December 13, 2010

Uptown Normal's blue-green roundabout

The term "blue-green" is taken from the Blue-Green Building website maintained by Friends of Five Creeks in Berkeley, California.  We have used the term to describe a traffic circle in Uptown Normal, Illinois because the circle collects and filters stormwater (blue) and features a park and uses plants to filter runoff (green).  All plan images were created by Hoerr Schaudt courtesy of Hoerr Schaudt Landscape Architects with the exception of the Uptown Circle rendering and the Potsdam Gate plan image.


Uptown Normal's blue-green roundabout was designed by Hoerr Schaudt of Hoerr Schaudt Landscape Architects. The traffic circle is a sustainability feature of the Uptown Plan, a redevelopment plan initiated by the Town Council of Normal in 1999.  The circle "connects Beaufort Street, North Street, Constitution Boulevard" and "replaced a formerly awkward intersection at that location."


A roundabout design was selected for three reasons. One, Federal Highway Administration research showed that traffic circles reduce fatalities, injury accidents, and pedestrian and vehicular conflicts. Two, traffic flow is more efficient through a circular system. And three, less idle time means less air pollution.


There are several innovative elements of the Uptown Normal Circle.  Designer Hoerr Schaudt reused an abandoned storm sewer, converting this infrastructure into a "detention cistern" with a 76,000-gallon holding capacity.  The collected stormwater is treated with ultraviolet light and filtered in the "bog" on either side of the circle.  Cleaned and filtered water is used in the fountain.  Collected stormwater is also used to irrigate the neighborhood's streetscape.


Image: Uptown Circle rendering by Scott Shigley courtesy of Hoerr Schaudt Landscape Architects

A second innovative feature of the Circle is the incorporation of a park. Hoerr Schaudt refers to this central space as the "town green,"
a dynamic space as cars and water move around its users. The natural sounds of the flowing water help to mitigate the sounds of ongoing traffic. This intimate “round” park symbolizes the town of Normal’s commitment to environmental awareness. In addition, it serves as a gateway and icon while providing a place for visitors and commuters to wait for the train, have lunch, go to a market or see a performance.

Third, the Uptown Circle is the "first U.S. project to design an underground structural cell system for a streetscape." The structural cell system might be Deep Root's Silva Cell which is "a frame and a deck" system that provides large volumes for soil and thus root growth as well as for runoff treatment, space for utilities, and load bearing capacity for sidewalks.

Image: Potsdam Gate 1866 by Carl Friedrich Schinkel (source)
Finally, I asked the landscape architecture firm about the design inspiration and received this answer via email (thank you Peter Schaudt and Alison Strickler).
Herbert Dreiseitl’s design for Potsdamer Platz in Berlin was a big inspiration for this project.  Dreiseitl’s use of water in his work often has both symbolic and ecological meaning.  Potsdamer Platz uses rainwater collected in underground tanks to feed a complex water system that is enjoyed by the public.  He has a wonderful book called Waterscapes, Planning, Building and Designing with Water.  Some excerpts on Potsdamer Platz from the book are here: http://web.mit.edu/fmr/www/11.308/project_cases_platz.html.

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