A Sidewalk – Or A Tree Walk? (WSDOT / Dayton Ave)

If you practice environmental planning long enough – you realize many redevelopment plans don’t highly prioritize existing trees.

The ‘remove and replace’ mitigation strategy can be an easy (too easy) crutch for a site focused on total transformation. 

However, every once in a blue moon, I run across a new project where the existing environmental opportunities align so perfectly with the development needs – I’m wondering if it is some strange professional mirage put out there to make me question the amount of coffee I drank that morning. 

That’s what I think of the ‘soon-to-be’ sidewalk project brewing on Dayton Ave. In a city that is in dire need of sidewalks (there is only ~22 miles of sidewalks for 191 miles of Shoreline WA roadways), the 46.5 million dollar remodel of the Washington State Department of Transportation (WSDOT) building to accommodate approximately 200 relocated Department of Ecology employees is one of those rare ‘blue moon’ opportunities.

Dayton Ave is Shoreline’s chance to add a public sidewalk – where massive landmark trees already stand – as a gateway of appreciation for our state’s hardest working environmental stewards.

Site Tour

Having biked, bused, and (attempted) to double-stroller 60 pounds of toddler through this muddy patch of urbanity, I know exactly what the thoroughfare between N.160th Dayton Ave. and N. 155th St needs.

It needs a sidewalk.

Just to prove my point, lets take a little wet weather walk on what awaits you as you head towards the bus stop on Dayton Ave N & N 160th St.

First up: an urban minefield. Coming up towards the bus stop you immediately enter a very scary debris field of gravel, buried trail boards, hidden water meters, and a few random tree roots. Looking at this, I’m pretty sure I won’t be leaving here without a nail in my stroller tire. Possibly get something spilled down my work shirt as I try to muscle Kid #1 and Kid #2 from tipping over on this jumbled path.

Next up, looking past the bus stop, things are a bit more stroller friendly – but not by much. The asphalt is clearly buckling due to some root contact. This uneven surface still could lead to difficult times for your double stroller – and I’m sure the same could be said for a wheelchair. 

Checking out the south bound side. Maybe the grass is greener? Except, what exactly is the plan here? Do we just roll off the bus and follow the sand bags into…. the bike lane?

Back on the north-bound side, crossing the WSDOT drive, we head on over to the other side. As we make the crossing, we meet our curbside greeter: Tree #146 (Douglas-Fir, 22.5″ DBH, ~30′ canopy width) who has found himself stuck between a curb and a hard place.

This broken patch of asphalt continues for a few feet – before it abruptly ends. There is a 7-foot bench though, just at the end point. Conveniently placed really, if you want to take a quick seat and place your feet in that puddle. 

Behind, and to the left of the bench, is a walking path entrance to WSDOT. Even though it is bordered by mature trees, the space still feels vacant. To be honest, something about it reminds me of unused areas in golf courses. Those ignored places where random golf balls go uncollected and golf carts pile up overnight.

It feels vacant and useless – and a bit forgotten.

It also feels like it could be something so much more.

Moving past the bench entrance, there is still some gravel and tree litter, but the ground is uncompact and the moisture level is very low. True, it isn’t a flat concrete sidewalk – but it also isn’t that unpleasant of a ramble – even in this wet weather – with a stroller. Also, imagine the shade potential in the summer.

Looking further south, there is a bit of a drop-off behind the hydrant, but still a pretty good amount of distance between the trees and road. Plenty of space really.

Several blocks south from the WSDOT site, is another major Dayton bus stop. This bus stop space configuration can only be called “puddle island”. Three things worth noting here:

1. the tree canopy is noticeably lower and less dense,
2. the path gravel is far more compacted, and
3. the runoff levels are much higher. 

As a wet-weather biker I often call this stretch of Dayton “the River”. Because it is.

As you can see, in its current condition, Dayton only really works for cars. However, if a continuous sidewalk existed on Dayton, I have a feeling that would be a major game changer. Instead of the majority of traffic rushing through here at a 30+ mph, this “drivers only” road could easily be changed into a scenic passage for thousands of bike and bus commuters

It is often said that the ideal traveling experience is more then a route between point A and point B. It is a journey that enables major mental transitions. I can attest that when commuting home to start my ‘family nightshift’, that bit of green scenery on Dayton does a lot to help me make the mental jump from worker bee to mom.

A jaunt – and even an occasional stop – beneath the trees is ultimately what always helps me to ‘find me’.

That’s why a sidewalk which increases pedestrian site access – without removing the trees – was our goal when drafting the below proposal. 

The ‘Tree Walk’ Proposal

At the time writing (November 2020), the WSDOT site currently plans to remove 64 trees along Dayton Ave. In their place, the proposal is to install a 8′ elevated walkway along Dayton Ave.

Elevated walkways are great – but 8′ of elevated, impervious walkway material and the removal of large groves of trees definitely runs the risk of exacerbating a runoff problem we’ve already seen happening on Dayton.  

One area which will see a high amount of tree removal is that very specific area (see below) between the WSDOT driveway/entrance and the southern fire hydrant.

Tree removal here would be an unfortunate move – because we know that this area responds particularly well in storm events (especially in that undisturbed stretch between the bench and the fire hydrant). Therefor our design team focused on visualizing a solution which could manage the inevitable increase of runoff caused by a walkway  – while also maximizing the soil retention area for the trees. Here is what we came up with.   

Tree Walk Proposal:

1. Reduce the 8′ proposed walkway to 5′. Cutting the walkway down by 3′ would reduce the runoff caused by the introduction of impervious materials/removal of trees. It would also still give the critical root zone (CRZ) separation from foot traffic. 

2. Investigate using structural soils, elevated walkways, and protective construction measures  – in various combinations, to create a healthy soil environment for current and future trees.

3. Add cutout walkway areas. Include stopping rest points with information signs to encourage pedestrians to share the space, while also taking time to appreciate the scenery.

4. Where trees are sparse (like the WSDOT entrance zone), establish new plantings which will help maintain the longterm carbon balance of the site (and Shoreline) as a whole. (Hint: maybe call it a ‘Carbon Garden’?).  

5. Add rain garden ‘trenches’ to help manage Dayton’s water surplus during the winter months – and stop ‘the River’ from taking over the bike lane. 

Below are some graphics of our vision. We look forward to hearing what you think!