Livability - a definition
Sustainability - The Brundtland Commission of the United Nations on March 20, 1987 wrote what is perhaps the most famous definition of sustainability: "sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs." While we can critique this definition in many ways, from this post's perspective, the most salient point about it is its temporality. It is about future vs. present. We need a similar definition for here vs. there.
Livable Streets by Donald Appleyard
I have been working with Bruce Appleyard on some issues around Street Justice and Livable Streets. He has written extensively on the issue, see e.g. Appleyard et al. on Livability Ethics. This got me interested in Livability definitions. I think the most useful would be something that spatially mirrored the definition of sustainability.
Livability, a definition (by me): (Livable development): “meets the needs of members of the local community, without compromising the ability of non-members to meet their own needs"
To be clear, there is a natural tension between here and there, just as there is a tension between now and then. The job is to balance these, to differentiate between needs and wants. Within transport it is in many questions a case of through traffic vs. local movement. But how much of that traffic is necessary, as opposed to optional. Some traffic must traverse the neighborhood, and without a proper hierarchy of roads, uses streets designed in a different era for different purposes with different numbers of cars in mind. Every car moving on the street moving east-west is a barrier to someone attempting to walk north-south. The faster the cars, the fewer gaps in the barrier, the longer the delay for the pedestrian.
However in contrast with sustainability, where the balance needs to re-focus on the needs of the future relative to the present, discussion about livability in transport implicitly aims to focus on the needs of the members of the local community at expense of the wider region. In contrast with transport, housing discussions concern the needs for a local area to accept more housing for the sake of the region, these are the debates about NIMBYism and zoning.
When travelers do not pay their full cost, the overconsume ... they travel too much. This causes them to travel too far, traversing too many streets through too many neighborhoods, making neighborhoods less livable. They also thus consume too many resources (energy, clear air, safety) making them unavailable for future generations, making human life on earth less sustainable.
One solution is obvious, if politically difficult: charge travelers their full cost to society, the cost of the congestion they impose, the cost of pollution, the cost of energy, the cost of hazard, and even, if it can be quantified, the cost of disrupting social networks in local neighborhoods, which may be in part capitalized in the cost of real estate. We discuss this more in A Political Economy of Access.