NCHRP Report 836 presents guidelines for emergency ventilation smoke control in roadway tunnels to facilitate human evacuation and emergency responder safety. These guidelines consider tunnel geometrics such as tunnel altitude; physical dimensions (i.e., length, cross-section); type of traffic flow (i.e., single or bi-directional flow); and fan utilization and placement. They also consider cargo types and quantities as they pertain to fire heat release rates (FHRRs) and ventilation requirements. The guidelines determine the effects of ventilation on tunnel fires including fire size, and the interaction of firefighting and ventilation system operation. The material in this report will be of immediate interest to tunnel owners and operators, law enforcement agencies, first responders, designers, and ventilation equipment vendors.
In normal operation, ventilation ensures sufficient air quality in the tunnel, generally by diluting pollutants. During the self-evacuation phase (also called the self-rescue phase), the ventilation system aims to create and maintain a tenable environment for the evacuation of tunnel users. Specifically, this environment consists of acceptable visibility, heat, air temperature, thermal radiation, and air quality levels. During the firefighting phase, the ventilation system control and operation should be part of the standard operating procedure for the tunnel so that firefighting and rescue can be carried out in accordance with the emergency response plan. Currently, the design and operation of emergency smoke control varies from project to project in the absence of consistent and standardized practices. There was a need to identify the best operational practices for emergency ventilation smoke control in roadway tunnels. Research performed under NCHRP Project 20-07/ Task 363 by Jacobs Civil Consultants Inc., developed guidelines for emergency ventilation smoke control in roadway tunnels to improve human evacuation and emergency responder safety.