Residential Density
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Residential density refers to the number of people or households within a geographic area. Often local and regional governments zone for densities that will support transit service, as low-density development is difficult to serve by transit. There are not clear thresholds for transit-supportive density, as it depends in part on the type of transit service. However, the threshold is generally considered to be over 8 dwelling units an acre. Higher densities will support greater levels of transit frequency.
Higher residential densities are one component of compact neighborhoods (aka New Urbanist, smart growth, or traditional neighborhoods) that typically offer better Local Accessibility. This relates to the concept of the 15-minute city or the 20-minute neighborhood, where daily needs are within a short walk or bike ride from home. |
Proven Outcomes
Reduced VMT
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Reduced GHG
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Increased Walking
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Increased Physical Activity
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Increasing residential density decreases vehicle miles traveled (Stevens, 2017, paywall) and greenhouse gas emissions. Compact neighborhoods (aka New Urbanist, smart growth, or traditional neighborhoods) are recommended to increase physical activity (Community Guide, 2016).
It is difficult to disentangle the effects of density relative to other measures of the built environment, such as street network connectivity and land use mix. While density is among the most influential of the so-called 5Ds (density, diversity, destinations, design, distance), it may not be the most important variable (Salon et al., 2012, paywall). Increases in density should be considered along with other strategies, such as mix of land uses and walking and bicycling infrastructure, to achieve community goals (Boarnet & Handy, 2014). Other "D"s that have been studied for their role in influencing travel behavior include demographics and demand management.
It is difficult to disentangle the effects of density relative to other measures of the built environment, such as street network connectivity and land use mix. While density is among the most influential of the so-called 5Ds (density, diversity, destinations, design, distance), it may not be the most important variable (Salon et al., 2012, paywall). Increases in density should be considered along with other strategies, such as mix of land uses and walking and bicycling infrastructure, to achieve community goals (Boarnet & Handy, 2014). Other "D"s that have been studied for their role in influencing travel behavior include demographics and demand management.
Likely Outcomes
Reduced Vehicle Use
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Reduced Air Pollution
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Increased Community Vibrancy
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Possible co-benefits include reduced vehicle use and air pollution (Community Guide, 2016) and improved community vibrancy through increased in active travel (Boarnet & Handy, 2014).
Equity and Inclusion
Strategies that involve changes to the physical environment may increase the attractiveness of an area. An increased demand for housing may result in increased property values or rents and could lead to involuntary displacement if appropriate mitigation strategies are not put into place. The lessons learned from anti-displacement efforts in several cities can be found in this PolicyLink report. Practitioners can evaluate the risk of displacement through the methods described by Chapple et al. (2017) or Bates (2013).
Complementary Strategies
Implementation Guidance
Guides & Reports