Transportation safety is an issue of interest to both the transportation industry and the public at large. Over its history, the U.S. government has issued numerous transportation safety related regulations and laws to both protect transportation workers, as well as the motoring public. While transportation safety today is at its highest levels, there is always room for improvement. Beyond safety for societal protection, transportation carriers understand the benefit to the bottom line of improved safety. Much of the impetus for improved safety programs comes from within, in the form of increased profitability through loss mitigation, rather than from external government directives. Over the past 20 years a shift has begun regarding the nature of workplace safety programs in general (Johnston and Hayes, 2005) and transportation safety programs in particular (Melton and Van Dyke, 2004; Olson and Austin, 2001; Ludwig and Geller, 2000). The shift has been away from being primarily regulation and rules-based programs, toward more judgment and Behavior-Based Safety (BBS) programs. The BBS approach encompasses many different themes and principles (Geller, 2001, 2005; Johnson, 2003; Wirth and Sigurdsson, 2008 among others), organized around the importance of the role of the individual human decision maker as being key to improving safety performance. A key difference between the traditional programs and the newer BBS programs is the balance between the role of "rules" vs. the role of human "judgment" in safety processes. It is this issue that is the focus of the current research effort.
Rules based programs are typically compliance oriented, rewarding safety targets achieved (Atkinson, 2000) and focusing on monitoring and controlling the activities that are deemed critical to ensuring safe operations. Judgment based programs are behaviorally oriented, focusing on training and education of employees to aid them in making safety sensitive decisions, and rewarding safe behaviors themselves rather than safety target achievement (Atkinson 2000). An implied tradeoff exists between the psychosocial or human factors (behavioral) elements, and the rules that provide a substitute for those elements. While any successful program generally includes both rule-based and judgment-based components, the relative emphasis changes over time and context. This research examines this change in transportation safety programs from a single case perspective and assesses whether there is evidence that judgment-based programs lead to safer performance than rules-based programs. While no integrated safety program will consist of purely rules or judgment alone, the balance or relative emphasis between the two components is investigated here. The perspective taken in this research report is that the term "judgment based safety programs" refer to that subset of the Behavior Based Safety philosophy that emphasizes the role of judgment in the decision making process (in contrast to a focus on rules as a substitute for judgment).
The transportation industry has a long history of striving to establish the safe movement of people and cargo. The primary way the transportation industry has sought to reduce transportation mishaps is by the employment of various transportation safety programs. In general, these programs can be classified as belonging to one of two program types; rules-based programs, and behavioral or judgment-based programs. Transportation safety analysts have recognized several factors correlated with accidents. From a basic framework of carrier behavior (carrier actions and culture), societal norms (embodied in safety regulations), and situational factors (largely uncontrollable factors present in the physical environment), Mejza et al. (2003) note that "... most studies focus on the direct relationship between carrier behavior and transportation safety or on the indirect relationship between societal norms and transportation safety. …