The Smith Truss Covered Bridge

The Smith Truss Covered Bridge

Robert W. Smith (1834-1898) was the son of an Ohio cabinet maker. On July 16th, 1867, he received a patent for a design with compression members at 45 degrees and tension members at 65 degrees. His goal was to reduce the amount of timber in the structure. He moved to Toledo, Ohio that year and organized the R.W. Smith & Company partnership. Smith received a second bridge patent in 1869 for roofing and lateral-bracing systems. He continued to modify and refine his designs but did not apply for additional patents. As a result, many Smith truss bridges do not exactly follow the patented designs. In 1870, the company's name was changed to Smith Bridge Company. Over time the company transitioned to the exclusive fabrication of metal bridges. The variety of Smith trusses makes categorizing them somewhat challenging. Research into the topic has generated a revision to the descriptions previously used. These revised descriptions are intended to follow the designs and drawings used by Smith when promoting his bridges.

Single web - this design resembles a series of inverted Vs. These structures were incorrectly identified as Warren trusses in previous editions. Three examples remain in Ohio.

Double web - there are two styles of the double web design. The second web was a copy of the first although the truss started at a different location within the pattern. Formerly referred to as Type 3.

Type A (symmetrical) - the second web is placed such that the tension members from one web are halfway between those of the other web giving the appearance of Xs.

Type B (asymmetrical) - this is seen as continuous Xs, but a close inspection will show that the tension members are not symmetrical, that there is one more towards one end than the other.

Triple web - a third web added for additional strength in longer spans. The design of the third web is a duplicate of the first. Formerly referred to as Type 4.