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Preservation of Covered Bridges

 

Truss Types

Last updated April 1, 2015

This page lists the various types of trusses listed in the World Guide to Covered Bridges.

trusses
Figure 1.left. Kingpost.
Figure 1.right. Queenpost.
Figure 2.Multiple Kingpost. With odd number of panels, the center panel is open or has crossed braces as shown by the dashed lines.
Figure 3.Town Lattice, disposition illustrated on 1820 patent drawing shown (only two chords indicated thereupon; one at the top and one at the bottom of the truss.) For railroads and many highways, two secondary chords were made use of for additional strength.
trusses
Figure 4.Burr Arch. A multiple Kingpost truss with one or two arches added on inside and outside. Ends of the arch extend below the lower chord and rest on the abutments.
Figure 5.Arch, tied (shown), or two hinged (not illustrated), the latter where the ends of the arch are seated on the faces of the abutments, the present drawing indicating various arrangements of suspension: verticals, diagonals, and crossed X bracing.
Figure 6.Long, with 3 wood diagonals and double timber posts in each panel.
Figure 7.Paddleford. Ends of counterbraces cross both the kingposts and the chords. An inside arch is often added.
Figure 8.Howe, usual type. Three wood diagonals and 2 or 3 iron rod verticals.
Figure 9.Howe, single type. Dashed lines are iron rods.
Figure 10.Howe, western type. Center panel sometimes open.
Figure 11.Haupt, 1839 patent. One remaining example: the Bunker Hill Covered Bridge in Catawba County, North Carolina.
Figure 12.Warren. Single system is in solid lines, double system with added timbers indicated by dashed lines.
Figure 13.Pratt, revised design. Teco-Pratt designs usually have triple timbers. The California design has wooden posts and 2 iron rods as diagonals, crossed in center panel.
Figure 14.Childs, 1846 patent. Diagonals are mortised to chords.
Figure 15.Brown, 1857 patent. Diagonals are mortised to chords.
trusses
Figure 16.Smith, type 2, 1869 patent. Type 3, no patent, reinforced as indicated by dashed center panel timbers.
Figure 17.Smith, type 4 improved, no patent.
Figure 18.Partridge, 1872 patent. Note addition of metal footplates. The seven surviving examples are modified designs with reinforcing rods and additional timber diagonals.
Figure 19.Post, 1863 patent. Iron rods indicated by dashed lines. The last example, the Bell’s Ford Bridge in Jackson County, Indiana, collapsed in 2006.
Figure 20.McCallum, 1867 patent. Posts are flared slightly. One example, the Powerscourt Bridge in Québec.
Figure 21.Suspension or Bowstring. Two examples, both in Ohio.
Figure 22.No Name Truss (neither a Haupt nor a modified Burr), two examples: Sayres Bridge in Orange County, Vermont, and Bath Village Bridge in Grafton County, New Hampshire.