Dutch Portolan Demo

# Rijkswaterstaat Tunnels — Rijkswaterstaat / Netherlands

## What This Dataset Is

Point locations of **25 road tunnels** managed by Rijkswaterstaat in the Netherlands. Includes
both existing tunnels and planned future tunnels. Each record contains the tunnel name, road
number, municipality, year of opening, and a link to the tunnel's information page.

**Provider:** Rijkswaterstaat (Directorate-General for Public Works and Water Management)
**License:** Public domain (Dutch government open data)

## How to Access

The data is a GeoParquet file in **EPSG:28992** (Amersfoort / RD New). Use DuckDB with the
spatial extension.

```python
import duckdb

con = duckdb.connect()
con.execute("INSTALL spatial; LOAD spatial;")

URL = 'https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/fme_disk_tunnels/fme_disk_tunnels.parquet'

df = con.execute(f"""
    SELECT * FROM read_parquet('{URL}')
    LIMIT 5
""").df()
```

The file is tiny (25 features) — loads instantly.

## Schema — Field Meanings

| Field | Type | Meaning |
|-------|------|---------|
| `geometry` | WKB Point | Tunnel location in **EPSG:28992**. |
| `tunnelnaam` | string | **Tunnel name** (e.g., "Coentunnel", "Westerscheldetunnel"). |
| `wegnummer` | string | **Road number** (e.g., "A10", "A4", "N62"). |
| `gemeente` | string | Municipality where the tunnel is located. |
| `jaar_openstelling` | string | **Year opened.** String, not integer — some values are future prognoses like `"2035 (prognose)"`. |
| `status` | string | `Bestaand` (existing) or `Gepland` (planned). |
| `url` | string | URL to tunnel information page on Rijkswaterstaat website. |
| `beheerder` | string | Operator / manager of the tunnel. |

## Useful Query Patterns

### List all tunnels

```sql
SELECT tunnelnaam, wegnummer, gemeente, jaar_openstelling, status
FROM read_parquet('https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/fme_disk_tunnels/fme_disk_tunnels.parquet')
ORDER BY tunnelnaam
```

### Group tunnels by road number

```sql
SELECT wegnummer, COUNT(*) AS tunnel_count,
       STRING_AGG(tunnelnaam, ', ') AS tunnels
FROM read_parquet('https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/fme_disk_tunnels/fme_disk_tunnels.parquet')
GROUP BY wegnummer
ORDER BY tunnel_count DESC
```

### Find planned (future) tunnels

```sql
SELECT tunnelnaam, wegnummer, gemeente, jaar_openstelling
FROM read_parquet('https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/fme_disk_tunnels/fme_disk_tunnels.parquet')
WHERE status = 'Gepland'
```

### Tunnels by municipality

```sql
SELECT gemeente, COUNT(*) AS tunnels
FROM read_parquet('https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/fme_disk_tunnels/fme_disk_tunnels.parquet')
GROUP BY gemeente
ORDER BY tunnels DESC
```

## Geometry Notes

- CRS is **EPSG:28992** (Amersfoort / RD New). Coordinates are in metres.
- All geometries are Point — representing tunnel locations, not extents.
- Reproject to EPSG:4326 for web maps.


## Visualization Styles

One Mapbox GL v8 style is available for interactive map visualization via the PMTiles file.

Style files are Mapbox GL v8 JSON with relative PMTiles source paths. They can be
used with MapLibre GL JS, OpenLayers (via ol-mapbox-style), or any Mapbox GL v8-compatible renderer.

- **`styles/default.json`** — Red circles with white borders, sized by zoom level. Labels show tunnel names at higher zoom. Shows the spatial distribution of road tunnels across the Netherlands.

Style files are at: `https://data.source.coop/cholmes/portolan-nl/rijkswaterstaat/fme_disk_tunnels/styles/`
## Caveats

- **`jaar_openstelling` is a string**, not an integer — some values include prognosis text
  like `"2035 (prognose)"`. Do not cast directly to integer without cleaning.
- Small dataset (25 features) — only tunnels managed by Rijkswaterstaat on the national
  road network, not all tunnels in the Netherlands.
- Status values are in Dutch: `Bestaand` = existing, `Gepland` = planned.