Urban planning dilemmas

Donald Appleyard was a British born, American urban planner, noted for his book Livable Streets, published in 1981 by the University of California. Full of interesting insights and empirical observation. I especially liked this representation of the connection between traffic volumes and community interaction.

Light traffic is 2,000 vehicles a day, moderate traffic is 8,000, and heavy traffic is 16,000 vehicles a day.

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Low traffic is associated with high community engagement and inclusiveness.

High traffic is associated with community dissolution and fragmentation.

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I would add that there are actually three independent variables which drive crime and community erosion. Traffic volume is certainly one but there are others.

Traffic Volume – Vehicles per day or per hour

Traffic Nature – Intercommunity volumes (connecting between communities) or Intracommunity volumes (connecting within the community)

Traffic Heterogeneity – Resident and non-resident

The higher the traffic volume the lower the community cohesion.

The greater the percentage of traffic which is between communities (rather than within community), the lower the community cohesion.

The greater percentage of population within the community area who are non-residents, the lower the community cohesion.

The corollary, from the perspective of urban planners, developers, and politicians, is that you can increase urban density but if you increase traffic and traffic churn with defined spaces, you are going to make it difficult to foster a healthy community environment.