A Bowstring Arch Bridge that is not historic?
Before starting in on this subject, here’s a rhetorical question for all pontists and highway engineers who have pre-1950 bridges in their database: Why are historic bridges demolished and replaced? Is it because of structural issues? Is the cost for maintenance too high? What about liability and safety concerns? And lastly, have you ever been in a situation where you have a historic bridge and you were forced to choose between tearing it down and replacing it or rehabilitating (or restoring) it to prolong its useful life?
Author’s note: Discussions and stories are welcomed both here as well as via facebook and LinkedIn.
There are many reasons for demolishing a historic bridge, but just as many reasons countering it in favor of rehabilitation and restoration, either for further use as a vehicular bridge or reuse as a recreational bridge. However, one bridge in Otoe County, Nebraska is being replaced as part of the plan to reconstruct and expand the bike trail network, because it is not considered historic. Logically speaking, if a historic bridge has little or no value in terms of aesthetic appearance and historical significance, or if it was altered to a point where its value has been compromised, it would be understandable. What is driving historians, preservationists and pontists to the point of insanity is the fact that this bridge is a bowstring arch bridge, a truss type that is becoming rarer to find nowadays.
A bowstring arch bridge, in simple terms is a type of truss bridge where the top chord creates an arch span that is supported by vertical and diagonal beams. It is similar to the Parker Truss design except the fact that the top chord is curved and not polygonal like its cousin. Squire Whipple designed and patented the design in 1848 and various bridge builders have varied their design based on the design of the top chord. The most common are those with the Phoenix columns (patented by the Wrought Iron Bridge Company) and the H-beam design with bolts sticking out on the top side, which was patented by the King Bridge Company. The longest bowstring arch bridge in the US is the 190-foot long Kern Bridge near Mankato in Minnesota, built in 1873 over the Le Seuer River and closed since 1990. The longest in the world is the Blackfriar’s Bridge over the London River in London, Ontario in southern Canada. The 1878 bridge has a span of 224 feet long. Both of these bridges are works of the Wrought Iron Bridge Company.
The Steinhart Park Bowstring Arch bridge, located at the park bearing its name west of Nebraska City is an example of a bowstring arch bridge with H-framed upper chords, but one that is rare in itself in Nebraska. It is unknown where the bridge was originally built, but records indicated that it was relocated to the park to span South Fork Table Creek several years ago. The only modifications done on the bridge was halving the width and replacing some bolts, but it remained in service until its closure because of safety concerns. Plans were in the making to construct a bike trail that would encircle the western portion of the city and use the park as its hub point, as stated in a recent article by the Hamburg Reporter in Hamburg, Iowa. This would include using the location of the bowstring arch bridge as a crossing. While the city received a grant for the bike trail network, construction was delayed due to the historic significance of the bridge, hence involving the state historical preservation office to determine how historically significant the bridge really is.
The decision made by Jill Dolberg that the bowstring arch bridge is not considered historic despite its rarity cleared the last hurdle for the demolition of the structure to commence, but it has sparked an outcry from the bridge and preservation community regarding the treatment of historic bridges by the local government and private sectors. It also contradicts the way historic bridges are being treated despite being modified for reuse. One has to look across the Missouri River into neighboring Iowa to see enough examples of historic bridges being reused, some of which still maintain their status on the National Register of Historic Places. Two examples come to mind: the Yellow Smoke State Park Bridge in Dennison (Crawford County ) and the Moneek Bridge in Castalia (Winneshiek County). The one in Crawford County was constructed in 1945, one of a dozen bowstring arch bridges built at that time to replace the ones that were destroyed in the flooding. The one at Castalia was built by Allen and McEvoy, local contractors , in 1872. Both were relocated to parks when they were rendered useless for vehicular traffic, and despite modifications, both were considered historically significant as they still are listed on the National Register of Historic Places.
To consider the bowstring arch bridge as non-historic serves as a slap in the face and leads to the question of whether the preservation policies that exist on the state and national levels are sufficient enough, or if tougher measures are needed to ensure that more funding and technical know-how as well as tougher sanctions against owners for neglecting historic properties are needed to ensure that all parties are better informed about the possibilities for restoring historic bridges and making them safer for people to use, while at the same time educate them on how to maintain historic places of interest, rather than neglect them like it was the case with this bridge.
As plans are underway to raze the bowstring arch bridge, making way for a modern and rather bland structure to take its place to serve the planned bike trail, many people will most likely pay homage to the bowstring arch bridge, while at the same time, protest this decision to let go of one of the rarities of Nebraska City. Already the city has lost two key Missouri River crossings to progress (a highway bridge and a railroad bridge built by George S. Morison), and the loss of this bridge will contribute to the city becoming more modern, at the expense of history. The decision to not consider the bowstring arch historic enough- and thus allowing the demolition to proceed- is being scrutinized by many as being one of the most illogical decisions made by a historian or any member working for a state historic preservation office in the country. It is definitely not winning any points with the author of the Chronicles, who might have an award ready for Nebraska City and the Nebraska SHPO to accept…..
Author’s note: Special thanks to James McCray for allowing the author to use of his photos for this article.
REMINDER: Do not forget! Nominations for the 2012 Ammann Awards are still being taken. Deadline for accepting photos, historic bridges and historic bridge preservationist is 1 December. At the moment we have a few entries, but if you submit your entries, the numbers will increase and we will have a wide selection to choose from regarding voting. Act now and make yourself and your entry known! More info can be found here.