TR Circular E-C058_9th LRT Conference_2003.pdf - Florida ...

400 Transportation Research Circular E-C058: 9th National Light Rail Transit Conference
ENVIRONMENTAL CONTROL SYSTEMS
The Environmental Control System (ECS) includes the following major subsystems:
1. Tunnel Ventilation
2. Platform Ventilation
3. Stairwell Pressurization
4. Elevator Shaft Pressurization
5. Ancillary Space Heating and Ventilation (and cooling where required)
6. Comfort Heating and Air Conditioning
Functional Requirements
The ECS for the Bergenline Avenue Station and the adjacent tunnel sections is designed to
provide ventilation during normal train operations and to support life safety operations during an
emergency caused by a fire or a vehicle derailment.
For the Bergenline Avenue Station support facilities, the ECS is designed to control
temperature and provide ventilation in electrical and mechanical rooms; and other ancillary
spaces to support routine maintenance and prolong the equipment life by controlling the room
temperature and humidity.
Tunnel Ventilation System
The tunnel ventilation system is designed to meet the emergency situation objectives. The
primary relevant fire emergencies include fire and smoke on the station platforms, in tunnel
sections or on board a train. In any of these situations the function of the tunnel ventilation
system is to maintain a relatively safe path of egress in case it becomes necessary to evacuate the
passengers. The platform and tunnel ventilation systems work in unison during an emergency.
Together they will develop airflow patterns to assist in the emergency rescue and fire fighting
personnel in gaining access to the fire scene.
For achieving these objectives, the platform and tunnel ventilation fans are operated such
that they provide a source of fresh air into the evacuation path and keep smoke and heat away
from the stranded passengers by exhausting air from the downstream side of the fire. Since the
direction of emergency evacuation depends on the location of fire, both the tunnel and platform
ventilation systems are designed with the capability of moving air in either direction.
The fire location, location of other vehicles in the tunnel, and passenger evacuation
direction are the three factors that affect the required number of fans and their operating modes.
The airflow capacities of the tunnel and platform ventilation systems were evaluated using the
Subway Environment Simulation (SES) computer program. The SES program simulates various
fire scenarios and calculates the critical air velocity required to prevent back layering of hot
smoke.
Platform Ventilation System
Heat is introduced into an underground station from lights, people, electrical equipment and from
the operation of trains. Mainly braking resistor grids, air conditioning condensers, friction brakes