gmns-ready 0.0.1

Tools for preparing and validating GMNS transportation network data

GMNS Ready

Professional toolkit for preparing and validating GMNS transportation networks with complete zone connectivity.

Overview

gmns-ready is a comprehensive Python package that prepares, validates, and enhances GMNS (General Modeling Network Specification) transportation networks. It automates the critical but often manual process of connecting traffic analysis zones to road networks, ensuring your data is ready for traffic assignment and travel demand modeling.

Key Capabilities:

• ✅ Validate spatial alignment before processing
• ✅ Extract and process zone data from shapefiles with automatic detection
• ✅ Generate zone-to-network connectors following Forward Star structure
• ✅ Validate network integrity and accessibility
• ✅ Enhance connectivity for zones with limited network access
• ✅ Prepare networks for traffic assignment with VDF parameter validation

Installation

pip install gmns-ready

Or install from source:

git clone https://github.com/hhhhhenanZ/gmns_ready.git
cd gmns_ready
pip install -e .

Quick Start

import gmns_ready as gr

# Step 1: Validate inputs are spatially aligned
gr.validate_basemap()

# Step 2: Extract zones from shapefile (auto-detects .shp in data/ folder)
gr.extract_zones()

# Step 3: Build zone-connected network
gr.build_network()

# Step 4: Validate everything
gr.validate_network()
gr.validate_accessibility()
gr.validate_assignment()

---

Core Functions

1. Input Validation

validate_basemap() - Verify spatial alignment of input files

Checks that node.csv, link.csv, and zone shapefiles are in the same geographic area before processing. This prevents common errors from misaligned data sources and saves troubleshooting time.

import gmns_ready as gr

gr.validate_basemap()  # Checks files in current directory

When to use: FIRST step before any processing

Inputs:

• node.csv and link.csv in current directory
• Any .shp file in data/ folder

Output: data/base_map_validation_report.json

What it checks:

• Coordinate system consistency
• Geographic overlap of all datasets
• Bounding box alignment

---

2. Zone Data Processing

extract_zones() - Extract zone centroids and boundaries from shapefile

Automatically detects and processes zone shapefiles (census tracts, TAZs, etc.) from the data/ folder. Calculates centroids, preserves boundaries, and generates GMNS-compliant zone.csv with automatic coordinate projection to EPSG:4326.

import gmns_ready as gr

gr.extract_zones()  # Auto-detects .shp file in data/ folder

Inputs:

• Any .shp file in data/ folder (auto-detected)
• Supports multiple shapefile types: census tracts, TAZ, custom zones

Outputs:

• zone.csv with zone_id, x_coord, y_coord, boundary_geometry (WKT)

Features:

• Auto-detects zone ID column (TRACTCE, GEOID, TAZ, etc.)
• Reprojects to EPSG:4326 automatically
• Preserves both centroid points and boundary polygons

---

extract_zones_pop() - Add population data to zones (US only)

Fetches and adds demographic data from ACS 2022 API for US zones. Outputs the same zone.csv with an additional population column.

import gmns_ready as gr

gr.extract_zones_pop()  # Uses .shp from data/, adds population column

Inputs:

• Any .shp file in data/ folder (auto-detected)

Outputs:

• zone.csv with all zone data + population column

Note: Only works for US locations. Population data does not affect network connectivity.

---

3. Network Building

build_network() - Generate zone-connected network with connectors

The core function that creates a complete zone-connected network following Forward Star Network Structure. Connects each zone to the nearest road network nodes and creates activity nodes for demand generation.

import gmns_ready as gr

gr.build_network()  # Uses zone.csv, node.csv, link.csv from current directory

Prerequisites:

• zone.csv from extract_zones()
• node.csv and link.csv from osm2gmns

Outputs: connected_network/ folder containing:

• node.csv - Network nodes + activity nodes + zone centroids
• link.csv - Road links + connector links
• activity_node.csv - Activity nodes (trip generation points)
• connector_links.csv - Connector links only

What it does:

• Connects each zone centroid to nearest network nodes
• Creates activity nodes from OSM POIs (residential, commercial, educational, transit locations)
• Ensures bidirectional connectivity between zones and network
• Maintains GMNS format compliance

Key concept: Activity nodes are OSM-derived points of interest that represent where trips begin or end in GMNS-based demand modeling.

---

4. Network Validation

validate_network() - Check network structure and topology

Validates network topology, node-link consistency, connectivity, and GMNS format compliance for the zone-connected network.

import gmns_ready as gr

gr.validate_network()  # Checks connected_network/ folder

Output: connected_network/network_validation_report.json

What it checks:

• Node-link topology consistency
• Network connectivity (all zones reachable)
• GMNS format compliance
• Data integrity

---

validate_accessibility() - Analyze zone-to-zone connectivity

Computes zone-to-zone accessibility matrix to identify connectivity issues and poorly connected zones.

import gmns_ready as gr

gr.validate_accessibility()  # Checks connected_network/ folder

Output: connected_network/accessibility_validation_report.json

What it computes:

• Zone-to-zone reachability matrix
• Origin/destination connectivity scores
• Identifies zones with poor accessibility (<10% of total zones)

Check results: Review the report to identify zones that may need additional connectors.

---

validate_assignment() - Verify traffic assignment readiness

Validates VDF (Volume-Delay Function) parameters and link attributes required for traffic assignment by link type.

import gmns_ready as gr

gr.validate_assignment()  # Checks connected_network/ folder

Output: connected_network/assignment_validation_summary.json

What it checks:

• VDF parameters: vdf_alpha, vdf_beta, vdf_plf, vdf_fftt
• Link capacity by link_type
• Parameter value ranges and consistency
• Excludes connectors (link_type=0) from validation

---

5. Connectivity Enhancement

enhance_connectors() - Add connectors for poorly connected zones

Adds 10 additional connectors per zone to improve accessibility for zones with poor network connectivity (<10% of total zones). Distributes connectors across road hierarchy: 3 to highways, 3 to arterials, 2 to collectors, 2 to local roads.

import gmns_ready as gr

gr.enhance_connectors()  # Enhances connected_network/ folder

When to use:

• After running validate_accessibility()
• When zones show low connectivity scores (<10% of total zones)
• To improve network coverage for isolated zones

Outputs:

• connected_network/link_updated.csv - Enhanced link file with additional connectors
• connected_network/connector_editor_report.txt - Detailed report of added connectors

Workflow:

1. Run enhance_connectors()
2. Review link_updated.csv and report
3. Replace connected_network/link.csv with link_updated.csv
4. Re-run validate_accessibility() to verify improvements
5. Repeat if needed until accessibility requirements are met

---

Network Preparation

clean_network() - Remove disconnected components from OSM networks

OSM networks extracted via osm2gmns may contain disconnected islands or isolated segments due to data quality issues. This function identifies the main connected component and removes isolated parts, ensuring your network is fully traversable.

import gmns_ready as gr

gr.clean_network()  # Cleans node.csv and link.csv from osm2gmns

When to use:

• BEFORE building zone-connected network
• After extracting network from osm2gmns
• When you suspect OSM data quality issues
• To ensure complete network traversability

Inputs:

• node.csv and link.csv (from osm2gmns in current directory)

Outputs: osm_network_connectivity_check/ folder containing:

• Cleaned node.csv and link.csv (main connected component only)
• network_connectivity_analysis.png - Before/after visualization
• isolated_components_detail.png - Detailed view of removed components

After running: Replace your original node.csv and link.csv with the cleaned versions from osm_network_connectivity_check/ folder, then proceed to build_network().

---

Complete Workflow Example

import gmns_ready as gr
import osm2gmns as og

# ============================================================================
# STEP 0: Generate base network from OSM (using osm2gmns)
# ============================================================================
# net = og.getNetFromFile('map.osm')
# og.outputNetToCSV(net)  # Creates node.csv and link.csv

# ============================================================================
# STEP 0.5: Clean OSM network (recommended)
# ============================================================================
gr.clean_network()
# Copy cleaned files from osm_network_connectivity_check/ to project root

# ============================================================================
# STEP 1: Validate spatial alignment
# ============================================================================
gr.validate_basemap()
# Check: data/base_map_validation_report.json

# ============================================================================
# STEP 2: Extract zones
# ============================================================================
gr.extract_zones()
# Output: zone.csv

# Optional: Add population data (US only)
# gr.extract_zones_pop()
# Output: zone.csv with population column

# ============================================================================
# STEP 3: Build zone-connected network
# ============================================================================
gr.build_network()
# Output: connected_network/ folder with all network files

# ============================================================================
# STEP 4: Validate network
# ============================================================================
gr.validate_network()
# Check: connected_network/network_validation_report.json

gr.validate_accessibility()
# Check: connected_network/accessibility_validation_report.json

gr.validate_assignment()
# Check: connected_network/assignment_validation_summary.json

# ============================================================================
# STEP 5: Enhance connectivity if needed
# ============================================================================
# If accessibility report shows poorly connected zones:
gr.enhance_connectors()
# Output: connected_network/link_updated.csv

# Replace link.csv with link_updated.csv
# import shutil
# shutil.copy('connected_network/link_updated.csv', 'connected_network/link.csv')

# Re-validate
gr.validate_accessibility()

# Repeat enhancement if needed until all zones meet requirements

---

Project Structure

your_project/
├── data/
│   ├── zones.shp                    # Input: Zone shapefile (any name)
│   └── base_map_validation_report.json
├── node.csv                         # From osm2gmns
├── link.csv                         # From osm2gmns
├── zone.csv                         # Generated by extract_zones()
├── osm_network_connectivity_check/  # Optional: cleaned network
│   ├── node.csv
│   ├── link.csv
│   ├── network_connectivity_analysis.png
│   └── isolated_components_detail.png
└── connected_network/               # Final output
    ├── node.csv
    ├── link.csv
    ├── activity_node.csv
    ├── connector_links.csv
    ├── network_validation_report.json
    ├── accessibility_validation_report.json
    ├── assignment_validation_summary.json
    ├── link_updated.csv             # If enhanced
    └── connector_editor_report.txt  # If enhanced

---

Function Reference

Import Style

# Recommended: Import once, use all functions
import gmns_ready as gr

# Then call any function:
gr.validate_basemap()
gr.extract_zones()
gr.build_network()
gr.validate_network()
gr.validate_accessibility()
gr.validate_assignment()
gr.enhance_connectors()
gr.extract_zones_pop()
gr.clean_network()

Function Summary

Function	Purpose	When to Use
validate_basemap()	Check spatial alignment	FIRST - before any processing
extract_zones()	Extract zones from shapefile	After basemap validation
extract_zones_pop()	Add population to zones	Optional, US only
build_network()	Create zone-connected network	After zone extraction
validate_network()	Check network structure	After network building
validate_accessibility()	Analyze zone connectivity	After network building
validate_assignment()	Check assignment readiness	After network building
enhance_connectors()	Add more connectors	When accessibility is poor
clean_network()	Remove isolated components	Before network building (optional)

---

Integration with osm2gmns

This package is designed to work seamlessly with osm2gmns for base network generation.

---

Requirements

python >= 3.7
pandas >= 1.3.0
geopandas >= 0.10.0
shapely >= 1.8.0
matplotlib >= 3.3.0
networkx >= 2.6.0

---

GMNS Compliance

This package follows the General Modeling Network Specification (GMNS) standard, ensuring compatibility with:

• Traffic assignment tools (e.g., TAPLite, DTALite)
• Travel demand models
• Network visualization tools
• Other GMNS-compliant software

---

Citation

If you use this package in your research, please cite:

@software{gmns_ready,
  author = {Zhu, Henan and Zhou, Xuesong and Zheng, Han},
  title  = {GMNS Ready: Professional Toolkit for GMNS Transportation Networks},
  year   = {2025},
  url    = {https://github.com/hhhhhenanZ/gmns_ready}
}

---

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details.

Authors

Henan Zhu, Xuesong Zhou, Han Zheng
Arizona State University

Contact:

• Issues: GitHub Issues
• Email: [e-mail], [e-mail]

Acknowledgments

• Zephyr Foundation for GMNS standards
• osm2gmns team for base network generation