Content area
Full text
ABSTRACT
This paper provides both a means for tailoring the current rail transportation tunnel emergency egress guidelines to the specifics of the individual system application and a strategy for improving the overall fire-life safety of passengers and crew during a mid-trainfire event. These dual objectives are accomplished via the development of an equation based upon the time required to complete the various activities associated with a train evacuation and subsequently rearranged to solve for the required distance intervals between successive tunnel egress elements. The paper then provides examples of how this equation may be put to use for three hypothetical rail systems, as well as a correction for one of the examples as a result of a discussion on controlled evacuations. Finally, a parametric study is provided in order to evaluate the relative impact of changing certain variables within the equation.
INTRODUCTION
National Fire Protection Association (NFPA) Standard 130, Fixed Guideway Transit and Passenger Rail Systems (NFPA 2003), includes guidelines for tunnel emergency egress provisions. The 2003 edition of the standard denotes in paragraph 6.2.4.1 that "emergency exits shall be provided from tunnels to a point of safety" and in paragraph 6.2.4.2 that "within underground or enclosed tramways, the maximum distance between exits shall not exceed 2500 ft (762 m)" (NFPA 2003). The latter of these two statements is explained further in paragraph A.6.2.4.2 of the standard, which draws a parallel to NFPA Standard 101 (NFPA 2006) and its consideration of an affected, or unavailable, exit in specifying 2500 ft (762 m) as the maximum permissible travel distance between tunnel exits. However, in paragraph 6.2.4.3.1, the 2003 edition of Standard 130 also states that "cross passageways shall be permitted to be used in lieu of emergency exit stairways to the surface where trainways in tunnels are divided by a minimum of 2 hour-rated fire walls or where trainways are in twin bores" (NFPA 2003). Paragraph 6.2.4.3.2 of the standard goes on to provide seven conditions under which cross passageways may be utilized in lieu of emergency exit stairways; these conditions are noted below.
1. Cross passageways shall not be farther than 800 ft (244 m) apart.
2. Openings in open passageways shall be protected with fire door assemblies having a fire protection rating of...