Add GB primary/secondary routes (#1465)

This PR adds an additional pseudo-network for UK non-primary [routes](https://en.wikipedia.org/wiki/Great_Britain_road_numbering_scheme), which are signed with black on white signage with "A" and "B" prefixes. This scheme is described on the [OSM wiki](https://wiki.openstreetmap.org/wiki/Roads_in_the_United_Kingdom). Adding this third psuedo network is needed for generating shields for UK white/black signage for non-primary routes. 
Additionally, this fixes a minor bug under which single-digit refs would have been included.  Single-digit refs don't exist in the UK, because the numbering scheme is always prefixed by a letter, e.g. "A4".

I also included documentation updates and fixed the typo where a view was named "bg" instead of "gb".

layers/transportation/network_type.sql

@@ -16,7 +16,7 @@ $$
             CREATE TYPE route_network_type AS enum (
                 'us-interstate', 'us-highway', 'us-state',
                 'ca-transcanada', 'ca-provincial-arterial', 'ca-provincial',
-                'gb-motorway', 'gb-trunk'
+                'gb-motorway', 'gb-trunk', 'gb-primary'
                 );
     END
 $$;

layers/transportation/update_route_member.sql

@@ -1,23 +1,27 @@
-CREATE TABLE IF NOT EXISTS ne_10m_admin_0_bg_buffer AS
+CREATE TABLE IF NOT EXISTS ne_10m_admin_0_gb_buffer AS
 SELECT ST_Buffer(geometry, 10000)
 FROM ne_10m_admin_0_countries
 WHERE iso_a2 = 'GB';
 
+-- etldoc:  osm_route_member ->  gbr_route_members_view
 CREATE OR REPLACE VIEW gbr_route_members_view AS
 SELECT 0,
        osm_id,
-       substring(ref FROM E'^[AM][0-9AM()]+'),
-       CASE WHEN highway = 'motorway' THEN 'omt-gb-motorway' ELSE 'omt-gb-trunk' END
+       substring(ref FROM E'^[ABM][0-9ABM()]+'),
+       -- See https://wiki.openstreetmap.org/wiki/Roads_in_the_United_Kingdom
+       CASE WHEN highway = 'motorway' THEN 'omt-gb-motorway'
+            WHEN highway = 'trunk' THEN 'omt-gb-trunk' 
+            WHEN highway IN ('primary','secondary') THEN 'omt-gb-primary' END AS network
 FROM osm_highway_linestring
-WHERE length(ref) > 0
-  AND ST_Intersects(geometry, (SELECT * FROM ne_10m_admin_0_bg_buffer))
-  AND highway IN ('motorway', 'trunk')
+WHERE length(ref) > 1
+  AND ST_Intersects(geometry, (SELECT * FROM ne_10m_admin_0_gb_buffer))
+  AND highway IN ('motorway', 'trunk', 'primary', 'secondary')
 ;
 -- Create GBR relations (so we can use it in the same way as other relations)
 DELETE
 FROM osm_route_member
-WHERE network IN ('omt-gb-motorway', 'omt-gb-trunk');
--- etldoc:  osm_highway_linestring ->  osm_route_member
+WHERE network IN ('omt-gb-motorway', 'omt-gb-trunk', 'omt-gb-primary');
+-- etldoc:  gbr_route_members_view ->  osm_route_member
 INSERT INTO osm_route_member (osm_id, member, ref, network)
 SELECT *
 FROM gbr_route_members_view;
@@ -43,6 +47,7 @@ SELECT CASE
            WHEN network LIKE 'CA:__' OR network LIKE 'CA:__:%' THEN 'ca-provincial'::route_network_type
            WHEN network = 'omt-gb-motorway' THEN 'gb-motorway'::route_network_type
            WHEN network = 'omt-gb-trunk' THEN 'gb-trunk'::route_network_type
+           WHEN network = 'omt-gb-primary' THEN 'gb-primary'::route_network_type
            END;
 $$ LANGUAGE sql IMMUTABLE
                 PARALLEL SAFE;
@@ -62,7 +67,7 @@ BEGIN
     FROM osm_route_member AS r
         USING
             transportation_name.network_changes AS c
-    WHERE network IN ('omt-gb-motorway', 'omt-gb-trunk')
+    WHERE network IN ('omt-gb-motorway', 'omt-gb-trunk', 'omt-gb-primary')
       AND r.osm_id = c.osm_id;
 
     INSERT INTO osm_route_member (osm_id, member, ref, network)

layers/transportation_name/transportation_name.yaml

@@ -32,6 +32,7 @@ layer:
       - ca-provincial
       - gb-motorway
       - gb-trunk
+      - gb-primary
       - road (default)
     class:
       description: |