Derivation of remote sensing cut points for the screening of high-emitting vehicles

Remote sensing devices (RSDs) are considered supplementary tools to enhance existing inspection and maintenance (I/M) programs. Emission compliance is determined by comparing the concentration of pollutants measured by an RSD to on-road remote sensing (RS) emission standards. The literature shows that RS emission standards are insensitive to vehicle speed and acceleration levels even though vehicle emissions are highly affected by the engine load. Consequently, this study firstly proposes a procedure for constructing on-road remote-sensing emission standards that are sensitive to vehicle speed and acceleration levels using the VT-Micro models and the Comprehensive Modal Emission Models (CMEMs). Given the proposed remote-sensing cut points, a comparison to the existing cut points is presented as well as sample tests. The results of the sample tests demonstrate that the approach is effective for HE (high-emitting) 3 and 4 vehicles of the VT-Micro emission models and requires further enhancements for HE-1 and -2 vehicles.