December 16, 2011

Last week we noted the breaking of some common main street "rules" on Sedalia's wonderful Ohio Avenue. The absence of street trees is a big one, though architectural photographers don't miss them. We also noted that the retail sidewalk is a bit narrow, only 10 feet where the shops are. I paced off the roadbed at 42 feet, and the two travel lanes are each 12 feet. That's normally too wide for a 20 mph target speed, which is the fastest you should be designing for in the T5 zone where there are a lot of pedestrians. Yet the street space instantly felt comfortable, and traffic moved slowly. Let's take a look at why it works.

The first image is a panorama made up of four separate images shot from a bench in the excellent courthouse square. The street is actually straight where the tree trunk is, but I'm still learning how to use Photomerge; see last week's post for a closer view in front of the courthouse.

Next, Ohio Avenue continues downhill after the Hotel Bothwell, which is the 7-story anchor building partially visible on the right. The street space appears closed off into an "outdoor room" because of a slight deflection a block later. The third image shows the view uphill from below; although there is no deflection at the top, the hill creates a visual enclosure before the street levels off at the hotel. (The hotel corner sign is on the right in the first of this pair, on the left in the second.)

All photographs ©2011 Sandy Sorlien 

Several things slow car traffic: the hill (because drivers can't see everything beyond it), the deflection (same reason), the parked cars (because a person may suddenly step out from them, or open a door) and the contrasting crosswalk paving. The paving was pretty spiffy for a place where every fifth storefront was vacant. That's a common condition these days - sad retail frontages belying hopeful new curbs, crosswalks and streetlights. 

The hill and deflection also work in concert with the block faces to create spatial containment – a comfortable outdoor room. The next image has green lines drawn on it to indicate the proportion of the right-of-way (ROW) to the height of the block faces. Traditional wisdom holds that the ideal mixed-use street is 1:1, and this one is just slightly wider than that where the three-story buildings are. The bare minimum for spatial definition would be 1:3 height to width before it all falls apart, but in the higher Transect habitats where you want high pedestrian activity, the tighter ratio is more effective. On a ROW not much wider than 60 feet (this one is 62), the shopfronts can be read easily from both sides of the thoroughfare.

For all the reasons stated, it feels comfortable to cross such a street, and to be in its space. Visitors to your downtown, while they can see the sky and enjoy the daylight, are really in a spatial container for successful street life. The container can't be too shallow, or psychologically they'll fly away; more to the point, they'll prefer to drive. And if they prefer to drive, they're going to the mall.

Next week: awnings, architecture, blocks, glazing, lights, benches and signs.