`WEP 4` Routing on External Data Sources¶

Swisstopo data integration for hiking and ski touring routes.

Swisstopo¶

This document describes a practical, reproducible workflow to convert SwissTopo hiking trail data (GPKG) into OSM-compatible data and use it with Valhalla for hiking routing. It also lays the foundation for later improvements such as source preference and ski touring routing.

Data Source: swissTLM3D¶

The dataset is derived from swissTLM3D (Topographic Landscape Model of Switzerland).

Official Documentation¶

The Datensatzkatalog swissTLM3D (PDF) defines:

Feature classes
Attribute names
Value domains (coded values)
Semantics of fields such as wanderwege, befahrbarkeit, belagsart, etc.

Relevant fields¶

From your GPKG, the following fields are important for routing (from TLM_STRASSEN):

objektart – Way / road type including implied width, expressed as a named class (e.g. "1 m Weg", "2 m Weg", "Markierte Spur", "Klettersteig")
wanderwege – hiking route classification (Wanderweg, Bergwanderweg, Alpinwanderweg)
stufe – NOT hiking difficulty (vertical / technical level at crossings)
befahrbarkeit – passability / access
belagsart – surface type
richtungsgetrennt – direction-separated geometry
name – trail name

All remaining fields are administrative metadata and are ignored for routing.

Target OSM Tagging Model¶

Reference: OSM Hiking Wiki

Base tags (always applied)¶

highway=path
foot=yes
source=swisstopo

Hiking difficulty¶

SwissTopo does not encode hiking difficulty in stufe.

Difficulty is derived from named classifications:

wanderwege (primary)
objektart (secondary, e.g. Klettersteig)

These are mapped to sac_scale, which Valhalla understands natively:

Swiss classification	OSM tag
Wanderweg	sac_scale=hiking
Bergwanderweg	sac_scale=mountain_hiking
Alpinwanderweg	sac_scale=alpine_hiking

Access / passability¶

access=yes | no | permissive

Surface¶

surface=paved | gravel | ground | rock

Direction (only if applicable)¶

oneway=yes

Name¶

name=<trail name>

Toolchain¶

Required tools¶

pip install ogr2osm
sudo apt install gdal-bin osmium-tool

Processing flow¶

GPKG (swisstopo)
  ↓ ogr2osm + translation script
OSM XML
  ↓ osmium
OSM PBF
  ↓ Routing service build
Routing

Example ogr2osm Translation Script¶

Save as swisstopo_wanderwege.py

Important notes:

objektart defines way type and width
stufe is NOT used for hiking difficulty

This script generates clean OSM tags, maps hiking difficulty, handles access and surface, and produces routing-compatible data:

def filter_tags(attrs):
    tags = {}

    # Base tags
    tags["highway"] = "path"
    tags["foot"] = "yes"
    tags["source"] = "swisstopo"

    # Name
    if attrs.get("name"):
        tags["name"] = attrs["name"]

    # Objektart → way type / width (use names, not IDs)
    objektart = str(attrs.get("objektart", "")).lower()

    if "1 m weg" in objektart:
        tags.update({"highway": "path", "width": "1"})
    elif "2 m weg" in objektart:
        tags.update({"highway": "path", "width": "2"})
    elif "markierte spur" in objektart:
        tags.update({"highway": "path", "trail_visibility": "good"})
    elif "klettersteig" in objektart:
        tags.update({
            "highway": "via_ferrata",
            "sac_scale": "demanding_alpine_hiking"
        })
    elif "fahrstrasse" in objektart or "strasse" in objektart:
        tags.update({"highway": "track"})

    # Wanderwege → sac_scale (authoritative)
    wanderwege = str(attrs.get("wanderwege", "")).lower()

    if "wanderweg" in wanderwege:
        tags["sac_scale"] = "hiking"
    elif "bergwanderweg" in wanderwege:
        tags["sac_scale"] = "mountain_hiking"
    elif "alpinwanderweg" in wanderwege:
        tags["sac_scale"] = "alpine_hiking"

    # Access / passability
    befahrbarkeit = str(attrs.get("befahrbarkeit", "")).lower()
    if befahrbarkeit in ("wahr", "true", "ja"):
        tags["access"] = "yes"
    elif befahrbarkeit in ("falsch", "false", "nein"):
        tags["access"] = "no"
    else:
        tags["access"] = "permissive"

    # Surface
    belag = str(attrs.get("belagsart", "")).lower()
    if "asphalt" in belag or "beton" in belag:
        tags["surface"] = "paved"
    elif "kies" in belag or "schotter" in belag:
        tags["surface"] = "gravel"
    elif "fels" in belag or "felsen" in belag:
        tags["surface"] = "rock"
    else:
        tags["surface"] = "ground"

    # Direction separation
    if str(attrs.get("richtungsgetrennt", "")).lower() in ("ja", "true", "1"):
        tags["oneway"] = "yes"

    return tags

Run the conversion¶

ogr2osm wanderwege.gpkg \
  -t swisstopo_wanderwege.py \
  -o wanderwege.osm

Convert to PBF:

osmium cat wanderwege.osm -o wanderwege.pbf

Data Sources & Access¶

Swisstopo Data Portal¶

swissTLM3D: Authoritative topographic landscape model
Download: swisstopo geoportal
License: Free for non-commercial use, requires registration

GTFS for Switzerland¶

SBB/CFF/FFS: opentransportdata.swiss
Regional providers: Various cantonal transport operators
Update frequency: Daily for major operators

Next Steps¶

Create GraphHopper and BRouter custom profiles
Add trail running bias for running-specific routing
Implement ski touring routing with winter-specific data
Integrate seasonal data updates (summer/winter trail networks)

WEP 4 Routing on External Data Sources¶