# UmarTransit-1B: First Open-Source Transit Domain LLM (Fine-tuned Qwen2.5-1.5B)

> Source: <https://discuss.huggingface.co/t/umartransit-1b-first-open-source-transit-domain-llm-fine-tuned-qwen2-5-1-5b/177611#post_1>
> Published: 2026-07-09 07:06:46+00:00

Hi everyone!

I’m sharing **UmarTransit-1B** — a domain-specific language model fine-tuned for public transit systems and GTFS (General Transit Feed Specification) data.

A QLoRA fine-tuned version of Qwen2.5-1.5B-Instruct that specializes in GTFS specification knowledge, transit route/schedule analysis, stop/station information across 10 countries, and transfer connections.

**Available formats:**

I’m a Senior Technical Lead (Java/Spring Boot, 14+ years) experienced with LLM APIs (OpenAI, Claude) and GTFS/transit systems. This is my first end-to-end model training project — from data collection to fine-tuning to deployment. Built the entire pipeline:

Training: QLoRA rank=16, alpha=32, 3 epochs, ~30 min on Colab T4, Unsloth + TRL SFTTrainer

Q: What does route_type 3 mean in GTFS? A: In the GTFS specification, route_type 3 indicates Bus service. This is the most common route type and covers short- and long-distance bus routes.

Q: How many routes does the Chicago Transit Authority operate? A: The Chicago Transit Authority (CTA) operates 133 routes. 8 are Subway/Metro routes and 125 are Bus routes.

Q: Can GTFS times exceed 24:00:00? A: Yes, GTFS allows times greater than 24:00:00 in stop_times.txt. This is used for trips that extend past midnight relative to the service day.

The entire project is open source (Apache 2.0) with a detailed build guide for engineers new to AI/ML. Feedback and contributions welcome!