Daniel Nairn at Discovering Urbanism brings up a great point about cul-de-sacs. Are they public goods, or truly unnecessary “socialism in its most extreme form”?
Take the standard cul-de-sac that serves a handful of households. The purpose of this design is to exclude the general public from passing through while serving the automotive needs of a small number of individuals. Does it pass our intuitive sense of fairness to declare that the entire public, say the local municipal citizenry, ought to foot the bill for what could essentially be considered a shared driveway? Perhaps a more important question: How does the government’s decision of where to draw the line between public and private encourage or discourage the connectivity of the road system?
Dan discusses that Virginia’s DOT is looking at shifting funding away from roads that don’t play a significant role in the transportation network, by using a very well defined metric:
The link-node ratio is calculated by dividing the number of links (street segments and stub streets) by the number of nodes (intersections or cul-de-sacs). A perfect grid of streets will have a link-node ratio around 2.5 and a network of complete cul-de-sac or dead end streets with only one way in and one way out will have a link-node ratio of 1.0. It is suggested that a ratio of 1.4 will provide adequate connectivity in many situations.
Unfortunately, owners of homes on cul-de-sacs have grown acustomed using their publicly-funded, communal driveways, and would suffer from decreased funding for roads they are entirely dependent upon. A viable solution would be for the municipality to grant the cul-de-sac roadway and land to the owners of the homes. The home owners could then use the street land per its highest-and-best use, and maintain their private communal driveway at their own expense. Observing the rise or drop in the value of those homes, we’ll then see if cul-de-sacs add value to the community, or are just sinkholes for public funds that benefit only a few home owners.