Metcalf Street Bridge

Information and Findings From Ohio's Historic Bridge Inventory

Setting/Context

The bridge carries 2 lanes of traffic and a sidewalk over 11 tracks of the Norfolk Southern RR yard in Lima.

Physical Description

The bridge has a 308'-long main span that is a heavily skewed, pin-connected, Baltimore thru truss with massive portal bracing. It is traditionally composed of built-up compression members and eye bar tension members. The approach spans are 20'-long T beams. The bridge is supported on concrete bents and abutments.

Integrity

Deck and railing replacement, 1988.

Summary of Significance

The 1923 Baltimore thru truss bridge is a complete long-span example of its type/design. The truss type/design was developed in the 1870s and used through the 1920s. Although a technologically late example, it is 1 of only 3 dating from 1923 to 1930 in the survey, and the only pin-connected example. Other than deck replacement, there has been no significant change in the bridge's status since the prior inventory. The eligible recommendation of the prior inventory remains appropriate.

"The Baltimore truss, specifically, was designed by engineers of the Baltimore and Ohio Railroad in 1871. The truss was adapted for highway use as early as the 1880s, often for spans of modest lengths. When steel replaced wrought iron and rigid, riveted connections replaced pins in the early decades of the twentieth century, the Baltimore truss was used for longer span highway bridges until the 1920s. The Baltimore truss is basically a parallel chord Pratt with sub-divided panels in which each diagonal is braced at its middle with sub-diagonals and vertical sub-struts. The logic leading to subdivided panels stems from the need to maintain an economic spacing of floor beams in longer span bridges. As the distance between chords increases, so does the width of panels. In order to maintain optimum slope of diagonals (45 - 60 degrees) and, an economic spacing of floor beams, the panels were subdivided at intermediate points between the main vertical members. The Baltimore truss is significant for its association with the railroad. Highway bridges built using the Baltimore truss are not amongst the more common bridge types and are considered significant if they retain their character-defining features. Such features include the elements that comprise its form-basically it is Pratt with parallel top and bottom chords, but with generally wide, subdivided panels in which each diagonal is braced at its middle with sub-diagonals and sub-struts. The end posts are inclined. Character defining features include its parallel top and bottom chords, verticals and diagonals (including substruts or sub-ties), floor beams, stringers, struts, form of connection, and portal features (e.g., struts, bracing)." [From: A Context for Common Historic Bridge Types by Parsons Brinckerhoff, October 2005]

Justification

The late example of a pin connected thru truss is one of 13 extant examples of pin connected bridges with polygonal upper chords and/or subdivided panels in the state that date from 1888 until 1923. Moderate significance.

Bridge Considered Historic By Survey: Yes