Wednesday, May 27, 2009

Pringle Creek + the Gravel Verge

Building on some recent posts on the SEA streets in Seattle, and Crown Street in Vancouver, BC, a few images of Pringle Creek - the uber sustainable community in Salem, Oregon. A significant feature is the use of the gravel verges - popularized by Patrick Condon these curbless sections allow infiltration on the edges of streets, as well as reducing construction costs.

:: Site Plan - image via Jetson Green

From their site: "Pringle Creek Community in Salem has one of the largest installations of pervious asphalt in the country. The green streets are narrower than conventional streets, using less materials to build and calming traffic. They have no curbs, which reduces construction costs and allows vegetated swales to capture, absorb and clean stormwater runoff."

:: image via GreenWorks

:: image via Pringle Creek

The use of permeable asphalt and curb bulb-outs is sort of a belt and suspenders approach, but together creates a very unique environment and aids in traffic calming and the ability to manage greater amounts of stormwater runoff (and look, sidewalks!) It will be interesting to see how the permeability holds up during construction of the houses, which is slowly happening over time... slowly.

:: images via GreenWorks

Another aspect of the community was the ability to route roadways, and limit impacts to existing large trees, giving a feel of a much more established community. And the rain gardens are waiting patiently for new residents to enjoy them.

:: images via GreenWorks

It's definitely telling to see the interface with the porous and non-porous surfaces, here at one of the site entries. Also a quick video showing the performance of the permeable asphalt pavement. (both via the Pringle Creek Blog)

:: image via Pringle Creek Blog


  1. great stuff jason! thanks for the great pictures.

  2. Good stuff. Anyone know how the pourus cement works in snowy/freezing environments?

  3. I like the idea of the gravel verge, but I'm curious about how it's intended to be sustained/maintained over time. Will it be allowed to turn gradually into well-drained soil, as fine particles accumulate and plants take root, or will it be removed and re-screened occasionally to keep it gravel?

  4. Scott: I haven't done research on snowy environments (having come from one I can see some issues). I know that permeable (or other pavers) are difficult due to snow removal, but interesting thought to see what limitations there are with asphalt and concrete. Anyone out there have thoughts on that?

  5. Toby.
    Good point - I think that there would be some additional maintenance with the gravel verge. Most of the unfinished streets that just have gravel right now have become more of a soil mix and have grass or other vegetation growing in them... I think if it maintains permeability and isn't muddy that would be ok - but it'd be good to keep tabs on some of the older projects to see how the gravel holds up long-term. Thanks for the comment.

  6. This process of porous asphalt with a gravel verge would be a costly maintenance item and perhaps unnecesary in a cold climate where concrete curbs and permeable pavements have been used with great success in the Chicago market and other areas of the US. This system can also accept fire trucks and snow plows without damage and has a proven record of reducing maintenance costs.I would suggest visiting for more information regarding your topic.

  7. I live in WI and there isn't too much issue with pervious asphalt or concrete with the freeze/thaw becasue the water gets through the pavement so quickly it doesn't have time to freeze in the pavement. As long as your storage layer gets below the frost line you should have no (or very minimal) problems. I was amazed at how the pervious concrete we installed performed during a small thaw in February its first season.


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