The Highways Agency and the NASS Project

The UK Highways Agency (HA) developed the Network ATM Supervisory Subsystem (NASS) to reduce congestion by controlling traffic based on actual and predicted road conditions. NASS was developed following the International Electrotechnical Commission’s IEC 61508 standard to ensure its safety. The system underwent several phases, including a proof-of-concept and production of a demonstrator system, before being integrated into the HA’s West Midlands Regional Control Centre.

This case study explores the testing strategy, code design, and module testing procedures used to validate the system’s effectiveness.