Using On-Board Diagnostic Data to Model Heavy-Duty Vehicle Emissions

The California Air Resources Board wanted to better characterize and model emissions from on-road heavy-duty diesel vehicles. CARB contracted with ERG to provide this information. To characterize and model HDDV emissions, the ERG project team collected and analyzed HDDV onboard diagnostic data records from nearly 200,000 trucks scanned in a field study and compiled from a large telematics provider. They then analyzed the data to determine the rate of emissions-related malfunctions, the types of malfunctions and their prevalence, and the emissions impact of each malfunction type, grouped into CARB’s on-road emissions model categories. The resulting data will allow CARB to estimate emissions more accurately from late-mode HDDVs as they age, taking into account deterioration of modern emissions control technologies on these vehicles.