Vehicle emissions measurement and modeling

Abstract This chapter introduces conventional emissions monitoring and modeling practices used in the on-road transportation sector. It describes both laboratory-based dynamometer and real-world emissions monitoring practices including portable emissions measurement systems (PEMS) and vehicle emissions remote sensing systems (VERSS) and identifies key events that helped to shape conventional practices. It also describes commonly used macro, meso, and microscale emissions modeling methods and the changing nature of the relationship between monitoring and modeling activities. Finally, it considers concerns regarding the effectiveness of existing practices to support ongoing efforts to reduced vehicle fleet emissions, and opportunities to do better in future.