Developing a framework to combine the different protective features of a safe system [R24]

While the overarching objective of the transportation system is to provide mobility, transportation professionals dedicate significant resources to build a safe system. The aspirational objective is to establish a system on which no road user can suffer catastrophic outcomes. To accomplish such a safe system, it is necessary to effectively harness all the core protective opportunities provided by the system. Despite the increasing consensus that this needs to be thought of as a systems problem, the considerations for each of these layers of protection are siloed, and many of the protective features are evaluated in terms of potential lives saved due to a specific improvement. To address this, the research identifies kinetic energy as the appropriate common denominator that captures the overall protective characteristics of the system. It is not practical to aggregate the additive capability of the system’s elements to control or contain kinetic energy. However, it is valuable to evaluate the cumulative kinetic energy of entire system and proposes a framework that can support researchers and practitioners in better understanding the safety mechanism and identifying strategies that may have been overlooked.