RoadBond: Holding Road Contractors Accountable, On the Blockchain

RoadBond is a student project that makes road contractors pay for bad roads. When a contractor builds or repairs a road, the government usually keeps back a small part of the payment, called retention money, for a set period called the warranty (or Defect Liability Period). If potholes appear during that time, the contractor is supposed to fix them. In practice this often does not happen, and the public pays for the repairs instead.

RoadBond fixes this in three ways. First, the contract details are recorded on a blockchain. A blockchain is a shared record that many computers keep copies of, so no single person can quietly change it. The details include the road section, the contractor, the warranty end date and the retention amount. Second, the retention money is locked in a smart contract, a program that holds the money and follows fixed rules. This is called escrow. An official cannot take the money out. Third, the rules are written in code. If a citizen reports a pothole and several independent people confirm it, a repair deadline starts. If the contractor misses the deadline, the penalty is taken from the escrow automatically.

Citizens report a defect with a photo and a GPS location. The system checks whether that spot is on a registered road that is still under warranty. A repair needs approval from independent verifiers. A contractor who disagrees with a report can raise a dispute, which pauses the clock until an arbitrator decides. When the warranty ends with nothing left open, the remaining money is released to the contractor. Each contractor's record of defects, repairs and penalties stays public, so anyone can check it.

RoadBond is a prototype. It runs on a test blockchain on one computer, uses fake money and sample roads in Pune, India, and shows how the system would work. It is not a live government system.

1. Install Node.js 22 or newer.
2. Open a terminal in the project folder and run: npm run setup (once only)
3. Terminal 1: start the local blockchain with: npm run node (keep it running)
4. Terminal 2: start the photo and map server with: npm run backend
5. Terminal 3: load the demo contracts and roads with: npm run seed
6. Terminal 4: start the website with: npm run frontend
7. Open http://127.0.0.1:5173 in your browser. The map needs an internet connection.
8. In the top bar, choose "Demo accounts" and pick a citizen.
9. Open the Report tab, click near a road on the map, use the demo photo and submit.
10. Open the Defects tab. Confirm the defect with two other citizens, or with one verifier.
11. Use the "+7d" demo clock button to pass the repair deadline. Then press "Apply penalty".
12. Switch to the contractor account. Claim the repair with a photo. Then approve it with two verifiers.
13. Open the Contracts tab to see the escrow balance. After the warranty ends, release the retention.
14. To start again, stop the blockchain (npm run node), restart it, and run npm run seed.

Node.js 22 or newer (tested on Node 24)
npm (installed with Node.js)
A modern web browser such as Chrome
Internet connection (for map tiles from OpenStreetMap)
Optional: MetaMask browser extension, for wallet mode
Optional: a YOLOv8 pothole model in ONNX format for the AI hint (not included in the project)