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-train fire 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.