Abstract
"Japan Clean Air Program" (JCAP) is a research program for improving air quality in Japan. The program is conducted by Japan Petroleum Energy Center as a joint research program of automobile and petroleum industries. The Ministry of Economy, Trade and Industry also support it. JCAPⅡ, the second stage activity, is being conducted from FY2002 to FY2006.
Among various research works in JCAPⅡ, Roadside Air Quality Simulation Model (RsAQSM) has been developed. This model aims for detailed prediction of future atmospheric environment along urban arterial roads and for developing strategic plans to improve the environment. RsAQSM consists of three models: 1) microscopic traffic simulation model, which predicts detailed movement of vehicles in the target area, 2) transient emission estimation model, which calculates instantaneous vehicular emissions based on their movement, 3) Computational Fluid Dynamics (CFD) model, which predicts wind flow in the street canyon and emission advection/diffusion. In this paper, development and results of the microscopic traffic simulation model will be reported.
Amount and classification of the emissions greatly depend on traffic conditions. Also it depends on the movement of individual vehicle as well as the driving characteristics of each driver. And so, the authors have developed the microscopic traffic simulation model based on the movements and characteristics of vehicles for running the transient emission estimation model. In this model, efforts were made to incorporate the characteristics of Japanese drivers into Paramics, the microscopic traffic simulator. By using this model, quantitative comparison of the air quality became possible between the intersection and its background area.
The model was applied to the Kamiuma intersection and Noge intersection in Tokyo. Traffic simulations were performed by using collected data, so that various parameters in the model were optimised. Conventional evaluation parameters such as traffic flow and average vehicle velocity were evaluated and good reproducibility was obtained. In addition, a new microscopic evaluation parameter was evaluated, and reproducibility was also good. The new parameter was the ratio of time of driving mode. The driving modes are classified into four modes: stopping, acceleration, constant velocity running, and deceleration. As a simulation result, this model outputs the position, velocity, and acceleration data of each vehicle every second. The transient emission estimation model used these data to estimate emission concentrations on the roads. Besides, the estimated emission distribution data were input into CFD model to estimate the concentration field at roadside. And CFD model revealed that "hot-spots" exist at the intersection area.
Keywords: traffic simulation, vehicle emissions, roadside, air quality, Paramics