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Mountain Line (MUTD)

Mountain Line is the Missoula Urban Transportation District (MUTD), the public transit agency serving Missoula, Montana. Mountain Line operates 29 fixed-route buses and 17 paratransit vehicles, has been fare-free since January 2015, and runs a near-fully-electric fleet. It was named the 2025 CTAA Small Urban Agency of the Year and the 2021 APTA Outstanding Public Transportation System (top system under 4 million trips in North America).

This subfolder is Mountain Line’s entry in tides-implementations. Its primary purpose is to point to the open-source TIDES tooling being developed for Mountain Line’s data pipeline, so that other small and mid-sized agencies can fork, adapt, or learn from it.

Who to contact

Garin Wally — Transit Analyst, Mountain Line gwally@mountainline.com · GitHub: @WindfallLabs

What’s being implemented

Mountain Line is building a Python-based “analyst on a laptop” implementation pattern for TIDES — Level 0 in the TIDES Common Architecture Framework. The work in progress includes:

  • NTD reporting pipeline. Co-designed with MobilityData as the small-urban anchor of a multi-agency NTD reporting pilot framework (alongside WMATA’s large-agency pilot). The framework runs TIDES-derived NTD metrics in parallel with existing reporting for FY2027, with phased coverage of fixed-route monthly metrics, demand-response metrics, and full annual rollup.
  • Open-source schema validation library. polar-tides — a Python library for validating Polars DataFrames against TIDES table schemas, built on dataframely. All TIDES tables covered as dataframely.Schema classes with column types, nullability constraints, and value-enforcement rules for enum fields. Released as alpha (v0.1.0a1) under the MIT License.
  • Open-source orchestration library. little_pipelines — a minimal-dependency Python library for building and executing data pipelines. Decorator-based task definitions with automatic dependency resolution via graphlib.TopologicalSorter. Targets the analyst-on-a-laptop end of the spectrum, intentionally distinct from enterprise tools (Airflow, Prefect, Dagster, dbt). MIT-licensed.

Data sources being integrated

Source Vendor / system TIDES tables fed
CAD/AVL ETA Transit (replacing Clever) vehicle_locations, trips_performed
APC Hardware on every fixed-route bus, statistically processed by Swiftly passenger_events, stop_visits
Demand-response Via Transportation (Ride the Line — Missoula) trips_performed, derived DR metrics
Maintenance / fleet RTA (Ron Turley Associates) supporting reference data
Schedule Self-published GTFS / GTFS-RT linkage via trip_id_scheduled, stop_id

What’s published here (and what’s not)

This subfolder is currently a pointer entry. The active development happens in the linked external repositories above; Mountain Line’s working code lives there rather than being copied into this repo. As the implementation matures, additional materials may be added here directly — sample pipeline configurations, transformation worked examples, a case study writeup, or contributions of MUTD-specific reference data once it’s appropriate to share publicly.

If you’re an analyst at a small or mid-sized agency exploring TIDES, the polar-tides and little_pipelines repos linked above are the most useful starting points. Both are MIT-licensed and intentionally minimal in their dependencies.

License

Copyright 2026 Missoula Urban Transportation District

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

1
http://www.apache.org/licenses/LICENSE-2.0

Note that the linked external libraries (polar-tides, little_pipelines) are licensed independently by their author under the MIT License. Apache 2.0 and MIT are both permissive licenses and are fully compatible.