What are connectivity measures?
Connectivity relates to the density of intersections and how direct paths are between places. Increased connectivity reduces the amount of circuitous travel required and often encourages shorter vehicle trips and the use of alternative modes such as biking and walking.
A simplistic measure of connectivity is the connectivity ratio which is calculated by:
A local circulation map is a method to visually examine connectivity. Streets providing local circulation were identified and mapped. The map highlights roads that provide key connections within neighborhoods and commercial centers. This information can then be used to identify areas with lower levels of connectivity. Field visits are conducted to confirm or refine the local circulation map.
Travel model post-processors that work in conjunction with spreadsheet equations and GIS software are used by many planning agencies and consultants to study local connections among employment, shopping, education and other daily travel needs. Some of the more sophisticated tools such as PLACE3S can compare access, connectivity, and multimodal travel benefits of alternative development configurations for a subarea or individual parcel, and then display results with a variety of mapping and graphic tools. Spreadsheet tools have been developed to provide the same analytic rigor without the visualization capabilities.
Who implements connectivity measures?
Connectivity requirements can help a locality or region implement its goals for growth management and transportation system performance. They can be included in the MPO long-range planning process and in small urban area plans or access management plans developed by city and/or county governments. Growing suburban areas can use measures of connectivity to help ensure new development includes sufficient infrastructure.
What are the keys to success and potential pitfalls?
Community-based Standards: Communities may differ in their desired levels of connectivity. It would be counter-productive to insist on a rigid connectivity principle applicable to every block. The key is to create strategically located links that benefit broad cross-sections of the community. As respected transportation planner Walter Kulash notes, "The real purpose of connectivity is to provide a variety of routes for daily travel, such as to schools, grocery stores, and after school activities. Kulash further observes: "Proposed street connections that face strong opposition are often a scapegoat for the things people don't like about their community. If you're connecting a quiet old neighborhood to an ugly strip shopping center, people aren't going to like it. Focus on the overall question of what you want for your community." Involving the community in establishing connectivity standards will be important in obtaining acceptance.
Where has this strategy been applied?
Examples in Montana
Examples outside of Montana
How can I get started?
A first step toward measuring connectivity is to develop an inventory of the local street network. Using GIS, a community can map the links and nodes (intersections) in order to calculate the existing connectivity ratio. To establish a connectivity ordinance, it is helpful to start by researching the small but growing number of successful ordinances around the country.
Where can I get more information?