Case Study of Nanjing Inner Ring on Air Pollution Dispersion from Roadway Tunnel Portals

Abstract

The tunnel module of a rather simple Lagrangian model GRAL (Grazer Langrange model) has been chosen to study air pollutant dispersion around tunnel portals in Nanjing inner ring. Two points have been made to popularize GRAL3.5TM (the tunnel module of a Lagrangian model GRAL; the update was in May 2003) and assure it more suitable for the actual situations in Nanjing. One is to derive a piecewise function of the intermediate parameter ‘stiffness’. Another is to take Romberg NOx-NO2 scheme into account. After these 2 works on GRAL3.5TM, NO2 dispersion from portals of all the 6 tunnels in Nanjing inner ring has been simulated. The importance of limiting urban traffic volume to control air quality around tunnel portals and roadways has been emphasized.

Numerical Research on the Mixture Mechanism of Polluted and Fresh Air at the Staggered Tunnel Portals

“…In recent years, due to being restricted by landforms and architectural patterns, more and more twin tunnels with small spacing are being constructed [9,10]. During the operation of this kind of tunnel, not only do the pollutants of the outlet tunnel influence the local environment of the tunnel exit [11], but the pollutants also mix with new incoming air at the adjacent inlet to form circulating air, consequently intensifying the pollution level at the internal environment of the inlet tunnel and resulting in increasing costs of ventilation system construction and operation.…”