Traffic Light Procedure (TLP)

Introduction: TLP

The Traffic Light Procedure (TLP) is a structured review method used in supplier collaboration and quality management. It offers a clear, visual approach to reviewing drawings, specifications, and processes step by step with suppliers, ensuring mutual understanding before production begins. By using simple colour coding, the TLP enables quick identification of issues and promotes open, fact-based discussions.

Background

The TLP was developed as a practical communication tool to enhance coordination between manufacturers and suppliers. In complex supply chains, unclear specifications, late feedback, and inconsistent expectations can lead to costly rework and delays. The TLP standardises the review process, ensuring that all technical and process requirements are fully discussed and agreed upon before production or approval. This method not only improves documentation and traceability but also strengthens partnerships through transparent collaboration.

Key Elements / Features

The Traffic Light Procedure is built around the familiar traffic light colour system:

• Green: Approved and acceptable as is; no further action required.
• Amber (Yellow): Needs clarification, additional data, or further investigation before approval.
• Red: Not acceptable; requires correction, redesign, or further development.

A typical TLP session involves reviewing each specification line by line, marking it with a colour, and recording amber and red items in a checklist or action matrix. Responsibilities, due dates, and follow-up actions are then assigned, ensuring accountability and closure.

Applications / Examples

The TLP is widely applied across engineering and supply chain processes, including:

• Supplier Quality Assurance: Reviewing technical drawings, control plans, and inspection criteria.
• New Product Introduction (NPI): Confirming supplier readiness and process capability before launch.
• Engineering Change Management: Verifying that design modifications are feasible and clearly understood.
• Lean and Six Sigma Projects: Supporting structured discussions and ensuring alignment during process improvement initiatives.

Relevance / Impact

The Traffic Light Procedure helps organisations prevent miscommunication and design errors by creating shared visibility of risks and decisions. It promotes early problem detection, strengthens supplier relationships, and builds a culture of proactive collaboration. In practice, TLP sessions often uncover hidden issues early in the process, saving time, reducing cost, and improving overall product quality.

See also

• Andon
• Jidoka
• Stop the Line
• Visual Management