Opus AccuScan™ Remote Sensing Device (RSD) remotely measures exhaust emissions from motor vehicles as they are driven past the remote sensing device on streets and highways. The emissions are measured spectroscopically by casting a narrow infrared (IR) and ultraviolet (UV) beam of light across the road and through the trailing exhaust of passing motor vehicles. A mirror then reflects the IR/UV light back to a series of detectors that measure the amount of transmitted light at characteristic wavelengths absorbed by the pollutants of interest.

The RSD can measure the emissions emitted by the vehicles circulating under real-driving conditions. Since it takes only a second to capture a measurement, these devices can capture large quantities of vehicle emissions data in a short period of time. Also, since it is a non-intrusive technique, the RSD monitors the vehicles without interfering with the traffic flow.

In brief, the system measures the spectroscopic absorbance in infrared (IR) and ultraviolet (UV) light of: hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen monoxide and dioxide (NO and NO2 separately, combined as NOx), ammonia (NH3) and particulate matter as a proxy from opaccity (PM). By taking the ratios of the various pollutants to CO2 and applying stoichiometric rules and other conversion factors, the emission values can be epressed in meaningful units (i.e. g/kg fuel burned), which can then be converted to ravelled distance emissions (g/km) with appropriate assumptions.

Exhaust emissions are measured instantly, accurately and non-intrusively

What does the RSD measure?

The RSD measures the concentrations of Carbon Monoxide (CO), Hydrocarbons (HC), Oxides and Dioxides of Nitrogen (NO and NO2) and Particulate Matter (PM). The system shines beams of ultraviolet and infrared light across the road. The amount of specific wavelengths of light absorbed by the pollutant in the vehicle's exhaust and evaporative emissions is recorded and those readings enable us to determine the concentrations of pollutants present in the exhaust plme of the vehicle. The sensors detect emissions from tailpipe exhausts, as well as evaporative emissions caused by leaks from fuel lines, pumps, tanks and other components. The device also captures the licence plate of the vehicle and measures the vehicle's speed and acceleration at the time of the emissions' measurement. All of this completes a "record". The RSD detects and measures each vehicle as the vehicle drives by. The process of measuring emissions remotely begins when the vehicle breaks the invisible beam crossing the road. Each vehicle record consists of 100 measurements of the exhaust plume in 0,5 seconds. Exhaust emissions, speed, acceleration, ambient conditions, the license plate text and the time stamp are all recorded in less than a second. All that information relates to a vehicle record. That record is transferred by 4G/5G in real-time to our Remote Sensing Data Platform.

How effective is the RSD?

Our ISO-17025 accreditation gives us a remote measurement accuracy of 15%, similar to other road traffic measurement systems. Our accreditation allows us to ensure the accuracy, relative uncertainty and repeatability of our measurements. In addition, our system has a 90% correlation with PEMS and has been validated by multiple independent international bodies.

Typical portable setup

Key characteristics