MTA Pulse — Live NYC Transit Dashboard

## Overview

A full-stack SSR application running entirely on the Cloudflare Developer Platform. The MTA's GTFS-Realtime feeds provide arrival predictions — not GPS coordinates — so this app infers smooth geographic train positions by decoding binary protobuf payloads and interpolating each train's location along embedded track geometry polylines. The result is ~400-750 animated train positions updated every 15 seconds, rendered on an interactive MapLibre GL map with MTA-branded route lines, direction-coded train icons, and live service alerts.

## Highlights

• -> Full-stack SSR with TanStack Start deployed as a single Worker
• -> Binary protobuf GTFS-RT decoding with pure-ESM decoder (no Node.js APIs)
• -> Train position interpolation along real track polylines
• -> ~400-750 animated trains updated every 15 seconds at ~10fps
• -> Five Cloudflare bindings: KV, R2, D1, Workers AI, Observability

## Architecture

Browser (React + MapLibre GL)
    │   SSR hydration + 15s polling via server functions
    ▼
Cloudflare Worker (TanStack Start SSR)
    ├── Fetches 10 MTA GTFS-RT feeds in parallel
    ├── Decodes binary protobuf payloads
    ├── Interpolates train positions along track geometry
    ├── Workers KV ─── GTFS static data cache
    ├── D1 (SQLite) ── user preferences, saved routes
    ├── R2 ─────────── station photos, feed archival
    └── Workers AI ──── (planned) disruption summaries
    ▼
MTA GTFS-Realtime API (public, no key required)

## Tech Stack