Modeling of carbon monoxide dispersion around the urban tunnel portals

Mehdi Rafiei, Peter-Johann Sturm

Research output: Contribution to journalArticle

Abstract

ABSTRACT: The aim of this study is to investigate the problems caused by discharge of polluted air from
tunnels into the environment with a specific focus on residential areas. In city tunnels, portal or stacks,
pollutant management is a big challenge. Nowadays, air quality management, particularly in urban tunnels,
is considered as a part of the ventilation system design. The goal is to see the environmental impacts
beforehand. From environmental aspects, preventive measures are required either inside or outside the
tunnel in some cases. Niayesh tunnel in Tehran is taken as a case for proving the objectives presented in
this study. Concentration of carbon monoxide at the vicinity of the portals is calculated using the proper
dispersion simulation. The results of dispersion modeling for the assumed worst case of ventilation can
help to understand the environmental impact of ventilation. The worst traffic emissions for a congested
traffic scenario,are selected as an emission source for dispersion modeling. According to the traffic condition
and fleet composition, the crucial emission extracted from the tunnel is carbon monoxide. Therefore, the
performed simulation only focuses on carbon monoxide dispersion modeling. From the other side, carbon
monoxide is taken as a demonstration pollutant, because it is inert and chemical reactions can be neglected
in short-term considerations. A lagrangian model composed of Graz Lagrangian Model and Graz Mesoscale
Model is used for flow-field and dispersion calculations.
Original languageEnglish
Number of pages14
JournalGlobal Journal of Environmental Science and Management
Publication statusE-pub ahead of print - 1 Jul 2018

Keywords

  • Dispersion modelling
  • GRAL
  • Tunnel portals

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