Does block size matter? Smaller isn’t necessarily better for pedestrians

A. Sevtsuk & R. Kalvo & O. Ekmekci    "Pedestrian accessibility in grid layouts: the role of block, plot and street dimensions," Urban Morphology 20 (2016): 2

The take-away: This quantitative study concerns how block and street dimensions relate to pedestrian accessibility. Contrary to previous studies of urban form and walkability, these findings suggest that smaller blocks are not necessarily better for pedestrians. The study concludes by illustrating which block sizes maximize pedestrian accessibility.    

Abstract: Research on urban form and walkability suggests that on average smaller blocks are better  for pedestrians. We explore how block sizes, plot dimensions and street widths affect  pedestrian accessibility in regular grids. Pedestrian accessibility is captured by the gravity  index, which is proportional to the number of neighbouring plots that can be reached  within a given walking radius and inversely proportional to the travel costs involved.  Pedestrian accessibility is measured for the original town plans of well-known US and  Australian grids and compared with thousands of computer simulated grids, analysing how  close the grids come to the theoretical maxima of pedestrian accessibility, given plot sizes  and street dimensions. The findings show how dimensions of plot frontages and depths,  street widths and block lengths affect pedestrian accessibility in gridiron urban  environments. Block lengths have a non-linear relationship to accessibility and smaller  blocks are not necessarily better for pedestrians. In many cases, larger blocks have greater  pedestrian accessibility than smaller blocks, which might explain previous variable findings  on the effects of blocks sizes on walkability. Though block lengths in most of the famous  grids we investigate come close to achieving maximum possible pedestrian accessibility  levels, some of them could provide users with as much as 12 per cent more accessibility if  their lengths were optimized for pedestrians. The lengths of the Manhattan and  Indianapolis blocks come closest to maximizing pedestrian access, given their original plot  and street dimensions. We illustrate a few prototypical block sizes that maximize  pedestrian accessibility and may be suitable for pedestrian-friendly subdivisions in  contemporary urban planning.

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