That's a lot of shingles.
The bridge is supported entirely by two trusses based off the design in the Howe patent. It's built of timber and iron rods and an Auxiliary Burr Arch which is bolted to the trusses and connects to the face of the abutments. All the weight of the bridge rests on these abutments. The wood is Douglas fir and the 27,000 shingles are made of sugar pine.
The bridge is supported entirely by two trusses based off the design in the Howe patent. It's built of timber and iron rods and an Auxiliary Burr Arch which is bolted to the trusses and connects to the face of the abutments. All the weight of the bridge rests on these abutments. The wood is Douglas fir and the 27,000 shingles are made of sugar pine.