trelay - Railway Journey Analysis Platform

Architecture Overview

Frontend - React 19 Backend - Python & FastAPI Database - SQLite (caching) AI Integration - OpenAI GPT

Background:

I was motivated to build this tool after experiencing frequent train delays without having access
to historical performance data to plan journeys better. Existing platforms like National Rail show
live updates but lack comprehensive historical analysis, making it difficult to choose optimal
travel times.

This project integrates with the UK Historical Service Performance (HSP) API to fetch delay data
across any route, then visualizes departure and arrival performance through interactive histograms. The AI component (OpenAI) provides travel recommendations based on the statistical
patterns.

Key features include intelligent caching to avoid repeated API calls, station code autocomplete
for all UK stations, and streaming progress updates for long-running analyses. The histogram breakdown shows on-time rates, early arrivals, and various delay buckets to help commuters make
informed decisions.

View Source Code