Developing a Framework to Combine the Different Protective Features of a Safe System

To deliver a Safe System, it is necessary to effectively harness all the core protective opportunities provided by the system. This study explores what means are currently available to evaluate the cumulative ability of the system to protect street users. This research identifies kinetic energy as the appropriate “common denominator” since it captures the overall protective characteristics of the system. When observing values of kinetic energy in the transportation system it is apparent that it is not only the magnitude of the kinetic energy that matters. For example, the amount of kinetic energy carried by an airplane is very high but that does not immediately translate to a higher risk. In other words, bigger kinetic energy does not always translate to a bigger problem.

Building on kinetic energy as the focal variable, the research team developed an aggregate approach that acknowledges that kinetic energy is a crucial attribute of the system on both ends of the equation. On the one hand, the amount of kinetic energy carried by the subject mode determines the potential magnitude of the problem, and on the other hand the capability of the system to control or contain that kinetic energy determines the system’s ability to respond.