Benson Street Bridge

The concrete pony arch bridge was designed by E. A. Gast, deputy county surveyor for the county, under the direction of County Surveyor Clinton Cowen, with Hugo Eichler assisting in the design. ^[2] A construction contract was awarded to Peter Praechter for $7,127.

The bridge replaced a through Howe truss with a 73-foot span and a 20-foot clearance below the deck. ^[2] Because of frequent flooding, the new structure could not reduce the width of the waterway opening. A traditional filled concrete arch was rejected for the same reason. Two estimates were submitted: one for an $11,000 steel girder bridge and another for an $8,600 reinforced concrete bridge, the latter was accepted.

Construction took place between 1909 and the fall of 1910. ^[2] The bridge was the first of its type in Ohio, and one of the earliest in the United States, and was nicknamed the “rainbow arch” for its distinctive appearance. ^[1][2] It also predated James Barney Marsh’s 1911 patent for a similar design. ^[2]

Gast’s design differed from Marsh’s in that it featured hingeless arches, with no plates inserted along the arch and no provisions for movement at the abutments. ^[2] Heavy transverse beams beneath the ends of the arches were laid directly on the abutments, and the arch ribs were designed to accommodate all temperature stresses. In contrast, Marsh’s design incorporated slidable wear plates at points of contact between the bridge floor, beams, and abutments to allow for expansion and contraction.

An identical bridge was built in 1911 across the West Fork of Mill Creek, but was removed in July 1983. ^[2]

The structure was rehabilitated in 1992 by the Fred A. Nemann Company under the direction of County Engineer William W. Brayshaw, Bridge Engineer Stephen J. Mary, and Restoration Engineer KZF Inc. ^[1]