Tunnel Ventilation Systems Harmonization for Optimization of Tunnel Construction

摘要

The SR 99 Tunnel Ventilation System (TVS) manages pollutants, providing a safe and tenable environment for motorists in the tunnel during flowing traffic, stopped traffic, and congested traffic. The TVS also mitigates the effects of smoke and heat during a fire incident to facilitate evacuation of tunnel occupants and implementation of firefighting operations. Three subsystems key to the ability of the TVS are: the extraction ventilation system; the maintenance air ventilation system; and the jet fan ventilation system. The extraction ventilation system is made up of four centrifugal extraction fans in each of the two Tunnel Operations Buildings. The fans connect to a continuous extraction duct running along the east side of the tunnel. The fans pull smoke and pollutants out of the tunnel roadway through the extraction duct and exhaust it out of stacks on top of the buildings. All eight fans are available for smoke extraction. The maintenance air ventilation system is made up of one centrifugal fan and one backup fan in each of the two Tunnel Operations Buildings. These fans connect to a maintenance air duct running along the west side of the tunnel and a utilidor under the roadways. The maintenance air system pressurizes the egress passage, preventing smoke and pollutant infiltration from the roadways. The jet fan ventilation system consists of several jet fans mounted above and alongside the roadways near the tunnel portals. These fans manage the longitudinal airflow drawing fresh air into the roadway tunnel, and pushing smoke and heat out of the tunnel away from motorists. Design development of these three ventilation subsystems establish harmonized operation modes for managing the tunnel environment such that tunnel bore and approach cut and cover size was optimized.