What about a Tunnel Effect?
One of the things about the now-abandoned Mirror Pond site for a Police Station that occasioned criticism was the prospect of a "tunnel effect" Commercial Street between the proposed Police Station and the South Block apartments.
|Abandoned Mirror Pond Civic Center concept from June 2013|
Here is a magnificent "tunnel effect"!Beautiful! Hermoso!— Eduardo Amorim (@dudu_amorim) March 21, 2015
Avenida de la Constitución
Salem should be so lucky to have something like this!
Traditional, walkable urbanism is grounded in figural space. It believes that the shape of the spaces between buildings is what matters.— Jeff Speck (@JeffSpeckAICP) February 29, 2016
“If a dinner party is held at narrow tables, a festive mood quickly catches on because everyone can talk in several directions.”— Jeff Speck (@JeffSpeckAICP) March 1, 2016
Large public spaces can often end up offering less of an amenity than smaller ones, especially if the buildings surrounding them aren’t tall— Jeff Speck (@JeffSpeckAICP) March 1, 2016
|1:2 and 1:3 building-to-street enclosure ratios|
(Institute of Transportation Engineers)
The threshold when pedestrians first perceive enclosure is a 1:4 ratio of building height to thoroughfare width—typical of low-density environments. In denser urban contexts, height-to-width ratios between 1:3 and 1:2 create an appropriate enclosure on a thoroughfare.Density and ratio are a relative things here. You'll note that example from Seville has a ratio closer to 1:1 or maybe even 2:1 than to 1:2 or 1:3.
It speaks to Speck's point about the dinner party. Looking at pre-auto and European examples, contemporary urbanists often argue ratios larger than 1:1 are appropriate, lively, and pleasant.
A Civic Center Site was an Opportunity, but not Best Tunnel
The Civic Center concept had some advantages, but at the same time it wasn't easy to rally behind with any enthusiasm.
First, it is clear that Commercial Street at the Civic Center is not nearly so civilized as the street in Seville. So that obviously isn't something we could have duplicated there. (So it's not like criticism about a tunnel there is 100% wrong. The lack of sidewalk-scaled interest along the parking garage at South Block seriously detracts from the possibilities for a stimulating street and building enclosure here. Pairing that with a Police Station doesn't inherently point to a lively, walkable sense of enclosure.)
But it also seems like Peace Plaza is a bad, even broken, public space. The plaza between the Library and City Hall is another "tunnel" and suffers from blank walls, poor connectivity on the edges, and insufficient other adjacency to provide additional activity. It's a dead space most of the time.
A new Police Station and set of seismic updates was an opportunity to reconfigure the Civic Center. The proposed building you see at top doesn't do that, and that proposal for a new Police Station at the Civic Center didn't grapple deeply enough with rethinking the way the Civic Center works. There might have been an opportunity for a new vision at the Civic Center that could have commanded more enthusiasm and support.
|The O'Brien collection is bigger than you think|
(SCI student study from five years ago.
I don't want to go back and re-litigate the proposal for a Police Station at the Civic Center. I think that claims it was best are overblown and claims it was worst were overblown. Not using that existing land at the Civic Center is a renunciation, it's true, and there are very real opportunity costs about the O'Brien site. But the renunciation is not a grave one. We'll manage just fine with the O'Brien site.
Mid-Rise and Enclosure
Instead, the I want to suggest we think more about the way we used a "tunnel effect" to argue against the Civic Center. As we'll have similar arguments in the future, "tunnel effects" ought to be something we think more about in a critical way.
An allergy to mid-rise forms and an embrace of low enclosure ratios goes hand-in-hand with excessive autoism. If we want supremely walkable places, we need to be open to some higher forms of mid-rise.
|Pioneer Trust Bank: Mid-rise perfectly scaled here|
Only one building might actually dominate. The great exception in height, the Livesley building, sticks out, and Salem doesn't need any more towers like that.
Going down in scale, most of our two-story downtown is too small for our 99-foot street widths, in fact. This contributes at least a little to the zoominess of downtown traffic.
Here is it easy to see how this notion of "enclosure" also scales for residential streets and calms traffic. The principle for downtown is the same. Narrowing the perceived width of streets is a sound move for better walking and biking.Great graphic by @TransPsychology we need to design our roads for the speed and behavior we desire pic.twitter.com/Tqa3IRl5I8— Darren Proulx (@dnproulx) October 31, 2015
We sure could use a greater number of modest mid-rise buildings, and we should embrace well-designed corridors that offer the aesthetic experience of enclosure.
Over-simple arguments against "tunnel effects" will doom our efforts for more walkable spaces and buildings.