This image shows a concrete pour for 520 just east of Foster Island in the fall of 1961. After this area was dredged, barges brought equipment and materials to the work site as seen in the foreground. Workers are guiding wet concrete into the wooden formwork of a beam across a row of columns extending above the water. When finished, these “column bents” will support long-spanning girders that in turn support the roadway.
Many millions of people have driven across this piece of concrete cast into the Arboretum wetlands. Significantly fewer people have rented a canoe and paddled under it.