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Historic Bridge Categorization and Description Table

The bridge types shown in the table below are included on the Historic Bridge Survey compiled by the Illinois Department of Transportation. The table provides information in regard to the manner in which specific bridge types are grouped within the Historic Bridge Survey, as well as a description of each bridge type included. To be included among the structures of the Historic Bridge Survey, the structure must be at least 50 years old and of historic significance.

Numerical Coding

Bridge Type

Bridge Type Division

Bridge Type Description

Group

Period of Construction

101

Concrete

 

-

 

Slab

1

Early Examples 1916 and Prior

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure composed of a cast-in-place concrete slab strengthened through the use of steel or iron reinforcement bars.

2

Middle Examples

 

1917 to 1926

3

Late Examples

1927 and Later

 

103

Concrete

 

-

 

Deck Girder

 

(Load Path Non-Redundant System)

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure consist of two cast-in-place reinforced concrete beams, with one located near each side of the superstructure below the portion of the superstructure that is in direct contact with traffic loads.

 

104

Concrete

 

-

 

Tee Beam

1

Early Examples 1922 and Prior

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure consist of multiple (three or more) cast-in-place reinforced concrete beams located below the portion of the superstructure that is in direct contact with traffic loads.

2

Middle Examples 1923 to 1929

3

Late Examples 1930 and Later

 

107

Concrete

 

-

 

Rigid Frame

1

Early Examples 1934 and Prior

A one span bridge having a superstructure composed of a cast-in-place concrete slab strengthened through the use of steel or iron reinforcement bars.  The superstructure is constructed integrally with the upper portion of the substructure in a manner that ensures that the connection between the superstructure and substructure will function in a rigid manner to support traffic loads.

 

 

2

Late Examples 1935 and Later

 

111

Concrete

 

-

 

Arch-Deck, Filled Spandrel

1

Early Examples 1916 and Prior

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure composed of cast-in-place concrete and strengthened through the use of steel or iron reinforcement bars.  The main load carrying member of the superstructure consists of an arched slab that bears on and thrust against the lower portion of substructure units located at each span end.  A vertical concrete wall is constructed on each side of the arched slab for the entire distance between substructure units.  The area above the arched slab and between the vertical walls is filled with earthen material.  A pavement is constructed on top of the fill material to carry traffic.

2

Middle Examples 1917 to 1926

3

Late Examples 1927 and Later

 

112

Concrete

 

-

 

Arch, Thru

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of non-integral spans, having a superstructure composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure are arches located adjacent to each side of the superstructure.  The arches extend above the level of the surface of the bridge directly in contact with traffic.

 

124

Concrete

 

-

 

Thru Girder

1

Early Examples 1920 and Prior

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure consist of large beams located on each side of the superstructure.  The beams extend above the level of the surface of the bridge directly in contact with traffic.

2

Middle Examples 1921 to 1927

3

Late Examples 1928 and Later

 

125

Concrete

 

-

 

Arch-Deck, Open Spandrel

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of non-integral spans, having a superstructure composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure consist of arches or an arched slab located below the portion of the bridge in direct contact with traffic.

 

201

Concrete Continuous

 

-

 

Slab

1

Historically Significant and 50 years or more in age

A multi-span span bridge having a superstructure that is uninterrupted over interior supports and composed of a cast-in-place concrete slab strengthened through the use of steel or iron reinforcement bars.

 

203

Concrete Continuous

 

-

 

Deck Girder

 

(Load Path Non-Redundant System)

1

Historically Significant and 50 years or more in age

A multi-span span bridge having a superstructure that is uninterrupted over interior supports and composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure consist of two cast-in-place reinforced concrete beams located below the portion of the superstructure that is in direct contact with traffic loads.

 

204

Concrete Continuous

 

-

 

Tee Beam

1

Historically Significant and 50 years or more in age

A multi-span span bridge having a superstructure that is uninterrupted over interior supports and composed of cast-in-place concrete strengthened through the use of steel or iron reinforcement bars.  The main load carrying members of the superstructure consist of multiple (three or more) cast-in-place reinforced concrete beams located below the portion of the superstructure that is in direct contact with traffic loads.

 

302

Steel

 

-

 

Multi Beam

1

1916 and Prior

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of multiple (three or more) plate girders or beams located below the portion of the superstructure that is in direct contact with traffic loads.

2

1917 and Later

 

303

Steel

 

-

 

Deck Girder

 

(Load Path Non-Redundant System)

1

1916 and Prior

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of two plate girders or two beams, with one located near each side of the superstructure below the portion of the superstructure that is in direct contact with traffic loads.

2

1917 and Later

 

305

Steel

 

-

 

Box Beam, Multiple Adjacent

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of multiple (two or more) box beams located below the portion of the superstructure that is in direct contact with traffic loads.

 

307

Steel

 

-

 

Rigid Frame

1

Historically Significant and 50 years or more in age

A one span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of multiple (three or more) lines of plate girders or beams located below the portion of the superstructure that is in direct contact with traffic loads.  The load carrying members are constructed integrally with the upper portion of steel substructure elements in a manner that ensures that the connection between the superstructure and substructure will function in a rigid manner to support traffic loads.

 

 

309

Steel

 

-

 

Truss, Deck

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of two steel trusses located below the portion of the superstructure that is in direct contact with traffic.  One truss is located below the superstructure near each side of the superstructure.  A specific truss type is not specified for this Numerical Coding of “309”.  (See Truss Type examples)

 

311

Steel

 

-

 

Arch, Deck, Filled Spandrel

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of non-integral spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying member of the superstructure consists of steel arched span elements that bears on and thrust against the lower portion of substructure units located at each span end.  A steel vertical wall is constructed on each side of the arched span elements for the entire distance between substructure units, and the area above the steel arched span elements and between the vertical walls is filled with earthen material.  A pavement is constructed on top of the fill material to carry traffic.

 

312

Steel

 

-

 

Arch, Thru

1

1904 and Prior

A one span bridge, or a bridge consisting of a series of non-integral spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of steel arches located adjacent to each side of the superstructure.  The arches extend above the level of the surface of the bridge directly in contact with traffic.

2

1905 and Later

 

313

Steel

 

-

 

Suspension

1

Historically Significant and 50 years or more in age

A bridge typically having one span and a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of steel cables that are draped over support towers at the ends of the span and anchored in foundations that are remote from the span.  The portion of the bridge carrying traffic is supported by vertical members that are hung intermittently from the cables.

 

315

Steel

 

-

 

Movable, Lift

1

Historically Significant and 50 years or more in age

A one span bridge, typically constructed over a navigable waterway, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members are typically steel trusses.  The entire bridge span is periodically moved in a vertical direction to allow for the passage of shipping using the navigable waterway under the bridge.  The vertical movement is accomplished by lifting both ends of the span simultaneously at lift-towers located at the ends of the span.

 

316

Steel

 

-

 

Movable, Bascule

1

Early Examples

 

1912 and Earlier

A one span bridge, typically constructed over a navigable waterway, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members are typically steel trusses or plate girders.  The bridge span is periodically moved in a vertical direction to allow for the passage of shipping using the navigable waterway under the bridge.  A vertical movement of the span is accomplished by a pivoting/rotating action of the main load carrying members at one or both of the supports located at the ends of the bridge span.  The pivoting/rotating action moves the free end of the main load carrying members upward to allow for the passage of shipping.

2

Middle Examples

 

1913 to 1926

3

Late Examples

 

1927 and Later

 

324

Steel

 

-

 

Thru Girder

1

Early Examples

 

1916 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of plate girders or beams located on each side of the superstructure.  The beams extend above the level of the surface of the bridge directly in contact with traffic.

2

Late Examples

 

1917

 

325

Steel

 

-

 

Arch, Deck, Open Spandrel

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of non-integral spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of arches located below the portion of the bridge in direct contact with traffic.

 

330

Steel

 

-

 

Pony Truss, Pratt, Eyebar

1

Early Examples

 

1913 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of steel eyebars with pin connections at the joints.  (See Truss Type examples.)

2

Middle Examples  1914 to 1925

3

Late Examples

 

1926 and Later

 

331

Steel

 

-

 

Pony Truss, Pratt, Riveted

1

Early Examples

 

1913 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of rolled steel elements with riveted gusset plate connections at the joints.  (See Truss Type examples.)

2

 

 

Middle Examples

 

1914 to 1925

 

 

3

Late Examples

 

1926 and Later

 

332

Steel

 

-

 

Pony Truss, Pratt Half-hip

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  (See Truss Type examples.)

 

333

Steel

 

-

 

Pony Truss, Leg Bedstead, Eyebar

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of steel eyebars with pin connection at the joints.  (See Truss Type examples.)

 

335

Steel

 

-

 

Pony Truss, Warren

1

Early Examples

 

1927 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  (See Truss Type examples.)

2

Late Examples

 

1928 and Later

 

336

Steel

 

-

 

Pony Truss, Modified Warren

1

1920 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  (See Truss Type examples.)

2

1921 and Later

 

337

Steel

 

-

 

Pony Truss, Double Intersecting Warren

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  (See Truss Type examples.)

 

338

Steel

 

-

 

Pony Truss, King Post or Queen Post

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are not connected to each other by bracing elements.  (See Truss Type examples.)

 

350

Steel

 

-

 

Thru Truss, Pratt Eyebar

1

Early Examples

 

1915 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of steel eyebars with pin connections at the joints.  (See Truss Type examples.)

2

Middle Examples

 

1916 to 1925

2

Late Examples

 

1926 and Later

 

351

Steel

 

-

 

Thru Truss, Pratt Riveted

1

Early Examples

 

1915 and Earlier

 

 

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of rolled steel elements with riveted gusset plate connections at the joints.  (See Truss Type examples.)

2

Middle Examples

 

1916 to 1925

3

Late Examples

 

1926 and Later

 

352

Steel

 

-

 

Thru Truss, Parker Eyebar

1

Early Examples

 

1917 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of steel eyebars with pin connections at the joints.  (See Truss Type examples.)

2

Late Examples

 

1918 and Later

 

353

Steel

 

-

 

Thru Truss, Parker Riveted

1

Early Examples

 

1917 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of rolled steel elements with riveted gusset plate connections at the joints.  (See Truss Type examples.)

2

Late Examples

 

1918 and Later

 

354

Steel

 

-

 

Thru Truss, Camelback Eyebar

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of steel eyebars with pin connections at the joints.  (See Truss Type examples.)

 

356

Steel

 

-

 

Thru Truss, Double Intersecting Pratt (Whipple)

1

Early Examples

 

1905 and Earlier

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  (See Truss Type examples.)

2

Late Examples

 

1906 and Later

 

357

Steel

 

-

 

Thru Truss, Pennsylvania (Petit)

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  (See Truss Type examples.)

 

361

Steel

 

-

 

Deck Truss, Pratt, Riveted

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses are placed below the portion of the superstructure that is in direct contact with traffic, and the bottom of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of rolled steel elements with riveted gusset plate connections at the joints.  (See Truss Type examples.)

 

370

Steel

 

-

 

Other Unclassified Trusses

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carry members consist of steel trusses located adjacent to each side of the superstructure.  The trusses are placed above the portion of the superstructure that is in direct contact with traffic.  The arrangement of the individual elements of the trusses do not match any of the commonly used truss types.  (See Truss Type examples.)

 

 

 

402

Steel

 

Continuous

 

-

 

Multi Beam

1

Early Examples

 

1916 and Earlier

A multi-span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of multiple (three or more) plate girders or beams located below the portion of the superstructure that is in direct contact with traffic loads.  The plate girders or beams continue uninterrupted over the substructure units supporting the middle-portion of the bridge.

2

Middle Examples

 

1917 to 1926

3

Late Examples

 

1927 and Later

 

403

Steel Continuous

 

-

 

Deck Girder (Load Path Non-Redundant System)

1

Historically Significant and 50 years or more in age

A multi-span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of two plate girders or two beams, with one located near each side of the superstructure below the portion of the superstructure that is in direct contact with traffic loads.  The plate girders or beams continue uninterrupted over the substructure units supporting the middle-portion of the bridge.

 

408

Steel Continuous

 

-

 

Orthotropic

1

Historically Significant and 50 years or more in age

A multi-span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members typically consist of welded girders located below the portion of the superstructure that is in direct contact with traffic loads.  A structural plate is attached to the top of the welded girders to function as a portion of the main load carrying member and to directly support traffic loads.  The welded girders and structural plate continue uninterrupted over the substructure units supporting the middle-portion of the bridge.

 

412

Steel Continuous

 

-

 

Arch, Thru

1

Historically Significant and 50 years or more in age

A multi-span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of steel arches located adjacent to each side of the superstructure.  The arches extend above the level of the surface of the bridge directly in contact with traffic.  The arches continue uninterrupted over the substructure units supporting the middle-portion of the bridge.

 

413

Steel Continuous

 

-

 

Suspension

1

Historically Significant and 50 years or more in age

A bridge typically having three spans and a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of steel cables that are draped over intermediate support towers and anchored at abutments.  The portion of the bridge carrying traffic is supported by vertical members that are hung intermittently from the cables.  The load carrying element of the bridge directly carrying traffic continues uninterrupted for the entire length of the multi-span bridge.

 

414

Steel Continuous

 

-

 

Cable Stayed

1

Historically Significant and 50 years or more in age

A multi-span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members of the superstructure consist of steel cables that are anchored in both the upper portion of intermediate support towers and the portion of the bridge that directly carries traffic loads.  The load carrying element of the bridge directly carrying traffic continues uninterrupted for the entire length of the multi-span bridge.

 

417

Steel

 

-

 

Movable, Swing

1

Historically Significant and 50 years or more in age

A two span bridge, typically constructed over a navigable waterway, having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members are typically steel trusses.  A horizontal movement of the spans is accomplished by a pivoting/rotating action of the main load carrying members at a middle support pier.  The pivoting/rotating action moves the free ends of the main load carrying members laterally to allow for the passage of shipping on one or both sides of the middle pier.

 

458

Steel

 

-

 

Thru Truss, Continuous

1

Historically Significant and 50 years or more in age

A multi-span bridge having a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The truss elements continue uninterrupted over the substructure units supporting the middle-portion of the bridge.

 

459

Steel

 

-

 

Thru Truss, Cantilever (Suspended Span)

1

Historically Significant and 50 years or more in age

A bridge typically having three spans and a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The truss elements continue uninterrupted over the substructure units supporting the middle-portion of the bridge to a point approximately one quarter of the way across the center span.  The portion of the bridge extending from the substructure units to the termination points in the center span are referred to as the cantilevers.  A suspended span is supported by the ends of the cantilevers within the middle part of the center span.

 

464

Steel

 

-

 

Deck Truss, Cantilever (Suspended Span)

1

Historically Significant and 50 years or more in age

A bridge typically having three spans and a superstructure which utilizes steel as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses are placed below the portion of the superstructure that is in direct contact with traffic, and the bottom of the trusses are connected to each other by bracing elements.  The truss elements continue uninterrupted over the substructure units supporting the middle-portion of the bridge to a point approximately one quarter of the way across the center span.  The portion of the bridge from the substructure units to the termination points in the center span are referred to as the cantilevers.  A suspended span is supported by the ends of the cantilevers within the middle part of the center span.

 

500

Prestressed Concrete

 

-

 

“Other”

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes concrete and prestressed wire strands in the manufacture of prefabricated main load carrying members, or the construction of main load carrying members in the field.  Prestressed wire strands may be either pre-tensioned or post-tensioned.

 

502

Prestressed Concrete

 

-

 

Multi Beam

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes concrete and prestressed wire strands in the manufacture of prefabricated main load carrying members.  The main load carrying members consist of multiple (three or more) prefabricated beams located below the portion of the superstructure that is in direct contact with traffic loads.  Prestressed wire strands are typically pre-tensioned during the prefabrication process, but may also be post-tensioned in the field.

 

505

Prestressed Concrete

 

-

 

Box Beam, Multiple Adjacent

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes concrete and prestressed wire strands in the manufacture of prefabricated main load carrying members.  The main load carrying members consist of multiple prefabricated box shaped beams placed immediately adjacent to one another.  Traffic loads are applied directly to the top of the box beams or to a wearing surface placed on top of the box beams.  Prestressed wire strands are typically pre-tensioned during the prefabrication process.

 

601

Prestressed Concrete Continuous

 

-

 

Slab

1

Historically Significant and 50 years or more in age

A multi-span span bridge having a superstructure that continues uninterrupted over interior supports and is composed of a cast-in-place concrete slab strengthened through the use of prestressed wire strands.  Prestressed wire strands are typically post-tensioned during the field construction.

 

602

Prestressed Concrete Continuous-

 

Multi Beam

1

Historically Significant and 50 years or more in age

A multi- span bridge having a superstructure which utilizes concrete and prestressed wire strands in the manufacture of prefabricated main load carrying members.  The main load carrying members consist of multiple (three or more) prefabricated beams located below the portion of the superstructure that is in direct contact with traffic loads.  Prestressed wire strands are typically pre-tensioned during the prefabrication process, but may also be post-tensioned in the field.  Cast-in-place concrete and steel reinforcement bars are utilized in the field to create conditions such that the beams continue uninterrupted over the substructure units supporting the middle-portion of the bridge.

 

702

Timber

 

-

 

Multi Beam

1

Historically Significant and 50 years or more in age

A one span bridge or a bridge consisting of a series of simple spans having a superstructure which utilizes timber as the material for main load carrying members.  The main load carrying members consist of multiple (three or more) timber beams located below the portion of the superstructure that is in direct contact with traffic loads.

 

738

Timber

 

-

 

Pony Truss, King Post or Queen Post

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes timber as the material for main load carrying members.  The main load carrying members consist of timber trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic.  (See Truss Type examples.)

 

770

Timber

 

-

 

Truss (Other Unclassified Truss)

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes timber as the material for main load carrying members.  The main load carrying members consist of steel trusses located adjacent to each side of the superstructure.  The trusses are placed above the portion of the superstructure that is in direct contact with traffic.  The arrangement of the individual elements of the trusses do not match any of the commonly used truss types.  (See Truss Type examples.)

 

811

Masonry

 

-

 

Arch Deck, Filled Spandrel

1

Early Examples

 

1880 and Earlier

 

 

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure composed of stone masonry.  The main load carrying member of the superstructure consists of an arched stone masonry slab that bears on and thrust against the lower portion of substructure units located at each span end.  A vertical stone masonry wall is constructed on each side of the arched slab for the entire distance between substructure units. The area above the arched slab and between the vertical walls is filled with earthen material.  A pavement is constructed on top of the fill material to carry traffic.

2

Late Examples

 

1881 and Later

 

950

Iron

 

-

 

Thru Truss, Pratt, Eyebar

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes iron as the material for main load carrying members.  The main load carrying members consist of iron trusses located adjacent to each side of the superstructure.  The trusses extend above the portion of the superstructure that is in direct contact with traffic, and the tops of the trusses are connected to each other by bracing elements.  The lower chord and diagonal elements of the truss are composed of iron eyebars with pin connections at the joints.  (See Truss Type examples.)

 

970

Iron

 

-

 

Truss

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of simple spans, having a superstructure which utilizes iron as the material for main load carrying members.  The main load carry members consist of iron trusses located adjacent to each side of the superstructure.  The trusses are placed above the portion of the superstructure that is in direct contact with traffic.  The arrangement of the individual elements of the trusses do not match any of the commonly used truss types.  (See Truss Type examples.)

 

A07

Precast Concrete, Not Prestressed

 

-

 

Rigid Frame

1

Historically Significant and 50 years or more in age

A one span bridge, or a bridge consisting of a series of non-integral spans, which utilizes concrete with steel or iron reinforcement bars in the manufacture of prefabricated main load carrying members.  The horizontal top element of the prefabricated member is constructed integrally with vertical end elements in a manner that creates a rigid connection at their intersection with one another.

 

B28

Post Tensioned Concrete Segmental

 

-

 

Segmental Box Girder

1

Historically Significant and 50 years or more in age

A multi-span bridge having a superstructure that is uninterrupted over interior supports and composed of concrete strengthened through the use of steel reinforcement bars and prestressed wire strands.  The main load carrying member of the superstructure is box shaped with a hollow interior.  The individual box segments are either prefabricated or field produced using cast-in-place concrete.  The individual segments are held together by prestressed (post-tensioned) wire strands.  The top of the box and cantilevered projections of the box top provide the surface on which traffic loads are applied.

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