Shearing Layers of Space: Exploration of Permanency and Temporality in the Public Realm

Stewart Brand famously provided a framework for considering change within buildings through his idea of “shearing layers,” itself based on earlier ideas from Francis Duffy and Alex Henney. In each case, a loose hierarchy starting with the relative permanency of the site, the building structure/shell, and to a lesser extent the skin, to the more temporary building services, space plan, and ultimately the scenery/stuff that fills the buildings. This article transposes this method of analysis from buildings and structures to public urban space. It achieves this by adding a time dimension in the form of a “rate of change” or renewal to the different layers of site, surface, services, space (spatial configuration), surroundings/skin, signage, and stuff within the public space. While it was initially intended as a thought experiment relating to society, the idea of long-term thinking is a beneficial tool for urban designers and planners. Demonstrated using a city centre public space case study, we present the object-orientated approach to recording and mapping the “rates of change” ranging from constant, hourly, daily, monthly, and yearly through to renewal over decades and centuries. The output is presented dynamically, as a chronological map progression supported by mixed archival secondary sources and primary data gathered using remote sensing and other photographic evidence. A move from end-state planning within the public realm, to thinking about the variable nature of change will support a more flexible and resilient public realm. As we increasingly need to be responsive to challenges, and opportunities, having a better understanding of the time cycle and adaptability of the different layers of our public realm will only benefit the city.