Skip to main content

Transportations Library

A comprehensive Rust-based library implementing transportation engineering methodologies (e.g. the Highway Capacity Manual (HCM)) with Python bindings.

Transportation engineering knowledge is siloed. The methods live in PDF manuals, agency spreadsheets, and closed desktop tools, and every consumer re-implements them, so the same HCM procedure yields different numbers in different shops with no way to trace which one follows the book. This library is the source-of-truth layer of the CrossTraffic stack. Each methodology is implemented once, with the equation or exhibit it implements cited at the definition, validated against the manual's published example problems, and released under a matched version line so the downstream surfaces (the Python bindings here, the WASM middleware, the MCP server, the web calculator) integrate one canonical computation instead of maintaining diverging copies. Data management concerns that usually stay implicit are handled explicitly. Edition differences are selectable rather than silently mixed, published errata are applied and documented, and the places where the manual is ambiguous or not reproducible from its printed procedure are recorded rather than papered over.

What this covers

Highway Capacity Manual 7th Edition computational chapters 10 through 24, with the supplemental chapters (25, 27, 28, 30, 31, 32, 33, 34, 35) they draw on:

Chapter Topic Chapter Topic
10 Freeway Facilities 18 Urban Street Segments
11 Freeway Reliability 19 Signalized Intersections
12 Basic Freeway and Multilane Segments 20 Two-Way STOP-Controlled Intersections
13 Freeway Weaving Segments 21 All-Way STOP-Controlled Intersections
14 Freeway Merge and Diverge Segments 22 Roundabouts
15 Two-Lane Highways 23 Ramp Terminals and Alternative Intersections
16 Urban Street Facilities 24 Off-Street Pedestrian and Bicycle Facilities
17 Urban Street Reliability

Methodologies are validated against the manual's own published example problems; see docs/hcm/procedures/ for per-chapter walkthroughs and docs/hcm/VERIFICATION.md for the places where the manual is ambiguous, self-contradictory, or not reproducible from its printed procedure.

Selecting an HCM edition

Edition 7.1 (November 2025) replaces Chapters 13, 14, 27, and 28 with new weaving, merge, and diverge methodologies. It does not supersede the rest of the manual, so the edition is selected per segment rather than globally, and defaults to the 7th Edition:

import json, transportations_library as tl

tl.hcm_versions()          # ["7", "7.1"]
tl.hcm_latest_version()    # "7.1"

seg = tl.WeavingSegment(version="7.1", length_short=1500.0, num_lanes=4, ffs=65.0,
                        v_ff=1815.0, v_fr=692.0, v_rf=1037.0, v_rr=1297.0,
                        phf=0.91, heavy_vehicle_pct=0.05,
                        lc_rf=0, lc_fr=1, nw_rf=2, nw_fr=1)
seg.run_analysis()                       # "C"
json.loads(seg.analysis_v7_1())["speed_avg"]   # 59.32 mi/h

The two editions are different models, not successive refinements: the same segment can land a full LOS letter apart between them. tl.hcm_version_changes_chapter("7.1", 19) returns False, because Edition 7.1 left Chapter 19 alone.

Installation

Prerequisites

  • Rust: Install from rustup.rs
  • Python: 3.10 or higher
  • UV: Modern Python package manager (recommended)

Using UV (Recommended)

# Clone the repository
git clone https://github.com/crosstraffic/transportations-library
cd transportations-library

# Create and activate virtual environment
uv venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate

# Install in development mode
uv pip install maturin pytest
maturin develop --release

Using pip

# Install dependencies
pip install maturin pytest

# Build and install
maturin develop --release

From PyPI

pip install transportations-library

Quick Start

For Two Lane Highways.

Python Usage

import transportations_library as tl

# Create a highway segment
segment = tl.Segment(
    passing_type=0,     # Passing Constrained
    length=1.5,         # 1.5 miles
    grade=2.0,          # 2% grade
    spl=55.0,           # 55 mph speed limit
    volume=800.0,       # 800 veh/hr
    phf=0.95,           # Peak hour factor
    phv=5.0             # 5% heavy vehicles
)

# Create highway facility
highway = tl.TwoLaneHighways([segment])

# Perform complete analysis
seg_num = 0
demand_flow, opposing_flow, capacity = highway.determine_demand_flow(seg_num)
ffs = highway.determine_free_flow_speed(seg_num)
avg_speed, _ = highway.estimate_average_speed(seg_num)
percent_followers = highway.estimate_percent_followers(seg_num)
follower_density = highway.determine_follower_density_pc_pz(seg_num)
# Exhibit 15-6 picks its threshold set by POSTED SPEED LIMIT, not average speed
los = highway.determine_segment_los(seg_num, highway.segments[seg_num].spl, capacity)

print(f"Level of Service: {los}")
print(f"Average Speed: {avg_speed:.1f} mph")
print(f"Follower Density: {follower_density:.1f} followers/mile")

Subsegment sections.

# Highway with horizontal curves
subsegments = [
    tl.SubSegment(length=2640.0, design_rad=800.0, sup_ele=4.0),  # Curved section
    tl.SubSegment(length=2640.0, design_rad=0.0, sup_ele=0.0)     # Tangent section
]

segment_with_curves = tl.Segment(
    passing_type=0, length=1.0, grade=3.0, spl=55.0,
    is_hc=True,  # Has horizontal curves
    subsegments=subsegments,
    volume=900.0, phf=0.92, phv=8.0
)

highway = tl.TwoLaneHighways([segment_with_curves])
# ... perform analysis

Parameter Constraints

The library exports all HCM/AASHTO parameter constraints as JSON, which can be used by validators and knowledge graphs:

import transportations_library as tl
import json

# Get all constraints
constraints = json.loads(tl.get_constraints())
print(f"Version: {constraints['version']}")

# Access specific constraint
lane_width = constraints['two_lane_highways']['lane_width']
print(f"Lane width: {lane_width['min']}-{lane_width['max']} {lane_width['unit']}")
print(f"Source: {lane_width['source']}")
# Output: Lane width: 9.0-12.0 ft
# Output: Source: HCM 7th Edition, Exhibit 15-8

# Validate inputs directly
errors = tl.validate_input(lane_width=8.0)  # Invalid - below 9 ft
print(errors)
# Output: ['lane_width = 8 ft is outside valid range [9, 12]. Source: HCM 7th Edition, Exhibit 15-8']

Available constraints include:

  • lane_width, shoulder_width (range)
  • passing_type, horizontal_class, vertical_class (enum)
  • grade, phf, phv, speed_limit (range)
  • speed_radius (table lookup - AASHTO Table 3-7)

Using from Rust, Python, and JavaScript

The same compute core is reachable from three languages, and the mapping is mechanical:

  • Rust is the source of truth. Every chapter lives under src/hcm/, and the structs there (BasicFreeways, WeavingSegment, RampSegment, ...) are the API. Add the crate as a dependency and call the run_analysis/step methods directly.
  • Python bindings are generated from the same structs via PyO3 (src/copython/), built with maturin. Field names, defaults, and units are identical to the Rust side; constructors take the struct fields as keyword arguments, and enums map to strings (version="7.1", terrain="level"). A Rust method returning Option<T> returns None in Python.
  • JavaScript goes through WebAssembly, but not from this repo: cross-traffic-middleware wraps these structs in wasm_bindgen types (WasmBasicFreeways, WasmRampSegment, ...) and is built with wasm-pack. The same Option<T> becomes undefined. The web calculator is the reference consumer.

One convention to know when porting numbers between languages: percentages are percent in the UI-facing bindings and decimals in Rust where the HCM equation wants a proportion; each binding's docstring states which it takes. Editions, LOS letters, and every published-example value are identical across the three surfaces, and the integration tests assert the Rust and Python sides against the same JSON fixtures in tests/ExampleCases/.

Testing

Run Tests

# Rust tests
cargo test

# Python tests
pytest tests/

# With coverage
pytest tests/ --cov=transportations_library

# Integration tests for chapter 15
cargo test --test chapter15_integration

Note: If you want to have changes in the Rust code to be reflected in Python, you need to run cargo clean and maturin develop again after making changes.

Example Test Cases

The library includes comprehensive test cases based on HCM examples:

  • Case 1: Basic passing constrained segment
  • Case 2: Segment with horizontal curves
  • Case 3: Multi-segment facility with different passing types
  • Case 4: Steep grade conditions with heavy vehicles

Development

Project Structure

transportations-library/
├── src/
│   ├── hcm/
│   │   ├── chapter15/           # Two-lane highways implementation
│   │   └── common.rs            # Shared HCM utilities
│   ├── copython/                # Python bindings
│   ├── utils.rs                 # Mathematical utilities
│   └── lib.rs                   # Library root
├── tests/                       # Integration tests
├── examples/                    # Usage examples
└── Cargo.toml                   # Rust configuration

Building from Source

# Development build
cargo build

# Release build
cargo build --release

# Build Python wheel
maturin build --release

# Development install with changes
cargo clean && maturin develop --release

Pipeline

The project uses GitHub Actions for CI/CD, including:

  • Running tests on push and pull requests
  • Building and publishing to Test PyPI on alpha releases
  • Building and publishing to Cargo and PyPI on new releases

To install a pre-release from Test PyPI, use (replace the version as needed):

pip install --no-cache-dir --verbose -i https://test.pypi.org/simple/ transportations-library==<version>

Versioning follows Semantic Versioning.

Also, you can find the latest alpha releases on Test PyPI.

Citation

If you use transportations-library or CrossTraffic in your research, please cite it as follows:

@software{tamaru2025tralib,
  title = {Transportations Library: Transportation knowledge management platform},
  author = {Tamaru, Rei},
  year = {2025},
  url = {https://github.com/crosstraffic/transportations-library},
  doi = {10.5281/zenodo.17295792},
}

You can also use the DOI to cite a specific version: DOI

Alternatively, you can find the citation information in the CITATION.cff file in this repository, which follows the Citation File Format standard.


Note: This library implements established transportation engineering methodologies for educational and professional use. Users should verify results and apply appropriate engineering judgment for real-world applications.

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

transportations_library-0.3.7.tar.gz (872.6 kB view details)

Uploaded Source

Built Distributions

If you're not sure about the file name format, learn more about wheel file names.

transportations_library-0.3.7-cp312-cp312-win_amd64.whl (1.1 MB view details)

Uploaded CPython 3.12Windows x86-64

transportations_library-0.3.7-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (1.2 MB view details)

Uploaded CPython 3.12manylinux: glibc 2.17+ x86-64

transportations_library-0.3.7-cp312-cp312-macosx_11_0_arm64.whl (1.1 MB view details)

Uploaded CPython 3.12macOS 11.0+ ARM64

transportations_library-0.3.7-cp311-cp311-win_amd64.whl (1.1 MB view details)

Uploaded CPython 3.11Windows x86-64

transportations_library-0.3.7-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (1.2 MB view details)

Uploaded CPython 3.11manylinux: glibc 2.17+ x86-64

transportations_library-0.3.7-cp311-cp311-macosx_11_0_arm64.whl (1.1 MB view details)

Uploaded CPython 3.11macOS 11.0+ ARM64

transportations_library-0.3.7-cp310-cp310-win_amd64.whl (1.1 MB view details)

Uploaded CPython 3.10Windows x86-64

transportations_library-0.3.7-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (1.2 MB view details)

Uploaded CPython 3.10manylinux: glibc 2.17+ x86-64

transportations_library-0.3.7-cp310-cp310-macosx_11_0_arm64.whl (1.1 MB view details)

Uploaded CPython 3.10macOS 11.0+ ARM64

File details

Details for the file transportations_library-0.3.7.tar.gz.

File metadata

  • Download URL: transportations_library-0.3.7.tar.gz
  • Upload date:
  • Size: 872.6 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? Yes
  • Uploaded via: twine/7.0.0 CPython/3.13.14

File hashes

Hashes for transportations_library-0.3.7.tar.gz
Algorithm Hash digest
SHA256 9340ad89b71ef97d0e3a0191d2919b4b9e576af42fb65c1408410b7af4717ec5
MD5 097488dbb5a53557205d7270bd548b11
BLAKE2b-256 499720d6c2d0e6ca89ba50d90a94096445830cbbb1396d5533d67f182177f613

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7.tar.gz:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp312-cp312-win_amd64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp312-cp312-win_amd64.whl
Algorithm Hash digest
SHA256 cb2d8c74a8b7c31d450d2a0aaa3a60ca76d64f5a4c382a5db48ac069a95caa7f
MD5 bf0fa44bbc329217ce97e4a402cfd085
BLAKE2b-256 1df1dfa0f66e6dfdb495165c759a69ae957a9b007ae93bd544c96d7595f20d76

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp312-cp312-win_amd64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Algorithm Hash digest
SHA256 5d5f1ff826fbadf520be7e9930903639ae9c456f9ab543f5bd7f32a7c9be4a1a
MD5 188f68d7d403481dd2fbdbb917763bf5
BLAKE2b-256 3b66c43d3e287afc323304ddcd2f91e4c59f1a7e7f61e4fdcdc44ba9c12e2f2d

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp312-cp312-macosx_11_0_arm64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp312-cp312-macosx_11_0_arm64.whl
Algorithm Hash digest
SHA256 5f32f8104dc567f06a6e5eeded1e738c28ac6f7ed9f67c22d52260db1f3803e2
MD5 d490d82d4de037a013b1f9710a082b6a
BLAKE2b-256 8db34baea99776028e6312eff88708ebd1cb33fb22e7624be7ab61287b714b05

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp312-cp312-macosx_11_0_arm64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp311-cp311-win_amd64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp311-cp311-win_amd64.whl
Algorithm Hash digest
SHA256 d285d6122c39c1f61da17eba458180dffaf95a764774baee9970c641701e551f
MD5 25651d61e5ec9bb8266833c0aa6c7e5b
BLAKE2b-256 7c2ecc96a521a8e1e69b6cd317ce087168893d47880bd17b646689de4b1179eb

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp311-cp311-win_amd64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Algorithm Hash digest
SHA256 a646c9198d91f5c3b5624aa1080388b6e81efe2dbbfaed7b6132d0ca52cdce11
MD5 7eda732c32795b07d756bb6355e5ea3d
BLAKE2b-256 27b36e9093980a5d51f0c241972d9defc260cbf157f3e4f42827e6a601ba91b6

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp311-cp311-macosx_11_0_arm64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp311-cp311-macosx_11_0_arm64.whl
Algorithm Hash digest
SHA256 597619ef712a1fc2d2f1a6bec0594de795d6975f5d6440453cdf8536ba891410
MD5 4b307e879b610f48edc071b4b7cc2c11
BLAKE2b-256 f9aa253c159531855bb3354e3ea3819d4683d700ec973f14a6aa1370e84615aa

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp311-cp311-macosx_11_0_arm64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp310-cp310-win_amd64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp310-cp310-win_amd64.whl
Algorithm Hash digest
SHA256 51c1261ca213b1f593b8c1053fd4825b183992f8d413863c8d7c6776da869b78
MD5 a91dbb0f0b568b633087e407197c7e98
BLAKE2b-256 2e3fdd66b5e7ecb8da214ea38ef9491c5f30a9a8b180b44ec8de409504f6046e

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp310-cp310-win_amd64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Algorithm Hash digest
SHA256 008728a17f40a5eb9fc14d9043985f48c4425f40446af12c7eed2b43d0671b47
MD5 9eb0ea91cbb83459b06bcb627c9bbd14
BLAKE2b-256 c07bd09b008112123c02bf84afe5ec5275b893a3e094199bcc12ef0310aa7e62

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

File details

Details for the file transportations_library-0.3.7-cp310-cp310-macosx_11_0_arm64.whl.

File metadata

File hashes

Hashes for transportations_library-0.3.7-cp310-cp310-macosx_11_0_arm64.whl
Algorithm Hash digest
SHA256 37b9aa5cc427273ab29cbe5b04bb0907b5dfbbff95893f2c09dc1c70a6168de8
MD5 5da7e48a34dc71eeeeecf2b5e68f4d0f
BLAKE2b-256 04d50986667a04ca6435422bf15b3e6231f66b05f47b1e9113ed038b6410af2e

See more details on using hashes here.

Provenance

The following attestation bundles were made for transportations_library-0.3.7-cp310-cp310-macosx_11_0_arm64.whl:

Publisher: release.yaml on crosstraffic/transportations-library

Attestations: Values shown here reflect the state when the release was signed and may no longer be current.

Release history Release notifications | RSS feed

This release

0.3.7 This release

10 files

0.3.6

10 files

0.3.5

10 files

0.3.4

10 files

0.3.3

10 files

0.3.2

10 files

0.3.1

10 files

0.3.0

10 files

0.2.0

10 files

0.1.12

2 files

0.1.11

10 files

0.1.10

12 files

0.1.8

4 files

0.1.7

4 files

0.1.6

4 files

0.1.5

4 files

0.1.4

1 file

0.1.3

3 files

0.1.2

3 files

0.1.1

2 files

0.1.0

2 files

Anthropic, PBC Visionary sponsor Bloomberg Visionary sponsor Hudson River Trading Visionary sponsor Meta Visionary sponsor NVIDIA Visionary sponsor Microsoft Sustainability sponsor Depot Continuous Integration AWS Cloud computing and Security Sponsor Datadog Monitoring Fastly CDN Google Download Analytics Sentry Error logging StatusPage Status page