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Forward Motion: Transportation Planning

Making the Connection

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Legend has it that a group of nineteenth century American tycoons were developing a town way out on the edge of the Wild West and decided to try something new. They'd found that corner buildings were worth more than those located mid-block, so it stood to reason that a town with more corners would do well. The result? A downtown with a tight street grid and intersections as little as 200 feet apart.

... I know what you're thinking: "Yeah, that's nice, but we're not Portland." Do shorter blocks and more intersections -- that is, greater street connectivity -- provide any benefits for communities that don't have a dense urban core?

In a recent report "Planning for Street Connectivity: Getting From Here to There," transportation planning experts Susan Handy, Robert G. Paterson, and Kent Butler analyzed thirteen communities (including four with populations in the 6,000 to 32,000 range) that have connectivity ordinances.

Most of the cities and towns in the study have set block length limits for local streets, generally falling in the range of 500 to 600 feet. Some have also placed maximum distance limits on spacing between intersections along arterial streets. Requirements vary according to the roadway context: higher-speed, wide streets such as commercial arterials need more space between intersections and driveways in order for traffic to flow properly, while more frequent cross streets in residential areas can help to slow traffic down.

Regardless of their size, communities can realize three major benefits from better connectivity: shorter trips; a wider variety of travel choices; and more cost-effective public services and infrastructure.

Creating more direct connections shortens travel time, which effectively brings people closer to their destinations. With more available connections, community residents can get to schools, shopping centers, and other spots that may have simply been off their radar before -- not because these places were too far away, but because they were too far out of the way.

Meanwhile, firefighters, police, and ambulance services can save precious minutes reaching the scene of an emergency, and can serve a broader area without driving up their operating costs. Similarly, greater connectivity can reduce costs of providing other services, such as waste collection, by decreasing travel time and mileage. ... But what about that popular suburban street type: the cul-de-sac? ... All the communities in the connectivity study do allow cul-de-sacs, but restrict their lengths, from as little as 200 feet to as much as 1,000. Several also direct developers to create multiple entrances to their site, provide cross-access between commercial properties, and/or include stubs to indicate future connections.

That being said, it's really not necessary to force open every subdivision in order to improve community-wide connectivity. It would be counter-productive (not to say, poor planning) 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. ...

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photo of Hannah TwaddellHannah Twaddell is President and founder of Twaddell Associates, LLC, a consulting practice specializing in community planning, public engagement, facilitation, and education. Based in Charlottesville, Virginia, the firm provides planning, facilitation, and educational services to communities, government agencies, and private organizations across the U.S.

Before setting up Twaddell Associates, Hannah was a Senior Transportation Planner with Renaissance Planning Group, where she has worked on transportation planning and public involvement projects in several states. Prior to that, she served as Assistant Director of the Thomas Jefferson Planning District Commission (in Charlottesville) and as chief staff to the Charlottesville-Albemarle Metropolitan Planning Organization.

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