sl-transit-tracker — Sri Lanka Transit Operations Center

A production-grade, full-stack transit operations and simulation platform designed to unify fragmented Sri Lankan intercity bus data. This project demonstrates advanced patterns in modern web development, including distance-based linear interpolation for real-time tracking, sophisticated overtake computation, and enterprise-grade API documentation.

What This Project Demonstrates

• Modern Frontend: React 18 + Vite with role-aware operations layouts, high-fidelity transit dashboards, and interactive Leaflet maps.
• Robust Backend: Node.js/Express API with a high-performance structured JSON data layer and specialized transit computation utilities.
• Advanced Simulation: A custom-built km-based linear interpolation engine for detecting vehicle overtakes and predicting real-time asset positions.
• API Governance: Complete OpenAPI 3.0 (Swagger) integration for standardized endpoint management and interactive documentation.
• Performance Analytics: Multi-layered data visualization comparing Scheduled vs. Actual journey metrics using Chart.js time-space diagrams.
• Cloud Native: Architecture optimized for automated deployment via platforms like Vercel (frontend) and Render (backend).

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Core Features

1. Operations and Live Simulation

• Live Asset Tracking: Visualizes bus positions on an interactive Leaflet map using real-time interpolation along route corridors.
• Overtake Simulation Engine: pure-function computation that detects pairwise vehicle interactions across 1km sampled corridor intervals.
• Interactive Time-Space Diagrams: Visualizes the entire route lifecycle, allowing operators to see scheduled paths vs. real-world deviations.

2. Transit Performance Analytics

• Scheduled vs. Actual Tracking: Seamless integration of recorded journey data with optimistic UI overlays for instant delay analysis.
• Delay Segment Profiling: Identifies specific road segments where time was lost (e.g., "Heavy traffic after Puttalam") using dashed overlay line-markers on charts.
• Timetable Intelligence: Instant access to searchable intercity timetables across multiple vehicle classes (Luxury, Semi-Luxury, etc.).

3. API Governance & Security

• Standardized Documentation: Fully managed OpenAPI 3.0 specs available via the /api-docs Swagger portal.
• Modular API Architecture: Versioned-ready endpoints for routes, fleet journeys, and overtake calculations.
• Security & Hardening: Implemented CORS policies and standardized error handling across the Express middleware stack.

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Tech Stack

Frontend

• Framework: React 18 (Vite)
• Styling: Tailwind CSS
• Visualizations: Chart.js (Time-Space Diagrams), React-Leaflet (GIS)
• Routing: React Router DOM

Backend

• Runtime: Node.js, Express
• Data Layer: Structured JSON (Flat-file Corridor DB)
• Documentation: Swagger UI, YAML
• Utilities: Custom Linear Interpolation Engine

Deployment & Infrastructure

• Cloud Platforms: Vercel, Render
• CI/CD: Optimized for GitHub Actions / Automated cloud deployments

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System Architecture

graph TD
    Data[JSON Corridor Data] -->|Route & Stop Specs| BE[Node.js/Express API]
    BE -->|Overtake Compute| Util[Interpolation Engine]
    Util --> BE
    BE -->|REST API| FE[React Operations UI]
    FE -->|Chart.js| Plot[Time-Space Diagram]
    FE -->|Leaflet| Map[Map Visualization]
    FE -->|Tailwind| UI[Command Center Interface]

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Local Setup

1. Backend

cd backend
npm install
npm run dev

API runs at http://localhost:4000. Swagger docs at /api-docs.

2. Frontend

cd frontend
npm install
npm run dev

UI runs at http://localhost:5173.

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Future Roadmap

• IoT Integration: WebSocket-based real-time GPS telemetry for live bus positions.
• AI Forecasting: Predictive delay analysis using historical traffic patterns.
• Multi-Corridor Expansion: Scaling to Kandy, Galle, and Matara transit lines.
• Passenger Companion: Mobile-first PWA for crowdsourced delay updates.

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Developed with ❤️ by Branavan