Traffic Management System

A MERN stack application that monitors traffic conditions and controls traffic signals in real time. The system uses live density data to adjust signal timings for smoother traffic flow.

Features

• Real-time monitoring – Dashboard shows traffic density and signal state per intersection
• Adaptive signals – Green duration is computed from traffic density (10–90 seconds)
• Per-lane density – North, South, East, West lanes with editable density and vehicle count
• Traffic logs – Historical snapshots of density and signal state
• WebSocket updates – Signal changes pushed to the UI without refresh

Tech Stack

• MongoDB – Intersections, lanes, traffic logs
• Express – REST API and Socket.io server
• React – Dashboard, intersections, logs (Vite)
• Node.js – Backend runtime

Prerequisites

• Node.js 18+
• MongoDB (local or Atlas)

Database setup (do this before running the backend)

Choose one option: local MongoDB or MongoDB Atlas (cloud).

Option A: MongoDB on your computer (local)

1. Install MongoDB

   • Windows: Download from mongodb.com/try/download/community and run the installer, or use Chocolatey: choco install mongodb
   • macOS: brew install mongodb-community then brew services start mongodb-community
   • Linux: Use your package manager (e.g. sudo apt install mongodb on Ubuntu)

2. Start MongoDB

   • Windows: If installed as a service, it may start automatically. Otherwise run mongod from the install directory (e.g. C:\Program Files\MongoDB\Server\7.0\bin\mongod.exe).
   • macOS/Linux: mongod (or sudo systemctl start mongod if using systemd).

3. Create the .env file in the backend folder (if you haven’t):

   cd backend
   cp .env.example .env

   The default MONGODB_URI=mongodb://localhost:27017/traffic_management is correct for local MongoDB. The database name traffic_management and the collections will be created automatically when the app runs.

Option B: MongoDB Atlas (cloud, no local install)

1. Go to mongodb.com/cloud/atlas and create a free account.
2. Create a free cluster (e.g. M0).
3. Create a database user: Security → Database Access → Add New User (username + password). Remember the password.
4. Allow network access: Security → Network Access → Add IP Address → allow 0.0.0.0 (or your IP) so your app can connect.
5. Get the connection string: Database → Connect → “Connect your application”. Copy the URI; it looks like:

   mongodb+srv://<username>:<password>@cluster0.xxxxx.mongodb.net/?retryWrites=true&w=majority
   

6. In the URI, replace <username> and <password> with your DB user. Add the database name before ?:

   mongodb+srv://myuser:mypass@cluster0.xxxxx.mongodb.net/traffic_management?retryWrites=true&w=majority
   

7. In the backend folder, create or edit .env and set:

   MONGODB_URI=mongodb+srv://myuser:mypass@cluster0.xxxxx.mongodb.net/traffic_management?retryWrites=true&w=majority
   

   (Use your real URI; special characters in the password must be URL-encoded.)

No need to create the database or collections manually. The app creates the traffic_management database and the intersections and trafficlogs collections when it runs.

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Setup

1. Backend

cd backend
npm install
cp .env.example .env

Edit backend/.env:

• MONGODB_URI – Local: mongodb://localhost:27017/traffic_management (default). Atlas: paste your connection string from Database setup above.
• PORT – default 5000
• CLIENT_URL – default http://localhost:5173

Seed sample intersections (optional, after backend can connect):

cd backend
npm run seed

Start the backend server (required; the frontend proxies API to this):

npm run dev

You should see Server running on http://localhost:5000. Keep this terminal open.

2. Frontend

cd frontend
npm install

Start the dev server (proxies API and Socket.io to backend):

npm run dev

Open http://localhost:5173.

Important: Run both backend and frontend:

• Terminal 1: cd backend → npm run dev (API on port 5000)
• Terminal 2: cd frontend → npm run dev (app on port 5173)

If MongoDB is not running, start it (e.g. mongod) or use a cloud URI in .env. The backend will still listen; API calls will fail until MongoDB is connected.

Troubleshooting

ECONNREFUSED or "http proxy error: /api/..."

The backend is not running. The frontend proxies /api to http://localhost:5000.

1. Open a second terminal.
2. Run: cd backend then npm run dev.
3. Ensure you see Server running on http://localhost:5000.
4. Reload the frontend; the proxy errors should stop.

MongoDB connection failed

Start MongoDB locally (mongod) or set MONGODB_URI in backend/.env to a valid URI (e.g. MongoDB Atlas). The backend stays up; fix the DB and retry.

Usage

1. Dashboard – View all intersections, current signal, and density. Edit density/vehicles per lane to simulate traffic; adaptive logic updates green duration.
2. Intersections – Add/delete intersections. Each has 4 directions with density bars and inline edit.
3. Traffic Logs – Filter by intersection and see past density/signal snapshots.

API Overview

Method	Endpoint	Description
GET	/api/intersections	List intersections
GET	/api/intersections/:id	Get one intersection
POST	/api/intersections	Create intersection
PUT	/api/intersections/:id	Update intersection
DELETE	/api/intersections/:id	Delete intersection
PATCH	/api/intersections/:id/density	Update lane density (body: { laneUpdates })
PATCH	/api/intersections/:id/signal	Set active signal and state
GET	/api/intersections/logs	Traffic logs (query: intersectionId, limit)

Real-time: Socket.io emits signal-update when any intersection’s signal state changes.

Project Structure

Traffic Management/
├── backend/
│   ├── config/db.js
│   ├── controllers/intersectionController.js
│   ├── models/Intersection.js, TrafficLog.js
│   ├── routes/intersectionRoutes.js
│   ├── utils/trafficLogic.js
│   ├── scripts/seed.js
│   └── server.js
├── frontend/
│   ├── src/
│   │   ├── api/api.js
│   │   ├── context/SocketContext.jsx
│   │   ├── components/
│   │   ├── pages/
│   │   └── App.jsx, main.jsx
│   └── vite.config.js
└── README.md

License

MIT