Fixed Fire Fighting and Emergency Ventilation Systems for Highway Tunnels

The Federal Highway Administration conducted research (from 2018 to 2024) into the use of fixed fire fighting systems (FFFS) in highway tunnels. The main objective was to consider the operational integration of highway tunnel emergency ventilation systems (EVS) with installed FFFS. The research was conducted in stages including the following: literature survey, industry workshop, computer modeling, laboratory-scale testing, and final research summary report. With regard to the objective of FFFS and EVS operational integration, an outcome of this project was a demonstration of the ability of the FFFS to improve ventilation performance (under longitudinal ventilation) through cooling of the combustion products. This demonstration was provided by considering previously conducted full-scale testing, the laboratory-scale testing conducted as part of this project, and computer modeling. Design considerations for a one-dimensional analysis for sizing a longitudinal ventilation system with FFFS included were made and suggested practices for FFFS and EVS integration are provided. This paper summarizes the above findings as well as other findings including a compilation of FFFS test results for fire heat release rate (based on previously conducted research) and the outcomes of computational fluid dynamics (CFD) models using Fire Dynamics Simulator (an open source CFD software developed by the National Institute of Standards and Technology).