Iroquois 1250 Bridge

"TR-247 Bridge"

Most Recent Visit To Bridge: August 13, 2006

Overview of the Bridge

This bridge is easily the most historically significant truss bridge remaining in Iroquois County (keep in mind the CR-9 bridge is an arch), and this bridge can be considered a nationally significant bridge as well because of its rare design, as well as historic integrity. This significance unfortunately is not yet recognized by the government or the public. This bridge consists of three spans, each of a different design. Two of the spans are approach spans. The main span of the bridge has the greatest significance, as a bedstead truss bridge that an exact date is unknown but can be dated to pre-1890. The western approach span is also extremely significant in its own right, as a rare example of a distinctive design of lightweight double-intersection Warren pony truss that was used in the early 20th century, suggesting that it is newer than the bedstead span and thus not part of the original structure. Regardless it is still a significant portion of the bridge. The eastern approach span is a simple steel stringer span and is not comparatively noteworthy. 1904 was the date listed in the inventory for the construction date of this bridge. The bedstead portion of the bridge, bearing the name of the Smith Bridge Company, must be older than that. The Smith Bridge Company became known as the Toledo Bridge Company long before 1904, in 1890. The 1904 date might refer to the "newer" pony truss approach which uses a design seen in this early 20th century period.

About The Bedstead Span

First, an overview of the bedstead truss. The bedstead truss bridge (sometimes called a truss leg bridge) was an economical type of bridge, marketed for its inexpensive design. By using vertical endposts that extended below the bottom chord, the end posts also doubled as supports for the bridge. The result is that a much smaller abutment was needed for the bridge, which significantly reduced costs. This seemed like a good idea, but it turned out to have a major problem. The relatively slender truss supports which often extended into the flood levels of the water, were extremely vulnerable to debris from any floods that occurred. The truss posts could be bent, which greatly weakened the strength of the supports. Michigan's Ball Road Bridge is an example of a bridge that still remains today, yet has some of this sort of damage done to it as seen here. Given, this, the design didn't stay popular as long as other truss bridge types, and worse, the damage done to these bridges by the floods undoubtedly put them up for replacement by their owners much sooner and more often than other truss bridge types. The result is that today this bridge type is extremely rare.

This Iroquois County example is as a result an example of a rare structure type. As a four panel structure it is also a fairly large example of the type, since bedstead truss bridges generally were rather short structures. Consider the three panel size of the Ball Road Bridge and also consider the listings here. Also, this bridge is a rather impressive and visual example of the bedstead design, since the truss supports are very long and visible, and the layout and design of the bedstead is thus clear. In comparison, the single span Ball Road Bridge doesn't look so bedstead-like because its legs are flush against an abutment. The Iroquois County bridge features pinned connections and a wooden deck. There are no railings on the bridge. There may have been no railings ever. On the other hand, the eastern stringer approach span has some simple metal railings, which perhaps were on the bedstead span also at one time.

One thing that is truly amazing about this bridge is the truss supports are not visibly damaged or bent, suggesting that this bridge was one of the few bedstead bridges that actually worked out! Oddly enough, the only place I noted any damage was on the bottom chord where there are some eye bars with minor bending and twisting.

The bedstead span retains builder plaques crediting the Smith Bridge Company of Toledo, Ohio with building the bridge, although the plaques unfortunately are a design that didn't feature a date. I am unsure why a few bridge companies selected undated plaques for some bridges. Anyhow, one nice thing about the Smith Bridge Company from a researching perspective is that it was sold in 1890 and the new owners renamed the company calling it simply the Toledo Bridge Company. Since the plaques show the Smith Bridge Company name, the bridge must pre-date 1890. As my guess, I would suggest a circa 1885 date. One unusual design feature of the bridge is that there is no v-lacing or lattice on the bridge's members and chords. On average, vertical members will have v-lacing or sometimes lattice. On this Iroquois County bridge, the verticals have battens instead. Given this, you can see some similarities between this bridge and Pennsylvania's Dotter Road Bridge also built by the Smith Bridge Company.

About The Pony Truss Approach Span

This pony truss approach span is similar to the Michigan's Powers Highway Bridge. In fact the basic design of the bridges are essentially identical. Both are double-intersection Warren pony trusses with riveted connections and extremely lightweight members and chords. This distinctive design of bridge is very rare, although whenever one shows up, the design is almost identical. This is typical of early 20th century bridge design where the designs became more standardized. Atypical of the early 20th century is the lightweight design of the truss, during a time when weight requirements were on the rise. But in the early 20th century, the lightweight design was likely used as an inexpensive bridge design that would offer enough weight capacity for lightly traveled rural roads. In the case of the Iroquois County bridge, the lightweight design would have fit perfectly with the fragile bedstead span. I assume that this pony truss approach does not share a construction date with the bedstead and that it replaced some other unknown approach span at this location. Given the 1910 date listed for Michigan's Powers Highway bridge, and the 1904 date in the bridge inventory for the Iroquois County bridge, which was obviously incorrect in reference to the bedstead, seems like it might apply to this approach span.

A Bridge Worthy of Preservation

This bridge is not only worthy of being preserved, in my opinion there is no other acceptable course of action. Both the approach span and the bedstead are extremely significant, and together they form a bridge that is undoubtedly unique. Given what I saw in Iroquois County, I believe their historic bridges are only here because they don't have the money to replace them. It is an unfortunate irony that rural areas usually lack both the money and public awareness to preserve historic bridges, yet the oldest and most significant bridges usually are found in rural areas. This is why external federal or state funding needs to be developed that will provide rural areas with the restoration and preservation of their historic bridges. In the meantime, if I hope that any of Iroquois County's money is spent on this bridge it continues to be spent on maintaining the bridge.

Another Similar Bedstead Structure in Iroquois County

This bridge's bedstead span is similar to the Iroquois 2800 Bridge, suggesting that the 2800 bridge might have perhaps been built by the Smith Bridge Company as well, although it does not prove anything. The 2800 bridge has v-lacing on the verticals, so it is a bit different. The 2800 bridge is significant, but not as much as this bridge because its builder is unknown, and also because the legs of the bedstead have been removed.