Lidding I-5...or a 50/20 version?
Lidding I-5 through the Downtown core would be phenomenal—placemaking, addressing our dearth of park space, improving walkability, connecting neighborhoods, and potentially adding development capacity. This morning, the City's Office of Planning and Community Development presented a feasibility analysis for a series of lids from Denny to Madison to the Seattle Design Commission. This was funded by the Washington State Convention Center Addition's public benefit package.
The lid's billion-or-three cost is juuust a little daunting, even with varied funding sources. So here's a suggestion: Keep the big idea on the table, but ALSO study ways to accomplish much of the benefit at a fraction of the cost. Further, extend the analysis at least to Main on the south and Thomas on the north.
About the Concepts Presented
The study looked at multiple lid options from Denny to Madison, costing an estimated $855 million to $2.863 billion in 2019 dollars. The low-end version was for parks, and the high-end lid would be stronger to allow major buildings in some locations.
Some of the cost for the high figure would be recouped by selling development rights, but likely not enough to pay for the stronger lid. My own quick look suggests the cost difference would be substantial. This suggests the park-only concept, or a version with limited development, will have more chance of going forward. I suspect voters will like it more as well.
But even the park concept is a billion dollars for 11.5 acres of lid. While that seems reasonable vs. the cost of CBD land and the economic benefits could be substantial, will the average Lake City resident vote for even a good chunk of the total? The Seattle Commons lost 47-53 twice despite being about 4% and 2% of the per-acre cost in today's dollars in its two attempts. (Disclosure: I was on the Commons nonprofit and campaign staff.)
We could wait for I-5 to be rebuilt, as noted during the meeting. If so a lid could be incorporated more easily and affordably, much like the 520 and I-90 examples. But a rebuild is a big if, and could be decades away.
A 50/20 Approach
So let's also study concepts that can serve many of the same goals while costing less, and where a resulting wish list could be funded and built in much smaller increments. Maybe we can find a good scenario in the $200-300 million range.
For example, imagine a series of 30-50' wide crossings somewhere between "lid" and "skybridge." These could break up gaps where I-5 is a barrier, and add space at existing crossings. With good design they could serve as linear parks while letting pedestrians almost forget about the freeway. Some could become viewpoints. Retail (kiosks?) could be included in some spots.
A crossing at Harrison or Thomas would break up a 2/3-mile barrier, including a stair/elevator tower. Several overpasses from Denny to Yesler could be augmented with parallel spans to provide open space and reconnect neighborhoods. The north side of Denny lacks a sidewalk and could be a good option. A connection at South Main would break up another barrier and improve access to Yesler Terrace and Harborview. Maybe do three to five of these in total?
Some locations would coordinate with existing plans. Most notably, the Pike Pine Renaissance program anticipates making both one-way east of 8th to provide more room for pedestrians and bicyclists. Another 30-50' would greatly improve the psychological connection up the hill and provide some open space.
A basic skybridge might serve in a location or two instead, and should be studied. At least these would improve basic access across I-5.
And let's not forget the underpasses at Cherry and James. Cherry has the most room for creative improvements since its north side columns are well apart from the street. The freeway would give it an all-weather aspect.
Again, I love the idea of a big lid for many reasons. But let's look at options!