Historic Bridge Styles

Bridge #28, Parke County.

Structures designed and erected during the 19th century are becoming increasingly rare. Bridges are a unique offshoot of architecture and possess their own associated terms, components and styles. 

As the number of metal bridges decline, it become more important to protect the resources we have. Those projects that affect bridges, where state or federal funds are used, have a review process through the DHPA. In an effort to assist, those interested in protecting bridges and so that everyone understands the reason for assessing bridges in various ways, the DHPA has created a guide for the assessment of metal bridges.

Sometimes, though, bridges cannot be saved in their original location. In response to this, the Federal Highway Administration and the Indiana Department of Transportation have joined forces to preserve some of Indiana’s historic bridges. The two agencies have created the “Historic Bridge Marketing Program” -- an online database of iron, stone, and concrete bridges that are facing future bypassing or demolition. The intention is to locate parties who would be interested in either maintaining or relocating the bridge, so the resource is not lost.

Terminology

Types

Bridge Truss Styles - Architectural Guide

• King Post

  
  (Wood)
  Drawing: Historic American Engineering Record

  A traditional truss type with its origins in the Middle Ages.

  Length: 20-60 feet (6-18 meters)

• Queen Post

  
  (Wood)
  Drawing: Historic American Engineering Record

  A lengthened version of the King Post.

  Length: 20-80 feet (6-24 meters)

• Pratt

  
  1844-20th century
  Drawing: Historic American Engineering Record

  Diagonals in tension, verticals in compression (except for hip verticals adjacent to the inclined end posts).

  Length: 25-150 feet (8-45 meters)

  Click to enlarge

  
  County Bridge 40
  Crawford County, IN

  
  County Bridge 91 (Demolished)
  Crawford County, IN

• Pratt Half-Hip

  
  Late 19th century - Early 20th century
  Drawing: Historic American Engineering Record

  A Pratt with inclined end posts that do not horizontally extend the length of a full panel.

  Length: 30-150 feet (9-45 meters)

• Double Intersection Pratt

  
  (Whipple, Whipple-Murphy, Linville)
  1847 - 20th century
  Drawing: Historic American Engineering Record

  An inclined end post Pratt with diagonals that extend across two panels.

  Length: 70-300 feet (21-90 meters)

  Click to enlarge

  
  County Bridge 541
  Allen County, IN

  
  County Bridge 159
  Dearborn County, IN

• Burr Arch Truss

  
  (Wood)
  1804 - late 19th century
  Drawing: Historic American Engineering Record

  Combination of a wooden arch with a multiple King Post (Arch also combined with later wooden trusses). This truss type is often used in the construction of covered bridges in Indiana.

  Length: 50-175 feet (15-50 meters)

• Town Lattice

  
  (Wood)
  1820 - late 19th century
  Drawing: Historic American Engineering Record

  A system of cross-hatched wooden diagonals with no verticals.

  Length: 50-220 feet (15-66 meters)

• Truss Leg Bedstand

  
  Late 19th century - early 20th century
  Drawing: Historic American Engineering Record

  A Pratt with vertical end posts imbedded in their foundations.

  Length: 30-100 feet (9-30 meters)

  Click to enlarge

  
  County Bridge 181 (Demolished)
  Clay County, IN

• Parker

  
  Mid to late 19th century - 20th century
  Drawing: Historic American Engineering Record

  A Pratt with a polygonal top chord.

  Length: 40-200 feet (12-60 meters)

  Click to enlarge

  
  County Bridge 3346
  Tippecanoe County, IN

• Baltimore (Petit)

  
  1871 - Early 20th century
  Drawing: Historic American Engineering Record

  A. A Pratt with sub-struts.

  B. A Pratt with sub-ties.

  Length: 250-600 feet (75-180 meters)

• Pennsylvania (Petit)

  
  1875 - Early 20th century
  Drawing: Historic American Engineering Record

  A. A Parker with sub-struts.

  B. A Parker with sub-ties.

  Length: 250-600 feet (75-180 meters)

  Click to enlarge

  
  County Bridge 100 (Demolished)
  Allen County, IN

  
  New York Central Railroad Bridge
  Clark County, IN

• Lenticular (Parabolic)

  
  1878 - early 20th century
  Drawing: Historic American Engineering Record

  A Pratt with both top and bottom chords parabolically curved over their entire length.

  Length: 150-400 feet (45-120 meters)

• Warren

  
  1848 - 20th century
  Drawing: Historic American Engineering Record

  Triangular in outline, the diagonals carry both compressive and tensile forces.  A "true" Warren truss has equilateral triangles.

  Length: 50-400 feet (15-120 meters)

  Click to enlarge

  
  County Bridge 137 (Demolished)
  Benton County, IN

  
  County Bridge 216 (Demolished)
  Hendricks County, IN

• Warren with Verticals

  
  mid 19th - 20th century
  Drawing: Historic American Engineering Record

  Diagonals carry both compressive and tensile forces.  Verticals serve as bracing for triangular web system.

  Length: 50-400 feet (15-120 meters)

  Click to Enlarge

  
  County Bridge 398
  Gibson County, IN

  
  County Bridge 64 (Demolished)
  Carroll County, IN

• Double Intersection Warren

  
  (Lattice)
  mid 19th - 20th century
  Drawing: Historic American Engineering Record

  Structure is indeterminant.  Members act in both compression and tension.  Two triangular web systems are superimposed upon each other with or without verticals.

  Length: 75-400 feet (23-120 meters)

  Click to enlarge

  

  Railroad Bridge
  Tippecanoe County, IN

• Pegram

  
  1887 - early 20th century
  Drawing: Historic American Engineering Record

  A hybrid between the Warren and Parker trusses, upper chords are all of equal length.

  Length: 150-650 feet (45-195 meters)

• Howe

  
  (wood, verticals of metal)
  1840-20th century
  Drawing: Historic American Engineering Record

  Diagonals in compression, verticals in tension.

  Length: 30-150 feet (9-45 meters)

• Bowstring Arch-Truss

  
  1840-late 19th century
  Drawing: Historic American Engineering Record

  A tied arch with the diagonals serving as bracing and the verticals supporting the deck.

  Length: 70-175 feet (21-50 meters)

  Click to enlarge

  
  
  County Bridge 52
  Miami County, IN

• Wichert

  

  1932 - mid-late 20th century
  Drawing: Historic American Engineering Record

  Characterized by a pin connected rhomboidal structural arrangement over the piers. Truss is continuous over piers.

  Length: 400-1000 feet (122-305 meters)

• Camelback

  

  Late 19th - 20th century
  Drawing: Historic American Engineering Record

  A Parker with a polygonal top chord of exactly five slopes.

  Length: 100-300 feet (30-90 meters)

• Camelback with Subdivided Panels

  

  Late 19th - 20th century
  Drawing: Historic American Engineering Record

  A Pennsylvania truss with a polygonal top chord of exactly five slopes.

  Length: 100-300 feet (30-90 meters)

• Kellogg

  

  Late 19th century
  Drawing: Historic American Engineering Record

  A variation of the Pratt with additional diagonals running from upper chord panel points to the center of the lower chords.

  Length: 75-150 feet (23-50 meters)

• Waddell "A"

  

  Late 19th - early 20th century
  Drawing: Historic American Engineering Record

  Expanded version of the King Post truss. Usually made of metal.

  Length: 25-75 feet (8-23 meters)

• Griener

  

  1894 - early 20th century
  Drawing: Historic American Engineering Record

  Pratt truss with the diagonals replaced by an inverted bowstring truss.

  Length: 75-250 feet (23-75 meters)

• Schwedler

  

  Late 19th century
  Drawing: Historic American Engineering Record

  A double intersection Pratt positioned in the center of a Parker.

  Length: 100-300 feet (30-90 meters)

• K-Truss

  

  Early 20th century
  Drawing: Historic American Engineering Record

  So called because of the distinctive outline of the structural members.

  Length: 200-800 feet (60-240 meters)

• Post

  

  1865-late 19th century
  Drawing: Historic American Engineering Record

  A hybrid between the Warren and the Double Intersection Pratt.

  Length: 100-300 feet (30-90 meters)

• Bollman

  

  (Rare)
  1852-Mid to late 19th century
  Drawing: Historic American Engineering Rec

  Verticals in compression, diagonals in tension. Run from end posts to every panel point.

  Length: 75-100 feet (23-30 meters)

• Fink

  

  (rare)
  1851-late 19th century
  Drawing: Historic American Engineering Record

  Verticals in compression, diagonals in tension. Longest diagonals run from end posts to center panel points.

  Length: 75-100 feet (23-45 meters)

• Stearns

  

  1892-early 20th century
  Drawing: Historic American Engineering Record

  Simplification of Fink truss with verticals omitted at alternate panel points.

  Length: 50-200 feet (15-60 meters)