The Project for Public Spaces has written an article on "Streets as Places." It looks at the role street design plays in aiding or thwarting a sense of community. Also, the best-planned streets function within their communities as a "town square," and the article outlines three guidelines for ensuring this. 

• Design for appropriate speed. Road speed must respect streets as places for people and not just conduits for cars. In cities and town centers, commerce needs foot traffic that suffers with higher speeds. Thus, access, not automobile mobility, should be the priority in city centers.
• Plan for community outcomes. Communities should envision what kinds of places and interactions they want to support and plan a transportation system that is consistent with this vision. Roadway projects that are planned around broader community outcomes can help increase developable land and create open space, while reconnecting communities to their neighbors, a waterfront, or a park. Overall, communities should envision projects with broad public benefits in mind.
• Think of streets as public spaces. Roadways, parking lots, and transit terminals should serve more than just automobiles and more than the singular purpose of movement.  The article provides numerous recommendations and strategies for activating and reclaiming sidewalks, roadways, parking lots, and even major urban arterials in ways that reclaims them as places, as healthy and beneficial "town squares."

The paper goes on to provide a list of 10 qualities that, in conjunction with the three above principles, helps streets contribute to the success of healthy, vibrant communities.