A Thousand Words

From Beyond My Ken:

There was an interesting demonstration of the relative inadequacy of language during my trip to Governors Island last week. If you click on the photo above, which shows the Governors Island ferry tied up on the island as seen from the Manhattan shore, you can make out the configuration of the boat. There are four main occupied areas: the enclosed upper deck (pedestrian only), the unenclosed center of the lower deck (vehicles, bikes, and pedestrians), and the left and right* enclosed portions of the lower deck (pedestrians only).

The group I was with was told to go to the “outside left” area. “Left” is more or less unambiguous (* again) but “outside” has in this case two meanings. It could be a description of space (not inside) or it could be a direction (the outside lane). Given the configuration of the lower deck, the two meanings led to two different results: if outside was a description of space, then we’d be standing in the middle unenclosed space; if it was a direction, we’d be in the enclosed space. If the deck configuration were reversed, with the driving lanes at the far left and right (* yet again) edges, then it wouldn’t have mattered which sense of “outside” was intended because both would have led us to the same location.

Simply put, this is why we draw so much. The cliché that a picture is worth a thousand words is wrong when it comes to architecture and engineering: a single drawing is, for us, the equivalent to ten thousand words or more. Ambiguity in language trips us up at every turn if we attempt to describe buildings without illustrations. The simplest example I can think of: the concrete floors used on most modern steel-frame buildings are cast in place over corrugated steel deck. The deck has two “thicknesses,” the thickness of the steel sheet and the depth top-to-bottom of the squared-off sine wave of the corrugations. The first is well under 1/8 of an inch; the second is usually 1-1/2, 2, or 3 inches. The depth of the concrete slab is typically measured from its top surface to the highest point on the steel deck corrugations, and can vary from 2-1/2 to 4 inches or more. If I say to another structural engineer or to a contractor familiar with this item of work that I want “three inches of concrete slab on a three-inch 18-gage** deck” it’s clear as day that I mean a 6-inch thick floor. Conversations with various other parties over the years have made it clear to me that’s not actually clear as day to most people.

As an example, I want to see how many words it takes to describe the simplest ordinary steel beam connection, assuming that I’m allowed to use industry standard names for the various pieces.*** Here goes:

The W8x10 beam is to be attached at right angles to the W12x40 girder, with their tops flush, and both beams located in a horizontal plane and oriented with their webs vertical. The W8 is to have its top flange and the top of its web coped one inch deep and five inches long to fit around the W12’s top flange. The cope is to have a quarter-circle corner where the vertical and horizontal cuts meet. The W8 length is to be cut 1/8 inch short of the W12 web surface. A L4x4x1/4 connection angle, six inches long, is to be placed on either side of the W8 web, with one leg of each angle parallel to and against the W8 web and one leg parallel to and against the W12 web. The angles and the webs of the W8 and W12 are to be predrilled with 13/16-inch diameter bolt holes. The two holes in the W8 web are to be located three inches apart and centered on the beam depth; the four holes on the W12 are at the same distances from the top of the beams and located 2-1/2 inches on each side of the W8 web centerline. The holes in the angles match the location in the beam webs. All bolt holes are to receive 3/4-inch diameter ASTM A325 bolts with washers and nuts.

That’s 228 words to cover a detail that anyone involved with steel construction can draw in thirty seconds, and I’m not sure I covered everything. That’s a simple detail and I allowed myself the use of the jargon-like names. It boggles the mind to think of what the description of a complicated details would be like.

Finally, it turned out that I was supposed to stand in the enclosed area, outside in the open air but inside of the edge area of the boat.

* I know, I know, port and starboard. I’m no sailor.

** Believe it or not, I’ve simplified. I actually need to specify the type of corrugated deck, and that descriptor usually goes where the double asterisk is.

*** If I can’t use that level of jargon, just describing the geometry of a standard wide-flange beam might take me a thousand words.