How Engineers Turn Car Safety Goals into Tests

“The controller shall detect sensor faults” sounds like a good safety rule. But which faults? How quickly? What should the car do next?

Engineers need clearer answers before they can build or test a safe system.

Begin with the danger

ISO 26262 is a safety standard for road vehicles. It helps teams study possible dangers and decide what the vehicle must do to reduce the risk.

For example, imagine a faulty sensor tells an electric motor to produce too much power. Engineers first decide what safe behaviour looks like. The system might limit power, warn the driver or move into a safe state.

Only then should the team write detailed requirements for sensors, software and hardware.

Make each requirement testable

A strong safety requirement explains:

• what event starts the action;
• what response is required;
• how quickly it must happen;
• which part of the system is responsible;
• how the response will be tested.

Numbers should come from real safety analysis. Engineers should not invent a response time simply because it makes a sentence look precise.

Connect the whole story

A safety goal should connect to the detailed requirements, the design and the test evidence. These links are called traceability.

Traceability matters when something changes. If a sensor is replaced, the team can quickly see which requirements, safety arguments and tests may be affected.

The links do not prove a car is safe by themselves. Engineers still need to review the evidence and check that assumptions remain true.

Engineer-approved AI can flag unclear wording and broken links, while safety decisions stay with qualified engineers.