Development of a Roadside Air Quality Simulation Model in JCAP II

A Roadside Air Quality Simulation Model (RsAQSM) was developed in Phase II of the Japan Clean Air Program (JCAP II) for use in analyzing and studying strategies to address roadside air quality problems along main roads in urban areas. RsAQSM consists of (1) a micro-scale traffic model, (2) a transient emission estimation model, and a (3) wind and advection/diffusion model. Paramics was used to simulate the transient behavior of vehicles on roads in sub-model (1). Transient vehicular emissions were estimated using a newly developed transient emission database and methodology in sub-model (2). In sub-model (3), Star-CD was used to simulate wind flow and advection/diffusion of emissions, using a calculation mesh representing the detailed shapes of structures such as buildings or elevated roads and micro-scale topography along the roads. Each sub-model was validated in a real-world situation. Finally, a comparison with measurements made at air quality monitoring stations showed the validity and applicability of RsAQSM to real urban roadside areas.