What is HSI? And why does it matter to the rail industry? 

The rail industry is evolving rapidly. Among the changes facing the industry is the introduction of new technology in the locomotive cab, such as Positive Train Control (PTC), intended to increase safety and minimize accidents. When new technologies are introduced, it is important that it is done in a way that enhances, rather than hinders, operator performance. Effective Human-Systems Integration (HSI) ensures that this happens, and that new technologies are optimally designed for safe, efficient, and reliable use. 

Human Systems Integration is a "systematic, organization-wide approach to implementing new technologies and modernizing existing systems."  It combines "...managerial philosophy, methods, techniques, and tools designed to emphasize, during the acquisition process, the central role and importance of end-users in organizational processes or technologies" (Reinach and Jones (2007:3).

Human Systems Integration refers to efforts to increase safety, manage risk, and optimize performance of those who work in socio-technical systems. HSI considers the human role (both individuals and teams) as part of a system that includes tasks, technologies, and environments. HSI ensures that characteristics of people are considered, and accounted for, throughout the design and development of systems. The HSI approach can increase operator acceptance and usability of technology, and enhance the likelihood of successful deployment (Roth, et  al 2013).

What is a "spiral development process?"

Use of a "spiral" development process, as the diagram at right shows,  minimizes costly redesigns, by applying knowledge about human abilities and limitations during each step of design and development. Startng at the center, developers learn about work (such as rail operations), develop requirements for what is needed, and verify them. They then develop rough to more refined solutions, verify them, then eventually complete a validated solution that is ready to implement. 

This kind of HSI process  makes sure at each step that the solution being developed does what it is required to do to improve operator performance.