|tram|light_rail|narrow_gauge)$"]["razed"="yes"](area.fr);
  way["railway"~"^(rail|tram|light_rail|narrow_gauge)$"]["dismantled"="yes"](area.fr);
  way["railway"~"^(rail|tram|light_rail|narrow_gauge)$"]["demolished"="yes"](area.fr);
  way["railway"~"^(rail|tram|light_rail|narrow_gauge)$"]["retired"="yes"](area.fr);
  
  // Lifecycle prefix tags for some railway subtype
  // Matches patterns like: disused:railway=rail, abandoned:railway=tram, etc.
  way[~"^(disused|abandoned|razed|dismantled|demolished|retired):railway$"~"^(rail|tram|light_rail|narrow_gauge)$"](area.fr);
  );
  (._;>;);
  out body;)" |> 
    osmdata_sf() 
  
  lost_railways <- railways$osm_lines |> 
    clean_names() |> 
    select(railway, name) |> 
    write_sf("lost_railways.gpkg")
} else {
  lost_railways <- read_sf("lost_railways.gpkg")
}

# Hexagonal grid
# See https://r.iresmi.net/posts/2024/discrete_global_grid/
hex_size <- 20 # km
hex <- read_sf("../../2024/discrete_global_grid/dggrid_fx.gpkg", 
                layer = glue("dggrid_{hex_size}k")) |> 
  st_transform("EPSG:2154")

dep <- "~/data/adminexpress/adminexpress_cog_simpl_000_2022.gpkg" |> 
  read_sf(layer = "departement_int")

We intersect the railways tracks with the hexagonal grid and calculate the total length per cell.

railways_length <- lost_railways |> 
  st_transform("EPSG:2154") |> 
  st_intersection(hex) |> 
  mutate(length = st_length(geom)) |> 
  st_drop_geometry() |> 
  group_by(seqnum) |> 
  summarise(length = drop_units(set_units(sum(length), km)))

Map

hex |> 
  left_join(railways_length,
            join_by(seqnum)) |>
  replace_na(list(length = 0)) |> 
  ggplot() +
  geom_sf(aes(fill = length, color = length)) +
  geom_sf(data = dep, fill = NA, color = "lightgrey", linewidth = 0.3, alpha = 0.8) +
  scale_fill_viridis_c(name = "former railways length\nper cell (km)", 
                       trans = "sqrt",
                       aesthetics = c("fill", "color")) +
  annotation_scale(height = unit(1, "mm"), 
                   text_col = "darkgrey", line_col = "grey", 
                   bar_cols = c("white", "grey")) +
  labs(title = "The vanished railways",
       subtitle = glue("Currently disused, abandoned, dismantled... \\
                       railways in France"),
       caption = glue("data: OpenStreetMap contributors
                      départements based on IGN AdminExpress 2022
                      Discrete Global Grid ISEA3H ≈ {hex_size} km, 
                      one hexagon ≈ {round(hex_size^2 * sqrt(3) / 2)} km²
                      https://r.iresmi.net - {Sys.Date()}")) +
  theme_void() +
  theme(plot.caption = element_text(size = 7, color = "grey40"),
        plot.margin = unit(c(.2, .2, .2, .2), units = "cm"),
        legend.position = "bottom")

Figure 1: Length per hexagon cell of currently disused, abandoned, dismantled, etc. railways in France