Why these tiny devices under number plates matter more than you think

Ever noticed those little devices tucked beneath number plates on some cars during your morning commute? They quietly display speeds as traffic flows past, yet their purpose remained a mystery for many Australian drivers. A Melbourne commuter recently uncovered what they actually do—and it’s far more interesting than a simple speed readout.

Victoria has introduced extra measures to ensure road safety cameras are accurate and reliable, including independent infrared systems to verify the speeds they record. That curious device under the number plate acts as a mobile speed laboratory, constantly cross-checking camera readings against independently measured speeds. When you see the digital display showing passing vehicles’ speeds, you are witnessing quality control in action.

Camera recordings are tested against independent devices calibrated to a traceable national standard.

SGS, the company behind these testing vehicles, is no ordinary contractor. With over a century of experience in inspection, testing and certification services, SGS is the world’s leading Testing, Inspection and Certification company. This expertise reassures drivers that speed enforcement technology is accurate and reliable.

The testing process is more thorough than many realise. New cameras undergo strict Site Acceptance Testing before activation, covering physical, electrical, hardware, software, administrative and image assessments. Certification testing is then performed annually, and each camera unit is sealed to prevent unauthorised interference.

For many older drivers, road safety cameras can feel like a sudden and unwelcome change. Victoria’s rigorous testing system provides reassurance that enforcement is fair and precise. Each fixed digital camera is tested annually by an independent officer and, once approved, receives a certificate of compliance confirming it meets regulations.

Transparency is a key part of this system. Annual test certificates are publicly available, allowing anyone to verify whether a camera was properly tested at the time of a recorded offence.

Victoria’s testing approach stands out nationally. While NSW inspects camera recording devices every 90 days and speed-measuring devices at least every 12 months, Victoria combines annual comprehensive testing with continuous verification from independent systems like SGS vehicles, adding an extra layer of accuracy. Other mainland states and the ACT use average speed cameras for heavy and light vehicles, but Victoria’s multi-layered testing is particularly thorough.

Accuracy in enforcement contributes to broader road safety goals. Evidence shows camera enforcement reduces crashes, injuries and fatalities. In 25 regional locations with average speed cameras, deaths from crashes involving heavy vehicles fell by 44 per cent. For drivers used to when speed limits were more of a guideline, understanding modern enforcement as a combination of advanced technology and rigorous testing helps explain today’s systematic approach to road safety.

Next time you spot one of these speed-displaying vehicles, you are seeing a sophisticated quality assurance system in action—technology ensuring fairness for every driver.

While Victoria’s rigorous speed camera testing ensures fairness on the roads, technology can sometimes catch drivers in unexpected ways.

One striking example involves a hidden feature that captured drivers’ faces, leading to substantial fines despite many being unaware of it.

For a closer look at how this kind of real-world enforcement plays out, check out the following story.

Have you ever noticed one of these testing vehicles or checked a camera’s test certificate in your area?