Other human senses factor into this characterization, such as the distances at which we can perceive another human form, then specific person, then body language, then facial expression; or at which we can conduct a conversation and the varying distances for different situations (a helpful scale from intimate distance, personal, social, and public).
Good city design, then, in architecture, streets, blocks are scaled to this speed, range of sensory indications, and comfort. Cities built prior to automobiles are, by and large, designed on just this scale; the size, speed, and ‘senses’ of vehicles, paired with the monumentalizing, isolated architecture of Modernism effectively destroyed this fine-grained urban complexity. This transition in urban development is neatly summarized by Gehl by comparing 5 km/h (3 mph) architecture and 60 km/h (36 mph) architecture:
“Five km/h architecture is based on a cornucopia of sensory impressions, spaces are small, buildings are close together, and the combination of detail, faces and activities contributes to the rich and intense sensory experience…
Driving in a car at 50, 80, or 100 km/h (31, 50, or 60 mph), we miss out on the opportunity to grasp detail and see people. At such high speeds spaces need to be large and readily manageable, and all signals have to be simplified and magnified… only generalities are perceived…
Taking a walk in a 60 km/h architecture is an impoverished sensory experience: uninteresting and tiring” (44).
Gehl illustrates the difference in architecture with handsome multiple facades and blank ground floor facades, and two benches, one with curving armrests and backs, the other one of those RENT A BENCHES, its form reduced to symbol.