Reworking routing examples

Dockerfile

@@ -15,6 +15,7 @@ RUN apt-get update \
         python3 python3-distutils \
         postgresql-server-dev-15 \
         curl unzip \
+        postgresql-15-pgrouting \
     && rm -rf /var/lib/apt/lists/*
 
 RUN wget https://luarocks.org/releases/luarocks-3.9.1.tar.gz \

docs/src/routing.md

@@ -96,24 +96,59 @@ ALTER TABLE routing.road_line_noded
 
 ## Start/end points
 
-Picked vertex IDs `11322` and `7653`, they span a particular segment
+The following query identifies the vertex IDs for a start and end point to use
+for later queries.  Use the `start_id` and `end_id` values from this query
+in subsequent queries.
+
+
+```sql
+WITH s_point AS (
+SELECT v.id AS start_id
+    FROM routing.road_line_noded_vertices_pgr v
+    INNER JOIN (SELECT
+        ST_Transform(ST_SetSRID(ST_MakePoint(-77.0211, 38.92245), 4326), 3857)
+            AS geom
+        ) p ON v.the_geom <-> geom < 10
+    ORDER BY v.the_geom <-> geom
+    LIMIT 1
+), e_point AS (
+SELECT v.id AS end_id
+    FROM routing.road_line_noded_vertices_pgr v
+    INNER JOIN (SELECT
+        ST_Transform(ST_SetSRID(ST_MakePoint(-77.0183, 38.9227), 4326), 3857)
+            AS geom
+        ) p ON v.the_geom <-> geom < 10
+    ORDER BY v.the_geom <-> geom
+    LIMIT 1
+)
+SELECT s_point.start_id, e_point.end_id
+    FROM s_point, e_point
+;
+```
+
+```
+┌──────────┬────────┐
+│ start_id │ end_id │
+╞══════════╪════════╡
+│    14630 │  14686 │
+└──────────┴────────┘
+```
+
+Picked vertex IDs `14630` and `14686`, they span a particular segment
 of road that is tagged as `highway=residential` and `access=private`.
 This was picked to illustrate how the calculated access control columns, `route_motor`, `route_cycle` and `route_foot`,
 can influence route selection.
 
 > Note:  The vertex IDs in my test database will not necessary match the vertex IDs in your database!
 
-```bash
-Name    |Value                 |
---------+----------------------+
-osm_id  |6062791               |
-osm_type|residential           |
-name    |Howard Place Northwest|
-access  |private               |
+```sql
+SELECT *
+    FROM osm.road_line
+    WHERE osm_id = 6062791
+;
 ```
 
-
-![Screenshot from QGIS showing two labeled points, 11322 and 7653. The road between the two points is shown with a light gray dash indicating the access tag indicates non-public travel.](dc-example-route-start-end-vertices.png)
+![Screenshot from QGIS showing two labeled points, 14630 and 14686. The road between the two points is shown with a light gray dash indicating the access tag indicates non-public travel.](dc-example-route-start-end-vertices.png)
 
 > See `flex-config/helpers.lua` functions (e.g. `routable_motor()`) for logic behind access control columns.
 
@@ -132,8 +167,9 @@ SELECT d.*, n.the_geom AS node_geom, e.geom AS edge_geom
     FROM pgr_dijkstra(
         'SELECT id, source, target, cost_length AS cost,
                 geom
-            FROM routing.road_line_noded',
-                     11322, 7653, directed := False
+            FROM routing.road_line_noded
+            ',
+            14630, 14686, directed := False
         ) d
     INNER JOIN routing.road_line_noded_vertices_pgr n ON d.node = n.id
     LEFT JOIN routing.road_line_noded e ON d.edge = e.id
@@ -146,9 +182,8 @@ SELECT d.*, n.the_geom AS node_geom, e.geom AS edge_geom
 ## Route motorized
 
 The following query modifies the query passed in to `pgr_dijkstra()`
-to join to `osm.road_line`.  The join clause includes `route_motor`
-which ensures sidewalks aren't chosen, as well as enforces simple
-access control.
+to join to `osm.road_line`.  The join clause includes a filter on
+the `route_motor` column.
 
 
 ```sql
@@ -157,10 +192,10 @@ SELECT d.*, n.the_geom AS node_geom, e.geom AS edge_geom
         'SELECT n.id, n.source, n.target, n.cost_length AS cost,
                 n.geom
             FROM routing.road_line_noded n
-            INNER JOIN osm.road_line r
-            	ON n.old_id = r.osm_id
-            		AND route_motor',
-                     11322, 7653, directed := False
+            INNER JOIN routing.road_line r ON n.old_id = r.id
+                    AND r.route_motor
+            ',
+            14630, 14686, directed := False
         ) d
     INNER JOIN routing.road_line_noded_vertices_pgr n ON d.node = n.id
     LEFT JOIN routing.road_line_noded e ON d.edge = e.id
@@ -192,14 +227,20 @@ ALTER TABLE routing.road_line_noded
 
 UPDATE routing.road_line_noded rn
     SET oneway = r.oneway
-    FROM osm.road_line r
-    WHERE rn.old_id = r.osm_id AND rn.oneway IS NULL
+    FROM routing.road_line r
+    WHERE rn.old_id = r.id AND rn.oneway IS NULL
 ;
 ```
 
+### Forward and reverse costs
+
 Calculate forward cost.
 
 ```sql
+ALTER TABLE routing.road_line_noded
+    DROP COLUMN IF EXISTS cost_length
+;
+
 -- Cost with oneway considerations
 ALTER TABLE routing.road_line_noded
     ADD cost_length NUMERIC
@@ -231,7 +272,11 @@ ALTER TABLE routing.road_line_noded
 ;
 ```
 
-Route, now directed.
+### New undirected route
+
+Found new start point slightly to the north that will require one-way aware
+for proper routing. The route from this query incorrectly goes the wrong
+way on 6th Street Northwest.
 
 ```sql
 SELECT d.*, n.the_geom AS node_geom, e.geom AS edge_geom
@@ -241,14 +286,44 @@ SELECT d.*, n.the_geom AS node_geom, e.geom AS edge_geom
                 n.geom
             FROM routing.road_line_noded n
             INNER JOIN osm.road_line r
-                ON n.old_id = r.osm_id
+                ON n.old_id = r.id
                     AND route_motor
                     AND n.cost_length IS NOT NULL
         ',
-          39877, 8227,
+          14624, 14686,
+          directed := False
+        ) d
+    INNER JOIN routing.road_line_noded_vertices_pgr n ON d.node = n.id
+    LEFT JOIN routing.road_line_noded e ON d.edge = e.id
+;
+```
+
+
+![Screenshot from DBeaver showing a route with a small segment going the wrong way on a one-way street because the query was using `directed := False`.](dc-route-not-respecting-one-way.png)
+
+### Directed
+
+Route, now directed. This respects the one-way rules.
+
+
+```sql
+SELECT d.*, n.the_geom AS node_geom, e.geom AS edge_geom
+    FROM pgr_dijkstra(
+        'SELECT n.id, n.source, n.target, n.cost_length AS cost,
+                n.cost_length_reverse AS reverse_cost,
+                n.geom
+            FROM routing.road_line_noded n
+            INNER JOIN routing.road_line r
+                ON n.old_id = r.id
+                    AND route_motor
+                    AND n.cost_length IS NOT NULL
+        ',
+          14624, 14686,
           directed := True
         ) d
     INNER JOIN routing.road_line_noded_vertices_pgr n ON d.node = n.id
     LEFT JOIN routing.road_line_noded e ON d.edge = e.id
 ;
 ```
+
+![alt coming soon](dc-route-respecting-one-way.png)