Shear forces: a conceptual model for understanding (and coping with) risk, change, and technical debt

A student searches in vain for a seat close enough to a power outlet to plug in her laptop. The IT department maintains a Windows XP server to support critical software for which there’s no modern replacement. Your local fitness studio has a never-used, wall-mounted iPod dock set into the drywall.

Our work processes naturally evolve, improve, and adapt to changing environments. Because of this, we often find ourselves in situations where the supporting components of the system struggle to keep up. This is because the various layers of a system evolve at different speeds: software can be purchased and deployed relatively quickly, but hardware is only refreshed every three years; furniture is easy to rearrange, but updating building infrastructure is costly and disruptive; complex workflows are built on legacy components that linger long after their normal service life. To borrow a concept from fluid dynamics, the result is a “shear force” where layers at different velocities interact. Too much shear leads to turbulence, which can actively disrupt the useful work of the system.

Shear forces can’t be completely avoided, and indeed attempts to proactively manage them sometimes lead to significant sunk costs. But considering change, risk, and technical debt in terms of shear can help us to make decisions in a more flexible and future-resistant way. In this presentation we’ll look at examples of shear forces in both physical spaces and library systems, to better understand how we can observe, predict, and account for shear in our work. We’ll explore how shear as a conceptual model can help us plan for changes not yet upon us, and consider how to make the liminal aspects of our systems, where the layers come into contact, more tolerant of shear forces, in order to ensure that the system remains performant even in times of change.


04:00 PM
20 minutes