Visualizing Density

The book aims to link perceived density to measured density by providing a catalogue of 250 neighbourhoods from the US, each example illustrated with four aerial images, a street pattern diagram and a dwelling density measure in units per acre. This is not an uncommon attempt to provide a tool helping the understanding of the relationship between urban density measures and built form outcomes, several such catalogues having been published in the last decades internationally.The strength of this particular density catalogue is the extensive high quality aerial imagery. However, there are many limitations to its usefulness. Firstly, we normally perceive neighbourhoods from ground level, not from the air, but no eye level imagery is provided. The second key problem is that scale, a key aspect of any density measure, is not consistently used. While the book refers to neighbourhoods, the provided density measure of units per acres has been often calculated for a single block only, and is not clear whether is net or gross. For homogeneous suburban neighbourhoods this is not a major problem, but for the diverse inner urban areas the density of a single block can widely differ from that of the neighbourhood. Thirdly, it would have been fair to warn the reader of the multiple limitations of the used density measure of units per acre, such as that the presence or absence of non-residential uses is ignored, that the actual size of a unit is ignored, or that family size can largely vary from one neighbourhood to another, and thus the density of people might compare differently than the density of units. Finally, the street pattern diagrams provide only limited information, as street widths -a key aspect of neighbourhood density- are not accurately represented, a scale bar is not provided, and there are inconsistencies between the scales (such as between New York and Seattle). In the end is not surprising that all key books and research papers about density are missing from the list of references.Overall the book is an interesting attempt to help a better understanding of density, with many impressive images, but falls well short of seriously documenting the chosen neighbourhoods, and risks confusing the reader.

The most interesting part of this book is the pictures that comprise the second half of the book. For dozens of different density levels (ranging from less than one dwelling unit per acre to over 200 units per acre) the book shows photographs of several examples. Usually, the book shows both attractive and less attractive examples of a given density.These pictures reveal a variety of surprises. For example, when one thinks of houses looking as if they are packed together, one might think of high density- but where big houses are next to each other instead of being separated by trees or grass, they can appear unpleasantly crammed even at one or two units per acre. On the other hand, a tree canopy can make a neighborhood with a dozen houses per acre look fairly spacious.Another surprise is that high density doesn't necessarily have to mean apartments or high rises- there are small-house and row-house neighborhoods with 20-50 dwelling units per acre, while some high-rise areas are not tremendously dense (due to the presence of plazas and parking lots where buildings could be).Though much of the text reiterates well-worn arguments for more compact development, some of it addresses a genuinely interesting question: why do neighborhoods of identical densities vary in attractiveness? The book suggests that less attractive neighborhoods tend to (1) have fewer shade trees, (2) have less variety in housing types, and/or (3) are less walkable (because streets are not interconnected enough for people to walk to neighbors' houses, or because commercial areas are not within walking distance).

I like the book. It does have a scattering of examples and could have more numerous examples, but this would be a different book. As is, it provides a concise look at American building form unbiased toward a specific style (Such as books that only showcase new urbanist designs). In addition, it is an easy read.

This book is far more useful than many textbooks. It very clearly describes its eponymous objective. HIGHLY recommended for anyone interested in alternatives to the sprawling status quo.

Difficult to find good visual information on density - very useful in that regard but pretty much stand alone.