diff --git a/data/json/overmap/overmap_terrain/overmap_terrain_special.json b/data/json/overmap/overmap_terrain/overmap_terrain_special.json
index 0208c66b9f6cb..1c8166dc58174 100644
--- a/data/json/overmap/overmap_terrain/overmap_terrain_special.json
+++ b/data/json/overmap/overmap_terrain/overmap_terrain_special.json
@@ -51,7 +51,7 @@
     "type": "overmap_terrain",
     "id": "special_field_highway",
     "copy-from": "special_field",
-    "extend": { "flags": [ "HIGHWAY" ] }
+    "extend": { "flags": [ "HIGHWAY", "SHOULD_NOT_SPAWN" ] }
   },
   {
     "type": "overmap_terrain",
@@ -172,13 +172,13 @@
     "copy-from": "generic_air",
     "id": "hw_reserved",
     "//": "Has rotation so cities can judge whether it's running perpendicular/parallel",
-    "flags": [ "HIGHWAY_RESERVED", "REQUIRES_PREDECESSOR" ]
+    "flags": [ "HIGHWAY_RESERVED", "REQUIRES_PREDECESSOR", "SHOULD_NOT_SPAWN" ]
   },
   {
     "type": "overmap_terrain",
     "id": "hw_reserved_water",
     "copy-from": "hw_reserved",
-    "extend": { "flags": [ "RIVER" ] }
+    "extend": { "flags": [ "RIVER", "SHOULD_NOT_SPAWN" ] }
   },
   {
     "type": "overmap_terrain",
diff --git a/data/json/overmap/overmap_terrain/overmap_terrain_transportation.json b/data/json/overmap/overmap_terrain/overmap_terrain_transportation.json
index 37f69c1d9bd4d..ac8c409139588 100644
--- a/data/json/overmap/overmap_terrain/overmap_terrain_transportation.json
+++ b/data/json/overmap/overmap_terrain/overmap_terrain_transportation.json
@@ -547,7 +547,7 @@
     "name": "road",
     "sym": "│",
     "color": "dark_gray",
-    "flags": [ "ROAD", "REQUIRES_PREDECESSOR", "SIDEWALK" ]
+    "flags": [ "ROAD", "REQUIRES_PREDECESSOR", "SIDEWALK", "SHOULD_NOT_SPAWN" ]
   },
   {
     "type": "overmap_terrain",
@@ -570,7 +570,7 @@
     "name": "road bridge",
     "travel_cost_type": "road",
     "sym": "─",
-    "flags": [ "ROAD" ]
+    "flags": [ "ROAD", "SHOULD_NOT_SPAWN" ]
   },
   {
     "type": "overmap_terrain",
@@ -578,7 +578,7 @@
     "copy-from": "generic_open_land",
     "name": "highway",
     "sym": "│",
-    "flags": [ "HIGHWAY" ]
+    "flags": [ "HIGHWAY", "SHOULD_NOT_SPAWN" ]
   },
   {
     "type": "overmap_terrain",
diff --git a/data/mods/TEST_DATA/overmap_terrain_coverage_test/overmap_terrain_coverage_whitelist.json b/data/mods/TEST_DATA/overmap_terrain_coverage_test/overmap_terrain_coverage_whitelist.json
index 9b311b8dbb15a..79dc0fbed0be3 100644
--- a/data/mods/TEST_DATA/overmap_terrain_coverage_test/overmap_terrain_coverage_whitelist.json
+++ b/data/mods/TEST_DATA/overmap_terrain_coverage_test/overmap_terrain_coverage_whitelist.json
@@ -4,6 +4,7 @@
     "overmap_terrain_coverage_whitelist": [
       "ants_lab",
       "ants_lab_stairs",
+      "hw_railings",
       "ice_lab",
       "ice_lab_core",
       "ice_lab_finale",