Abstract:
The West Hills Tunnel, located in Portland, Oregon, is a twin-bore, 4.8-km-long light rail transit tunnel that includes an underground station that is about 80 m deep. The ventilation requirements for the tunnel and the station were evaluated using the Subway Environment Simulation (SES) computer program. The results of the SES analysis were used to design a ventilation system and to develop predefined Environmental Control System (ECS) operating modes. The use of the ECS modes provides the fan and damper operations in their predefined positions for various fire scenarios. The ventilation-control system is unique in that it uses automatic platform-separation doors to create a safe refuge by isolating the incident platform during a station fire. The commissioning phase of the emergency ventilation system for the West Hills Tunnel is described. The ventilation system is designed to provide adequate ventilation during a vehicle fire of 19.3 MW. However, during commissioning, it is not practical to simulate a fire of this magnitude to confirm whether the ventilation system would actually prevent back layering of hot smoke. The application of the SES computer program was extended further to perform the cold-airflow analysis. The results of the cold-airflow analysis then were compared with the field-measured airflow to confirm that the ventilation system will provide adequate ventilation during a fire of the design size. The commissioning of the ventilation system also included extensive testing of ECS modes to confirm that fans, dampers, and automatic platform doors operate as required in each of the predefined operating modes. In addition to the tunnel and platform airflow measurements, cold-smoke tests were conducted in a few critical locations to demonstrate to the local fire officials the effectiveness of the ventilation system in controlling the spread of smoke. Fire-service personnel from the surrounding communities conducted several fire drills in the tunnel and on station platforms. Based on their experience with the fire drills, additional ventilation operating modes were added to support their plans for providing emergency responses.
Supplemental Notes:
This paper is available on the CD-ROM, Light Rail: Investment for the Future, 8th Joint Conference on Light Rail Transit.
