Sellwood Bridge

Sellwood Bridge
Posted by on July 14, 2015
Posted in: built projects, geomodeling, transportation

For my first assignment as an intern at Fat Pencil Studio I was tasked with building a model of the new Sellwood Bridge, currently sitting about 75% completed. Documentation was limited to one invaluable elevation drawing, a west side interchange diagram, a couple of renderings of the designer’s own model, and a variety of photographs of various stages of construction. No blueprints, no dimensions other than a breakdown of the roadway cross section at its narrowest point and a few length values on the elevation.

This is the largest structure I’ve modeled and it is truly immense. Until one has stood under the structure (which I did at one point to collect additional photographs), it can be difficult to grasp the scale of this collection of massive concrete and steel components. None of them was particularly difficult to model, as the limited budget of the bridge project has resulted in simple, almost spartan design elements, but determining the size of them and how they relate to one another in three dimensions became an exercise in estimation, deduction, and outright speculation. Units of measurement when modeling by eye from photographs tend toward the unconventional: the height of a construction worker, the number of 4×8 sheets of plywood impressed on the face of a concrete casting.

The most time-consuming aspect of the project was evaluating the proportions of all elements as they relate to one another in the model and how they compare to the photographic evidence. This required continual fine tuning which was punctuated by mini-revelations. For example, it was a discussion with a representative of the construction company (sent to inquire about my activities while I was crawling around the site taking notes and photographs) that settled the crucial uncertainty of whether the middle pair of arches do in fact flare out to accommodate the addition of two lanes on the west end of the roadway. This confirmation allowed the modeling of the supporting structure to progress smoothly and with much greater confidence.

After I tried and failed to talk the construction company out of some blueprints, Joshua assured me that this level of precision would not be necessary and that working without known dimensions would be good practice. Indeed, the lesson of this introductory assignment for me, the one member of the team unpracticed at modeling real life entities by eye, was that to do so quickly and accurately, one must develop a keen perception of relationships between objects and learn to seek and trust information gleaned from less-than-obvious sources. It requires a bit of faith and willingness to let go of exactitude and embrace a looser harmony.

Soaring above Portland's new youngest bridge

Looking to the east side from the new Sellwood bridge pedestrian lane

Sellwood bridge model in Google Earth with construction material still present

Massive concrete footings dwarf a personal watercraft

North side of the Sellwood bridge at sunset

About Dominic

Dominic Blaszak was an intern at Fat Pencil Studio in 2015.