Abandoned bridge in Ohio
Mill Road Bowstring Bridge, Bladensburg Ohio
This bridge is a rare example of a metal bowstring arch-truss bridge, a type that represents an import, segment of engineering history, that was constructed by a leading bridge company with patented parts by a national iron fabricator.
The bowstring arch-truss was first patented by the famous bridge engineer Squire Whipple in 1841. The Wrought Iron Bridge Company of Canton, fabricators of this bridge, was formed in 1866 by David Hammond, who patented a number of designs in the 1860's and 70's. Job Abbott was the vice-president and chief engineer and Michael Adler was the general superintendent. Under their leadership, the Wrought Iron Bridge Company became one of the leading and widest ranging metal bridge fabrication firms in the nation.
They circulated agents and erected structures throughout the New England, Eastern Midwest, Southern, and Southwestern states. Their Book of Designs of Wrought Iron Bridges published in 1874 included a variety of bowstring arches; deck arches; low trusses; Single, double and triple intersection Pratt through trusses; combination trusses; and girder and swing bridges. They were also among the forerunners in heralding the advantages of wrought iron bridges over wood or cast iron. The same book included a history of iron bridge buildings in Europe and America, and articles on the strength, durability, resistance to corrosiveness; and working loads for wrought iron structures.
The Phoenix Iron Company was a major innovator in the use of iron in engineering structures. In this and earlier structures, the Wrought Iron Bridge Company utilized this company's patented designs for compression members, but soon after, invented their own design so that bridges of the late '70's and 1880's are entirely derived from the Wrought Iron Bridge Company patents. By the turn of the century, the bowstring arch-truss bridge had been supplanted by more durable iron box trusses. High strength steel and reinforced concrete, coupled with greater weight requirements have virtually eliminated this type of bridge in Ohio.
When this bridge was constructed here, an active mill and other structures served to make this site a locally important settlement and trading center. Today, only one farm-house remains in this vicinity along this lightly travelled road. The decline of the settlement and the cessation of the mill operation have enabled this bridge to be among the handful of bowstring arch-truss bridges that survive today in Ohio.
Bridge Description
The Mill Road Bridge is an iron bowstring arch-truss bridge that spans Wakatomika Creek near Bladensburg. It is located on a dirt road in a hilly rural area. The road descends a gradual embankment from the west toward the creek. Trees and brush line the banks of the creek, but fields are located in the flood plain adjacent to the stream. To the north is a woods and to the south is a farmhouse and barns. The village of Bladensburg is about a mile northwest of here.
The bridge is about seventy five feet long, with a clear span of about seventy feet. The overall width of the structure is about nineteen feet with a roadway that is sixteen feet wide. Two arched iron tubes form the main compression members of this bridge. They rise to a height of six feet six inches in the center of the bridge and are braced laterally by a series of small diagonal struts on each side and by the roadway itself, although there are no overhead bracing members. At intervals of about eight feet, vertical members are suspended from these rods to support the roadway. Light tension members serve to tie the bridge together and keep the two massive tubes from spreading outward.
The two compression tubes bear the name of the Phoenix Iron Co., Phila., Pa. at regular intervals along their length and a patent date of June 16, 1862. They are perhaps the most unique elements of this bridge and are composed of four iron plates fastened together to form a single rigid hollow tube.
Wooden planking covers the roadway and is supported by iron beams, which are in turn supported by larger I beams suspended from the two main compression members. The bridge rests on two piers, composed of rock faced sandstone and built up on both ends by earth fill to achieve a height of about fifteen feet above the stream level. A metal plate identifies the builder and has a patent date of April 26, 187(5)? (last digit is missing).
The bridge is now closed to vehicular traffic and is in poor condition. Much of the wood deck is missing or is badly deteriorated. The iron frame has lost its paint and is rusting, although the structure itself appears to be intact and has not been altered by new guardrails or damaged by collisions.
Roadway deck, looking east (1979)
