Let’s build giant tree circles in every Seattle neighborhood

A few weeks ago, my spouse Kelli and I were talking about how to bring together the desire for large old trees in our city and our need to better calm traffic and improve biking and school walk routes. Watching the story unfold this week about folks protesting to stop the removal of a western red cedar from private property brought our conversation back to the front of my mind. I understand why people care so much about trees because I am one of them, but tree advocacy too often morphs into fighting against increasing our housing supply. These things don't need to be mutually exclusive. That's where the giant tree circle comes in. Here's a rough sketch:

Ryan DiRaimo posted a somewhat similar idea over at the Urbanist recently that could be applied to nearly every residential intersection. It calls for the city to create tree planting areas in the existing no-parking zones 20 feet from each sidewalk curb cut and 30 feet from each stop sign. So long as the new planting areas are planned properly so that they do not reduce visibility at the intersection, it's a great idea for increasing planted space and stormwater retention.

The giant tree circle concept goes a step further. If we purposefully dedicated a whole intersection to supporting a single tree (or cluster if that's what the trees prefer), we could give it the space to grow as large as it wants to grow over the next generation or two (or three or four). Because it lives in dedicated public right of way, the people would own it rather than relying on private property owners to protect it. The giant tree circle concept would be for special locations where two neighborhood walking and biking routes intersect, such as two neighborhood greenways/healthy streets or routes to school or shared streets. SDOT could dead-end the streets for driving and create a special area that allows for walking and biking while also creating a mini park. Lose some of the pavement, preserve paths for walking and biking, then maybe add some benches or a small play structure or a BBQ grill or public art or whatever fits each micro neighborhood's needs and desires. Planning and creating the space could be a fantastic community-building exercise. At the center could be a glorious tree of a species that dramatically stands out from the rest. I love the idea that a person walking or biking could navigate a neighborhood using giant trees as waymarkers. Turn left at the giant tree, then my house is two more blocks on the right."

By reserving a large radius around the tree or tree cluster at the center of the intersection, SDOT's excellent street tree program could plant varieties that don't fit in typical planting strips. I am no arborist, so I do not know which varieties of tree would be best suited for this idea, but I do know that many varieties of giant trees make terrible street trees due to their pavement-destroying root systems and, well, their size. SDOT maintains a helpful database of street tree varieties that work in different situations (such as different planting strip widths or under power lines). SDOT's arborists will know which tree varieties would thrive if given a radius potentially several times larger than most street trees get.

This is not a completely new idea. Seattle already has a bunch of examples of older neighborhood traffic circles where trees have been able to grow to significant heights, though those intersections are still typically open to traffic. Perhaps the best example is at 17th and Republican, where a 1970s-era traffic diverter forces car traffic to turn while allowing walking and biking. At the center is a planting area with an impressive tree.

Looking south on 17th Ave E at E Republican Street.Looking north.

There's also this large traffic circle at 17th Ave NE/NE 63rd Street/NE Naomi Place that has paths through it and a bench in the middle:

I absolutely love these intersections, and I wish the city had copied these successes in more places because they are unfortunately rare. Fully occupying the intersections would take things a step further, creating more space for community. Removing some pavement reduces the stress on the stormwater system, and additional water retention elements could be incorporated into the design (perhaps Seattle Public Utilities could be a partner).

We also loved this playground we stumbled across in Amsterdam that was built within the street right of way:

From Street View.My kiddo loved that we found a secret playground while biking around. Photo by Kelli Refer.

Planting more trees within city-owned right of way, whether a giant tree circle or through the city's great Trees for Neighborhoods program, is also likely the fastest way to expand the tree canopy in places that have been historically underserved by the city's greenery investments, especially low-income communities and communities of color. It's not an accident that you have to look to Ravenna and a wealthier part of Capitol Hill to find the best examples of traffic circles that are so old they now have mature trees. Closing an intersection to cars also dramatically reduces traffic on the whole street, which is especially important on neighborhood greenways and healthy streets in parts of the north and south ends of the city that are missing sidewalks. Walking on-street can be safe for people of all ages and abilities if the traffic volumes are extremely low, but it only takes a little cut-through traffic to undermine safety and comfort. Traffic diverters eliminate a street's role as a cut-through option.

Tree advocates can try to resist people cutting down trees on their private property, but that's a losing battle. If someone really doesn't want to keep their tree, there's only so much anyone else can do about it. Instead, let's expand public ownership of trees and keep looking for ways to add more trees within our public rights of way. There is a lot of extra public asphalt in our town sitting in spaces that could be put to better use for generations to come.