Mystery Bridge Nr. 26: Unusual Truss Bridge in Iowa

Portal and overhead view. Photos taken by John Marvig

Have you come across an unusual bridge while travelling or bridgehunting? If so, what did the bridge look like, and did you do some research to determine what bridge type it was? Many engineers came up with rather unusual bridge designs during the age of industrialization between 1850 and 1920 which were experimented on roads and railroads. While most of them were used rarely and have long since been extinct, like the Kellogg truss bridge which was used on the Philips Mill Bridge in Floyd County, Iowa, there are some unusual bridge types that were used and whose examples still exist today, like this bridge.

The Muchakinock Creek Bridge, located in Mahaska County, Iowa between Oskaloosa and Eddyville, carries the Union Pacific line on a single track and is one of a handful of through truss bridges whose design is rather unique for a short-span crossing. Built in 1901 by the Phoenix Iron Works Company of Phoenixville, Pennsylvania, the bridge features a V-shaped truss design that is subdivided diagonally and for the center panels, horizontally. It is classified as a Warren through truss, though when looking at it closely, it could be perceived as a Pratt through truss with subdivided connections. Even weirder is the upper chord of the through truss span, where instead of featuring sway bracings resembling a Howe truss design, it features bracings resembling the subdivided kingpost truss bridge, similar to the one located at Schonemann Park south of Luverne, Minnesota.  A diagram produced by John Marvig shows the unusual configuration:










Two of the four known bridges that are built using this unusual truss configuration are located along this line. The other two are located over Miller Creek in Monroe County along an abandoned railroad. It is obvious that this truss type was used for short crossings as each bridge averaged four panels and 110 feet in length. But it is unknown not only how many were built between 1890 and 1920 and how many more exist beyond the ones found in Iowa so far.

Example of a bridge of a similar design that existed near Manly in Worth County, Iowa. Photo courtesy of John Marvig

The fabricator, Phoenix Iron Works was famous for its unusual bridge designs, as it constructed the longest viaduct in the world using another unusual truss type, the Fink truss, over Lyon Brook in Chenango County, New York, in 1869. The 830 foot long bridge survived only 25 years and was known infamously for deaths and other haunted stories that occurred there. It was also famous for truss bridges built using the Phoenix column, end posts were built using octagonal sides, as shown in this picture. This contributed to the company producing a spin-off in the Phoenix Bridge Company, which existed from 1883 until 1962 and was responsible for building many key bridges, including the Manhattan Bridge in New York City and the Walnut Street Bridge in Harrisburg, Pennsylvania. The Iron Works has ceased production in Phoenixville since 1984 but the facilities are being transformed into other uses including designating some as historic sites.

For many reasons, the Chronicles needs your help. If you know of any bridges that feature similar designs like the ones found in Iowa as well as the dates of construction, etc., please send a line and provide the information. These unusual bridge types are important parts of the history of America’s infrastructure and many of them have a chance to become a historical landmark, as well as a key component to bike trails that will be developed over the next few years, including the crossings along Miller Creek in Monroe County.  Send your info and comments to or drop them off in the Comment section as well as on facebook. History is important and many of these artefacts deserved to be recognized for their unusual designs and the builders who developed them in the first place. That is what the Chronicles is there- research, preserve and teach to future generations about bridges and their role in architectural and transportation history.

World Heritage Site for historic bridges

Rendsburg High Bridge in Rendsburg, Germany Photo taken by the author in April 2011

Historic Bridges and national recognition. Pending on which country your bridge is located in, bridges like this one in Germany, the Rendsburg High Bridge over the Baltic-North Sea Canal between Hamburg and Flensburg, are protected by federal preservation laws based on their structural integrity, cultural heritage, history in terms of engineering, technology, the connection to certain events, and other unique values. These laws protect the structures from any form of alteration which could potentially compromise the integrity of the structure. At the same time, bridges protected by preservation laws are eligible for grants to preserve them for future generations. This also includes relocating them if they are in the way of progress. Every country has its set of preservation laws covering places of interest on all levels. The Denkmalschutz Law in Germany, conceived by Hartwig Beseler in 1959 covers historic places on three levels (local, state and federal) and lists all artefacts in the heritage books based on significance in terms of the historical, cultural, technical and environmental context. The Rendsburg Bridge was nominated based on technical aspects.  In the United States, we have the National Register of Historic Places, which was created as part of the Historic Preservation Act in 1966 thanks to recommendations by then First Lady Claudia Alta “Lady Bird” Johnson. As many as 30,000 historic bridges are listed on the Register with triple the amount eligible based on four different criteria.

Yet a bridge being considered a World Heritage Site is the most exclusive of all rights given to a structure. Developed by the United Nations Educational, Scientific and Cultural Organization (UNESCO)in 1972, the World Heritage program is designated to areas around the world that are rich in its own heritage, whether it is cultural, environmental, technical or other aspects, and are one of a kind. UNESCO outlined the definition of a Cultural and National Heritage Site in its 1972 Convention which can be seen here.  There are two advantages of having a place be considered a historic site. First it can promote tourism in the area and through its international recognition provide municipalities with additional revenue to maintain the facility and protect it from encroachment by developers. And secondly, areas that are threatened receive funding through UNESCO’s World Heritage Fund, which is donated annually by the public and private sectors and dispersed to areas that need the assistance to find ways to protect the area. Like the National Register of Historic Places in the US, the World Heritage status of a site is put on the red list and removed should it be altered by any form of development that could harm the site permanently. This happened to the Elbe River Valley southeast of Dresden (Germany) in 2009, when the Waldschlösschen Bridge was built directly in the site, thus losing its World Heritage Status. This was the second time in its history that it happened, and the region is the only one in Europe that has been de-listed.

But the World Heritage site also applies to historic bridges as well, for as they were developed, engineers invented new bridge types and other mechanisms that made their construction easier and the structure itself sturdier and safer, while at the same time, keeping their aesthetics by making them fancier for tourists not to miss them when they cross them. Eric DeLony of the Historic American Engineer’s Record in a manuscript produced in 1996 for the The International Committee For The Conservation Of The Industrial Heritage (TICCIH) stated that historic bridges must also meet the requirements that have a universal, one of a kind value:

A World Heritage bridge, like other properties, must meet the test of authenticity in design, materials, workmanship, or setting (the Committee has stressed that reconstruction is only acceptable if carried out on the basis of complete and detailed documentation of the original artefact and to no extent on conjecture).

But because of their age and rarity, these structures, listed on the World Heritage, also require protection by the laws to ensure that their status is not threatened and that they can remain in its original form without being altered beyond recognition, as DeLony stated in his address to TICCIH:

Bridges nominated for World Heritage listing also must have legal protection and management mechanisms to ensure their conservation. The existence of protective legislation at the national, provincial, or municipal level is therefore essential and must be clearly stated in the nomination. Guidelines for nominations state that each property should be compared with properties of the same type dating from the same period, both within and outside the nominating State Party’s borders.

Unlike the tens of thousands of bridges that are listed as heritage sites on a national level, the number of historic bridges listed as World Heritage bridges are very few in number, with thousands of them waiting in line to receive their international status. This leads to the Bridgehunter’s Chronicles’ Questions for the Forum:

1. Which bridges are listed on the World Heritage Site? Name them, the bridge type and their location.

2. Which bridge was just recently listed on the World Heritage Site? Why was this bridge so important enough to receive this recognition?

3. There is one bridge that is nominated for a World Heritage Site status for 2015. Name that bridge and decide if the bridge should receive such a status with your reasons for your argument.

4. Of the tens of thousands of bridges waiting to become a World Heritage Bridge, which bridges in your country should be listed and why?

The author will provide the answers and his own list of bridges that should be included on Thursday. In the meantime, you are free to post your arguments in the comment section in the Chronicles page here, as well as on facebook and LinkedIn and through James Baughn’s Bridgehunter website.  Happy Bridgehunting and research and loooking forward to your answers and statements.

A bridge type making a comeback: the Melan arch bridge

Photo taken in August 2009

Now the answer to the pop quiz:

In 1894, an Austrian-Bohemian engineer, Frederick von Emperger, decided to experiment with a bridge design over a small stream northeast of Rock Rapids, Iowa. This design was first introduced by his professor, Josef Melan, while studying at the German Technical College in Prague, and featured an elliptical arch bridge that was supported by metal roads running underneath and covered with concrete. At the time of its construction, iron was used for the Melan bridges that were built in present-day Germany, Spain, Czech Republic, Switzerland and Austria. Yet this bridge was the first one to use steel rods, separated by three feet. When Paul Kingsley finished the construction of the bridge in 1894, nobody realized that this was the very first bridge to implement the Melan arch design. Melan and von Emperger continued to build bridges using the Melan design, which included the construction of the Ludwigsbruecke in Munich in 1930 by Melan, and Abteilbruecke in Berlin by von Emperger.  Von Emperger also built bridges in the eastern half of the US before emigrating back to Europe for good in 1898.

The construction of the first Melan arch bridge set the precedent for many more to be built between 1900 and 1940, with the most common ones being found in Iowa and places in the southern and eastern parts of the US.  This includes the Evansdale and McFarlane Bridges in Black Hawk County, Iowa (both destroyed by the 2008 floods and have been replaced), The Como Park Bridge in Minneapolis, Minnesota, the Eden Park Bridge in Cincinnati, Ohio, and five Warren County, Mississippi bridges located at Vicksburg National Military Park.  Yet the bridges fell out of favor for longer beam bridges made of wood or concrete, providing width for cars and length for waterways to flow underneath. Many of these were eventually replaced by concrete or steel culverts, which provided no railings for automobile drivers, but more problems with erosion when flooding and damming by debris persists.

Photo of one of the modern examples of a Melan arch bridge at Sandbar Slough in Iowa. Taken in September 2009

Yet recently, the Melan bridges are making a comeback, as many of them have been populating the roadways for the last couple decades. including three that were built in Springfield, Missouri in 2010 to accommodate bike traffic and a couple built in the Iowa Great Lakes Region- one on Lake Shore Drive in Wahpeton, built in 2008, and another built over Sandbar Slough north of Orleans in 2001, the third crossing and the second one to bypass the first one built in 1915 and still in use. It is unknown where else these bridges can be found, but it is a safe bet that the Melan Bridge is being used as a compromise between cost-effectiveness and environmental protection. Cost- effective because of its short spans but environmental protection meaning that water can still flow freely underneath the bridge and there is no worrying regarding erosion because of high water.

As for the first Melan arch bridge, it was relocated to its present spot at Emma Sater Park in 1964 when a new bridge was to be built in its place and preservationists discovered the historic significance of the structure. 10 years later, the bridge was one of the first historic places to be listed on the National Register of Historic Places. The bridge can be seen today when entering the town from Iowa Highway 9, and a picnic area is available for those wanting to spend time at the bridge. It is a must-see for those who want to know how the engineers’ creativity resulted in another bridge design that was absent for a period of time but is now becoming another norm for use on the highways today, thanks to Josef Melan who invented the arch bridge and Frederick von Emperger who set the tone for today’s engineers to follow.

Name that bridge type: A bridge type making a comeback

Photo taken in August 2009

While truss bridges are making their comeback in a modern form to serve as either a pedestrian or vehicular crossing, this bridge type is rumored to be coming back as well. This is the subject of the Bridgehunter’s Chronicles’ Pop Quiz.

This bridge was the first of its kind to be built in the United States and one of the first to be listed on the National Register of Historic Places. The bridge design was conceived by an Austrian engineer but this bridge was built by a German engineer. Even though the bridge type became popular during the first four decades after this bridge was built in the 1890s, it fell out of favor for concrete beam bridges for the next 60 years. Yet this has started coming back into popularity as the second most commonly used short-span crossing, behind the culverts. Reason: culverts cause back-ups, flooding and erosion. This type can allow water to flow freely under the roadway, alleviating the headaches of farmers and eventually the local politicians who have to take the heat from these particular farmers for making the illogical, cheap decision to install them over normal bridges to begin with.  The bridge in the picture was relocated to a park in the 1960s and serves as one of the masterpieces of a local rural community in the Midwest.

Now it’s your turn! Name:

1. The bridge type and who designed it,

2. This bridge in the picture, who built it and where it’s located, and

3. Another example of a bridge type that’s in existence, both past and present.

The answer will be revealed next week on Tuesday. Until then you can plaster the article or facebook webpages with your answers. Good luck! 🙂

Newsflyer 8 July, 2013






Kansas historic bridge estranged by county officials, Fitch receives new bridge, Viaduct in Indiana demolished, Vertical Bridge on US 1 to come down soon

There is a small informal trend that was started on the website a couple years ago, where a historic bridge that was replaced or torn down would receive the Little Brown Barf Bag because of the senseless excuses for tearing them down to begin with. It is unknown how often the LBBB has been used this year (or who has used them), and most importantly whether the supplier has any left in stock, but the regular customers may have to find an alternative if there’s none left, especially as we have some bridges in this Newsflyer that are target for the wrecking ball. One of them has a new bridge in place, and while bridge fans have been finding the next available restrooms, others are shaking their heads and asking “Why this bridge? It’s really ugly!”  Here are the bridges making the Newsflyer:

Stranger Creek Bridge demolished despite its pristine condition.

Located southeast of Tonganoxie in Leavenworth County, this elegant Pratt through truss bridge with M-frame portal bracings is one of the tallest bridges in the county and one that can be seen along the Kansas Turnpike (I-70). That will no longer be the case by the middle of this week, as crews are working to demolish the bridge as it is rendered useless because of another crossing on Metro Avenue, located north of the bridge. No replacement is being planned for this structure. The bridge was closed to traffic in April even though when looking at the photos here, the structure seems to be in great condition. Why Leavenworth County spent $150,000 to remove this bridge is beyond the logic of many who think that money would best be spent for other projects or at least converting this bridge into a recreational area with the county conservation board owning it. However, given the plan by the county to replace as many as 20 bridges in the next few years, this estranged behavior towards historic bridges makes sense. Word of advice to those travelling through the county, take a half day to visit the remaining bridges, including those along Stranger Creek where this bridge used to be located, for they will be gone soon.

Fitch receives new bridge, much to the dismay of many

“You guys can have your bridge!” as many have said about this bridge near Lowell, Massachusetts. As reported a few months ago, Fitch’s Bridge was removed after being abandoned for over 40 years, leaving the bridge to decay with nature. Without looking at options for rehabilitating the bridge, the city and park district opted to remove and dismantle the bridge with the usage of cranes and welders and replace it with a half-pony/half deck truss bridge that is of Pratt design. Have a look at the photos here and judge it for yourself. The choice is questionable to many who believe a replica of the 1899 bridge would have been the more logical choice, but if the majority favor a mail-order welded truss bridge, then what can a man do but shake his head and ask why…

Viaduct in Indiana removed

Located north of Owasco over Wildcat Creek in Caroll County, the Owasco Viaduct, built in 1893 and served the Chicago-Indianapolis line until its abandonment in 1992, was one of the longest bridges in the state as well as along the line, with a total span of 1278 feet. Yet flooding in 2004 caused one of the piers to shift more than 10 feet over, making the deck plate girder trestle look like the letter ‘S’ instead of being a straight-line bridge. Many people were fearing that the viaduct would not last long afterwards. It stood for nine years until more recently when the demolition crew finally took the bridge down for safety purposes. Says Tony Dillion, who is one of the experts on Indiana’s historic bridges, “Surprised it stood as long as it did.” More on this bridge can be found here.

Three Maine Bridges to be replaced or removed.

This state used to have a large number of historic bridges, just as many as New Hampshire and Vermont, Maine that is. Now the state has joined the race with its western neighbor and Pennsylvania to see how many historic bridges can be demolished to cut costs, for two of its bridges will be replaced and another one, a double decker bridge will have its bottom deck removed. With the Waldo-Hancock and Memorial Bridges gone, the state is on track to being the state with the worst track record regarding historic bridge preservation, with the exception of New Hampshire. Here are the bridges highlighted below:

Sarah Mildred Long Bridge:

Located over the Piscataqua River on US Hwy. 1 in Portsmouth, the vertical lift bridge was one of two located in the region before the Memorial Bridge was torn down, yet it featured a deck truss with a highway span on top and the railroad span at the bottom of the truss. Yet, despite being built in 1940, both Maine and New Hampshire are competing for a grant to proceed with the demolition and replacement of this unique truss bridge. How unique is it? Its lower deck can be slid inwards to allow ships to pass through in addition to the 227 foot long vertical lift span (the bridge has a total length of 2800 feet). Yet as this bridge is eligible for the National Register of Historic Places, even if the two states obtain the TIGER Grant, construction would have to wait until the environmental and cultural impact surveys are carried out. A long battle is in the making to save this bridge under the war cry “Remember the Memorial!” More information can be found here.

Cassidy Point Bridge to become a railroad grade

While this bridge is 43 feet long and carries Danforth Street in Portland, it spans a railroad and owners of the line want the bridge removed. Not to worry. MaineDOT can help you, but it will come at the dismay of car drivers who will have to wait for long 3-mile long trains carrying double-decker coaches and wagons for many minutes. That is the general plan at the moment as the railroad plans to increase traffic on its line through Portland and the bridge to them is a burden to their plan. It is unknown when the project will start but word has it that it will begin soon. More information here.

Androscoggin River Railroad Bridge in Brunswick

Spanning the Androscoggin River in Brunswick, this two-span Baltimore through truss bridge, built in 1909, carrys rail traffic through the city on the top deck, but local traffic on the bottom deck, which is supported by a set of Warren trusses with pin-connections. Going by the name Free Black Bridge, the Pennsylvania Bridge Company structure made the news as Maine DOT, in cooperation with the bridge’s owner, Maine Central Railroad, plans to remove the road deck while leaving the rail truss in use. It is not surprising of the action, for despite the road deck seeing 6-7 cars a day, MaineDOT does not want to have another liability in their hands, which justifies this action.

Free Black Bridge in Brunswick, Maine. Photo taken by HABS-HAER

Registration for Historic Bridge Weekend due 15 July

For those wanting to register for the evening dinners and Kate Shelley tour portions of the 2013 Historic Bridge Weekend in eastern Iowa, you have another week until registration comes to a close. You can register for the HB Weekend via facebook or contact Jason Smith at the Chronicles as You can also contact him if you want to join the bridgehunting tour only or if you have any questions pertaining to the HB Weekend between now and 31st July.




Motor Mill Bridge near Elkader, Iowa Part 2

Motor Mill Bridge in its original form. Photo provided by Hank Zaletel.









Part 2 of the series on Motor Mill Bridge near Elkader, Iowa is a long story about how the bridge, which was washed away by floods twice in 1991 and 2008, received new life as a replica that is now open to traffic. This time, it’s from the point of view of Jon deNeui, who is Vice President of the Motor Mill Foundation.  Here is the story behind the bridge:

Bridge restoration. Actually a replacement. I became involved with Motor in 2004 and as the Motor Mill interest group discussed how the planning should go I developed the idea that the repairs and restorations being discussed would cost in the 1 to 1.5 million dollars. The visitor rate on the open house weekends sounded like a variable 20 people. It seemed to me that the major factor limiting visitors was the approx. 8 miles of dusty gravel road. I guessed that that would filter a lot of visitors out. If that was a significant factor, how could we get more visitors to come. The county supervisors had indicated that major county spending at Motor was not going to happen so seal coating Grape and Galaxy roads was out of the question. I suspect that if we could increase the visitor vehicle numbers that the county would respond and upgrade the roads. Since the road across the river only counted 1.5 miles of gravel it became clear that developing access from that direction would be most effective. For this to work, crossing the river would be the key problem. Several options were discussed. These included modern bridges at the same or other locations as well as pedestrian bridges. The county would not consider any bridge construction investment leaving this up to the Motor Mill Foundation. With one span of the steel, pin connected Pratt through truss remaining I had the chance to get to know the structure and it’s design. Since the cost of a new bridge would be the responsibility of the Foundation I started looking at the least expensive way to get a bridge. Since there was no county owned land for parking on the other side of the river it became clear that the bridge would have to be “vehicle capable”. The County offered that if the bridge was “vehicle capable” they would include the bridge in the county secondary road system. This solved a major set of problems involving maintenance and operating costs. As I got to know the old bridge structure I began to see that building the same dimension bridge on the original masonry foundations was important. Then I could see that the 1899 span was made to be assembled in a low tech process that I thought could be in large part handled by volunteers. I found local masonry contractors and bridge erectors who would be willing to share the basic work with volunteers. We had a local steel fabricator who could cut the parts needed. Local truckers would help with material transportation. I knew that the heavy workl would need to be done by experienced professionals, no problem there. At that point I was scheming on how I could get a steel supplier to partner on the steel materials.

The problem would be to convince my friends that the kind of bridge and location of it could only be reached by one path. by 2006 I had a lot of answers and had put some estimated costs built from actual proposals from suppliers, fabricators and contractors. In 2007 and early 2008 the Motor Mill Foundation board came to agree with the proposal to construct a replica of the old steel truss bridge with a new one. The county and state historical folks agreed to the new replica with a proviso that the remaining span would be kept as an exhibit. As time passed the costs went up and finding a cooperative engineer was a problem.
In June of 2008 the flooding Turkey River took out the remaining span. This set up a series of events that led to a new “old” bridge. FEMA arrived in the late fall asking why this “Historical Site” hadn’t asked for flood repair dollars. I had thought that the flood damage was minimal to our buldings and since the remaining span of the bridge was borderline junk before the flood, there was little to ask for. It became clear that FEMA was interested in our historical site and actually was interested in replacing the single span lost in 2008. Once the agency’s willingness to support the replacement of half a bridge was confirmed, Tim Englehart obtained a REAP grant and the project was nearly funded. It seems that the years of discussions and exploring a new bridge and with all involved persons agreeing on what should be done, made our bridge nearly a shovel ready project. That didn’t hurt us either.

General History: Motor Mill was a dream project that developer/mill builder John Thompson wanted to build. He bought the property nearly twenty years before the Motor Mill was built. Both the Mill Complex and the bridge were begun in 1867 and 1868. The first bridge structure was a three span wood truss bridge. Part of the limestone for the bridge abutments and piers was quarried from the hole needed for the basement of the mill. The lime kiln built to produce lime for the Mill buildings also provided lime for the bridge masonry. Sand for the whole project was taken from the riverbed. The mill was finished late in 1869 with a test run between Christmas and New Years. The mill went into full production in January 1870. Wheat was purchased locally and hauled to the mill in wagons. A narrow gauge railway was attempted but after being washed out was abandoned. The mill continued to produce flour from local and imported wheat until it was closed in about 1885. Thompson and partner Crosby bought the third partner’s share and then petitioned the court to dissolve the remaining partnership. Lack of adequate transportation of wheat coming in and flour being shipped out was one serious factor limiting the success of the mill. Another factor was repeated population explosions of Cinch Bugs. These bugs decimated the local wheat growing and the farmers had to find a crop that could generate cash flow for their needs. The mill was sold to local farmers and was used for private farm related purposes. In 1905 the Klink family bought the mill and related property. They continued to own this property until 1983 when Clayton County bought the historic site for future use as a historical site.

Reconstruction: In 2004 and 2005 I became fixated on the old bridge span and spent a lot of time looking and figuring out the structure. I made Auto Cad drawings representing the existing structure. These drawings can be seen if you want. The first thing I discovered was that the spans had been prefabricated to be assembled in the field. All the fabrication shop assemblies were hot riveted together. All the Field connections were bolted. The primary erection was a combination of 2? pins and 1/2? and 5/8? bolts. This was when I began to think that the spans were relatively simple and the parts could be made and assembled locally by volunteers and cooperating businesses. The final erection would be done by a bridge contractor. After the real money became available the idea of volunteers doing the work was replaced by a professional team of engineers and contractors. When this changeover happened the concept of a nearly complete replica of the original steel spans was a major factor agreed to by nearly all involved. The Bridge components were fabricated near ST Paul MN. The bridge was erected by Minowa Bridge Construction from Harmony MN. The steel was delivered in late Sept. 2012. Masons began working on the foundations in early October 2012. Assemblly of the spans began later in October and by the middle of November the spans were set into place. The work was finished and a ribbon cutting opened the bridge to traffic on December 8, 2012.

Historic status: The project had been discussed with the Iowa State Historical people in Des Moines from the early days in 2004. Clayton County Historical Preservation, County Supervisors and the National Park people were contacted and many discussions brought together the concerns both concurrent and conflicting. The Historic Register accepted the proposed bridge replacement with the afore mentioned proviso that the remaining span be converted to an exhibit that people could come and put their hands on. The proviso was dropped when the poor old span was destroyed. However they had seen my cad drawings of the old bridge enough times that we were in good position to assure them what we would be putting back. We never lost the historical site status.

Funding began with a FEMA grant followed by a REAP grant and supported by several smaller grants and gifts. We have set out to obtain enough funds to cover some costs which couldn’t be coverd by the grants and gifts.

The new bridge is not a full replica of the old spans. The engineers had some serious reluctance to repeat the Pinned Connections. The peculiarity of the pin connected Pratt truss was anchored in an engineering concept called “Critical Fractre”. This means that within the structure of the span if any part fails the whole thing falls down. Since the bridge advocates were firmly based in the need of a visual replica of the old bridge the engineers were convinced to use an overall replication of the old bridge with modern connection systems and additional strength where potential fractures could happen. They also substituted welded joins for riveted connections. We/I didn’t get everything we wanted and the engineers didn’t get everything they wanted. But we agreed that the structure would be a good strong one. One benefit of our situation was that the IaDOT had no jurisdiction and was consulted for several standards such as guard rails etc. IaDOT review and oversight was not something that slowed our progress. For most visitors the bridge looks just like the old one. I’m working on getting accustomed to the variations from the original. The bridge is a good strong and serviceable structure.

Public Response to the bridge replica/ project: In the early stages the public response was, “I’ll believe it when I see it.” In the mid stages their response was, “It’ll never get off the ground.” When the funding was obtained and we moved into the building stage the comments were, more like, “You can’t get it done for that little cost.” Actually their response was hopeful and wistful about their memories of the old bridge. As we moved into the later stages more and more of the general public as well as public figures became more supportive and encouraging. They just had to get past their doubt. Now the public has visited and is happy with the results. They can’t believe that the 72,000 pound design strength was accomplished for the low cost. But folks are talking to all of us about how great the finished bridge is for the county.

To see the interview with Tim Engelhardt, please click on the link here.

The replica version of Motor Mill Bridge. Can you see the differences between the one photographed by J.R. Manning and the original provided by Hank Zaletel?

Motor Mill Bridge near Elkader, Iowa Part 1

Motor Mill Bridge in its original form. Photo provided by Hank Zaletel.









There was a round of critics who claimed that truss bridges are obsolete and cannot be used for today’s highway standards, especially because they are fracture citical, meaning if one part fails, the rest of the bridge fails. This echo was first started in response to the Minneapolis Bridge Disaster of 2007 and reinforced because of the collapse of the I-5 Skagit River Crossing. If that was really the case, then there are two questions that the critics should try and answer:

1. Why are truss bridges still being built today to serve vehicular traffic and

2. Why are bridges like this one presented here, being replicated?

The Motor Mill Bridge, located over the Turkey River on Galaxy Road southeast of Elkader in Clayton County, Iowa maybe considered one of the finest examples of how truss bridges like this can be built, let alone how bridges lost to a disaster can be replicated to almost the finest details.  The two-span pin-connected Pratt through truss bridge was built in 1899 by a local contractor, A.C. Boyle, whose bridge company was located in MacGregor (along the Mississippi River south of Prarie du Chien) and who was responsible for constructing many small crossings in northeastern Iowa at the turn of the century. This bridge, which features a 7-rhombus Howe Lattice portal bracing with heel bracing served traffic for 93 years before the floodwaters knocked out the southern span in 1991. While the northern span survived the 1993 flood, it finally fell to nature’s rath in 2008. This was when the people of Motor Mill took action, and four years’ of tireless efforts paid off with a replica built late last year, which is now open to traffic.  I had an opportunity to interview the people at the Mill about trials and tribulations behind rebuilding the bridge and had two people provide some details of this massive artwork that was reconstructed, literally from scratch. This article will feature a Q&A session with Tim Engelhardt while the next one will feature a summary provided by the Motor Mill Foundation:

1.What factors motivated you to embark on the bridge restoration project?


The motivation was the south span of the two span bridge was washed out in 1991.  Since that time, the Clayton County Conservation Board pursued a variety of means to replace the span.  The public seemed to want the bridge replaced, the county road system was fine with not replacing it but the Conservation Board felt the bridge was important to the Motor Mill Site for access.  We kept running into the historical nature of the structure to prevent the replacement of the south span.  At one point, we were told the only way it could happen if we built a pedestrian bridge within the remaining span.  At an estimated cost of $1 million dollars, there was no way the residents of Clayton County would like spending that much money for a bridge they could not drive across.

After the flood of 2008, which washed out the remaining north span the situation changed.  The bridge replacement then became a FEMA project with the “right” historical person involved.  Through a variety of conversations, proven planning, completion of several other projects at the site and several people helping we were able to get the project approved to replace the north half of the structure.  We had preserve the stone work on the north and south abutments and the center pier.  No longer did we need to preserve the bridge structure itself. 
 Supplemental question: Why restore a bridge whose one span was destroyed in 1991 and the other in 2008?

The public seemed to have wanted the bridge replaced.  Access to the site was 7 miles of gravel road of which the last couple of miles was a dead end.  We had developed the Motor Mill Foundation, which had done a lot of work at the site with replacing roofs, flooring and having the mill open for tours on weekends.  The bridge access would allow only 2 miles of gravel and better security.


2. What is the general history behind the mill and bridge?

 Instead of writing this out, there is a section about the bridge on the motor mill website you may read here:


3. Who did the construction of the bridge?

 VJ Engineering designed the bridge and Minnowa Construction, Harmony MN did the actual construction of the bridge.


4. How did the construction of the bridge replica influence its National Register of Historic Places listing (bridge was listed until 2008)? Did you receive this status back?

The status on the bridge structure itself was dropped as soon as the north span went underwater.  The stone work is still listed along with the rest of the site.  The new bridge is not part of the National Register of Historic Places.  As part of a mitigation project for another FEMA project at Motor Mill, the site is being expanded on the current listing.


5. How did you gather enough funding for this project? Who was all involved?

 FEMA funded part of it, we received a REAP Grant through the state of Iowa, received funding from the Iowa Great Places Grant, and a local grant through the Upper Mississippi Gaming Corporation and private donations.  90% of the funding was through grants.

Author’s note: REAP stands for Resource Enhancement and Protection and information on this can be found here.


6. Looking at the Sutliff Bridge (whose easternmost span was washed away by floods in 2008), there was a lot of criticism regarding how the bridge was restored and that it was not original. Did you receive any criticism from anyone regarding the reconstruction of the bridge?


No criticism.  The public is excited to have the bridge back in place. 


7. Referring to the comparison of the two bridges, in your opinion, do you think truss bridges are making their way back to the scene as a structure of choice for vehicular traffic?


 My expertise is not that large.  We wanted the Motor Mill Bridge to look like the historical pin connected Pratt through truss bridge.

Author’s note: This will justify a question for the larger forum to be presented after the Historic Bridge Weekend in August.


8. How has the public received this finished piece of artwork?


We have had one marriage proposal and a set of prom pictures taken on the bridge in the first 5 months of the bridge being open.  I believe this speaks for itself.

Author’s note: One note is the fact that many bridge enthusiasts will be visiting the bridge in August during the Historic Bridge Weekend, specifically on Friday the 9th of August between 2:00 and 2:30pm. If interested, please contact Jason Smith at the Chronicles or just stop there at that time.


9. If one wants to see the bridge, how to get there from Elkader?

  From Elkader head south on Hwy 13, turn left onto Grandview Rd.  Then a left on Hazel, a left on Galaxy to the Motor Mill site.  The Park is well signed from Hwy 13.

You can also find the info and GPS coordinates here.

The replica version of Motor Mill Bridge. Can you see the differences between the one photographed by J.R. Manning and the original provided by Hank Zaletel?

Happy Fourth of July 2013

Wabasha Bridge over the Mississippi River Photo taken in Sept. 2010







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Fourth of July- the time to celebrate the birth of America. It started with the Declaration of Independence on this day in 1776; 11 years later came the Constitution creating the Republic to which it still stands today. Many historic landmarks still stand today, constructed by many architects and engineers wanting to leave their mark for future Americans to see.

Irene Hixson Bridge, located over I-94 west of Loring Park in Minneapolis, built by Siah Armajani in 1988. Photo taken in 2009.

This applies to bridges as well, for many engineers, whether it was John Roebling, Lawrence Johnson and Gustav Lindenthal, who immigrated from Germany, Ralph Mojeski,  who originated from Poland,  Salvador Calatrava, who was a Spaniard or even Siah Armajani, who gave up his Iranian citizenship to live the American Dream, left their marks on their bridge design and construction for  people to see today. Most of them have been listed on the National Register of Historic Places; some will eventually be listed in the near future because of their design and the example of how these people came to the States to allow for their creativity and fantasy to run wild. Many engineers used Erector sets to draft their dream bridges before building them. Others improvised and built bridges that made people wonder in awe. In any case, many of today’s bridge builders have used the examples of bridges built in the US as a source of inspiration, despite attempts by politicians and agencies alike to have a plain bridge built in the shortest time possible at the cheapest cost- a logic that has caused many in the bridge, preservation and engineering communities to scratch their heads and question their logic. Bridges are meant to carry traffic and goods from point A to point B, yet when they are rendered obsolete, they are meant to be used as a historic marker, recognizing the tire and toil put in by engineers and bridge builders when it was built in the first place, and to be given new life for those engaging in recreational activities, such as biking, walking, jogging, etc.

The Smithfield Street Bridge in Pittsburgh, the best example of a piece of work built by Gustav Lindenthal built in 1883. Photo taken in August 2010

So that’s why we are here to celebrate the Fourth- in style. Many bridges are part of the festivities including fireworks, dances and boat rides, like the bridge over the Mississippi River in Wabasha, Minnesota, for example. Other bridges are the focus of private venues, for fishing, grilling or just being alone to watch the sunset, a prerequisite to the fireworks that go off on the eve of dusk.  In either case, when you cross a bridge this evening, built by an engineering great, think about the hard work put into building the structure and how it became part of America’s infrastructural history, which seems to be mutating at high speeds, from the first primitive crossings, to the ones built of iron and steel, to the ones that are becoming fancier to see. We must take pride in our work and consider that it is not necessary to have such a plain ugly bridge, but to have one that is a work of art, both past and present, for generations of the future to see as they cross it.

Janesville Bridge over the Cedar River at the Bremer/ Black Hawk County border in Iowa. Photo taken in September 2010

The Chronicle’s questions for the Forum (for you to post either in the Comment section of this article or on the facebook page):

1.       Which bridge do you know is the site of the Fourth of July Celebrations or can be seen during the fireworks display?

2.       Which bridge is your favorite place to visit and do during the summer?

The Bridgehunter’s Chronicles and its sister column the Flensburg Files would like to wish everyone a happy but safe Fourth of July weekend, no matter where you go and what you plan on doing for the weekend.

Canadian Bridges washed away






Unprecedented Flooding in Alberta, Manitoba and Saskatchewan, and with that several bridges gone

Of all the areas in the world that have been prone to flooding over the last 15 years, including those along major rivers, western Canada was one of the places where flooding was least expected. During the time span between the 20th of June and present,  many small to medium sized rivers became large bodies of water, with raging rapids and mudslides, taking towns and large cities by surprise, when no one expected it. For many regions, this is the worst flooding since the 2005 Floods, which was considered the 100-year flood.   The hardest hit areas were places in the Provinces of Saskatchewan and Alberta, where many communities located next to rivers were underwater in a matter of minutes. All of Calgary, the city of 3 million inhabitants located at the junction of the Bow and Elbow Rivers was flooded out (as seen in a video clip shown here), with other communities, like Medicine Hat, Canmore and High River sustaining considerable flood damage despite people fighting to keep the floodwaters in the river. The cost of repairs and reconstruction is expected to be in the billions of US Dollars and like the areas in Europe that are drying out from their Great Flood, Canada will most likely enter a recession for cities like Calgary, considered engines for economic growth, will suffer from millions of Dollars in lost revenue.

The unexpected flooding wiped out many bridges in the region and caused considerable damage to others, some to a point of collapse. No matter whether they were pedestrian crossings, railroad bridges or even bridges being constructed, no bridge was safe from the raging waters of the swollen river unless they were inspected, rehabilitated or built higher than the dikes.  While some bridges, like the Finlay Bridge in Medicine Hat were spared flood damage, some, like the Bragg Creek Bridge near Calgary was used as a buttress to shred houses washed away as seen in the video. But unfortunately for many bridges, like the ones highlighted here in this article, they were not so lucky. Here are the highlights of some of the bridges reported that were affected by the floods in one way or another:

Bonnybrook Bridge undermined by flood waters, collapses

Many of Calgary’s bridges, both old and new, were damaged substantially, as the Bow and Elbow Rivers turned the metropolis into Venice, and the bridges were undermined either through the severe erosion of the abutments, a span or two being washed away, or in this case, water currents undermining one of the piers of the Bonnybrook Railroad Bridge, spanning the Bow River next to another bridge.  While the bridge was inspected 18 times during the floods, it would have needed a 19th or 20th check-up to see that the pier was instable enough to cause two spans of a five-span pony truss bridge to partially collapse on 27 June in the afternoon with train coaches parked on the bridge to hold down the weight. The owner of the bridge, Canadian Pacific (CP) worked with haste to pull the wagons off the bridge. Despite this questions are being raised as to whether the bridge inspections were thorough enough, and that the extra work would have been needed to see that something was seriously wrong with the 1920 structure. It is expected that a new bridge built 4-6 feet higher- just as high as its neighboring bridge located 150 feet from the collapsed span- will be needed to accomodate rail traffic. A link to the story with videos can be found here. More information on the fate of the Bonnybrook Bridge will come here on the Chronicles.

Fish Creek Provincial Park and Bridges a total loss

Many pedestrian bridges including a pair of suspension bridges in and near Calgary were destroyed during the flooding. This include a couple at Fish Creek Provincial Park. Consisting of two sections straddling the Bow River featuring a dozen bridges, a zoo, golf course, bike trail and a natural area, this area was no stranger to disasters, for seven bridges on the western section of the park were wiped out during the 2005 floods and had to be replaced. Even though they were for the most part spared the flooding, three bridges were severely damaged or were destroyed this time around. This includes a bridge whose structure and abutment were completely washed away down the river, and a newly built MacKenzie Pedestrian Bridge, built in 2007. All that is left of the bridge is its Warren through truss span above the river as the approach and abutments were washed away. Another pedestrian bridge near the park, a beam bridge, suffered a similar fate. The cost of repairing or replacing the bridge represents a fraction of the cost for rebuilding the park, which is expected to be in the millions of US Dollars and will take at least 1-2 years to be fully restored. More information about the park and the bridges can be found here.

Bragg Creek Bridge survives onslaught of floating house

While this bridge represents an example of a bland plain grey concrete bridge built a few years ago to replace a previous structure, this structure made headlines in another way, for a spectator filmed a two-story house that had been washed into the creek and was floating at over 80 kilometers per hour when it encountered the structure and its center pier. Upon impact, the house was reduced to a pile of rubble. While the damage to the bridge was only slight, the owner of the house will have to go to the drawing board to design a new house.  A video of the impact can be viewed here.

To summarize the whole event in one sentence would be difficult except to say that the region is a whole mess right now, and people are working to rebuild their livelihoods. A difficult road is ahead of them for many homes, buildings and even bridges, damaged by the floods may have to be torn down and replaced. Already there was talk of Calgary tearing down over 100 buildings damaged by flooding. Yet this is only part of the rebuilding process as local and provincial governments and residents alike are working to ensure that the next flood of biblical proportions will not destroy the region again, for the third time may force many to leave the region for good. However, such preventive measures will come at a price, which includes redrawing the landscape and infrasturcture to ensure a three-peat will never happen.

Flood Aftermath in Europe

All photos courtesy of the City of Linz

Produced together with sister column: The Flensburg Files

Clean-up of flooded areas underway. Several small crossings destroyed by flooding, mostly concrete beam bridges. Others doomed due to damage. Linz Railroad Bridge spared flooding and near ship mishap but fate sealed?

Four weeks where fields became lakes, towns became small Italian villages, and farmers and merchants became gondola drivers and boaters. That is the signature of the Great Flood of 2013 in central Europe.  Heavy rainfall caused several major rivers in Germany, Austria, Czech Republic, Hungary and other countries to flood their banks, setting new records, destroying livelihoods and causing damages that are exorbitant financially and in a literal sense. In Germany alone, 10 out of 16 states were declared disaster areas, with the hardest hit areas being in Bavaria, Saxony, Saxony-Anhalt and Lower Saxony. Cities, like Passau, Halle (Saale), Magdeburg and Luneberg broke 400-500 year old records with much of the city being under water.

But surprisingly according to newspaper reports, unlike the Great Flood of 2002, damages to the bridges in Europe were minimal. While many smaller bridges were destroyed because of flash floods, the major bridges along the Saale, Elbe, Danube and Rhine Rivers (among them) sustained little to moderate damage. This is a stark contrast to what happened in 2002, where many major crossings were damaged to a point where demolition and replacement were warranted. This included the Pöppelmann Bridge in Grimma (Saxony), a 1719 stone arch bridge that was undermined in the 2002 flooding and had to be rebuilt. While Grimma was flooded out again this time around, the bridge survived the flood thanks in part to the main span allowing water to pass through.

Old Magdeburg Railroad Bridge spanning the Elbe- Photo taken in February 2011

But it does not mean that the bridges that survived the floods and mudslides are safe. Many bridges are being inspected to ensure they are safe for travelling. This includes the Elbe River crossings between Magdeburg and Lauenburg, where the Elbe put hundreds of miles of highways and rail lines underwater together with the bridges. While bridges like the historic Anna Ebert Bridge in Magdeburg are being inspected for structural concerns to determine whether street cars can use it again, it is possible that an even bigger solution to the flooding problem will come at the expense of these crossings as many local and state government officials are looking at all options possible to ensure that the next round of floodwaters stay in the rivers and not flood the banks. This includes raising some bridges and rebuilding and removing those that are hindering the flow of water. This puts such crossings like this and  the old railroad bridge over the Old Elbe River located downstream from the Anna Ebert Bridge, at risk. A link to the bridges of Magdeburg is here if you wish to look at the city’s bridges and their history.

Anne Ebert Bridge- Photo taken in February 2011

One of the interesting facts about this round of floods is the fact that not only the small river crossings were undermined and destroyed by flood waters, but the majority of the bridges destroyed in the floods were concrete beam bridges built between the 1980s and 2000s. This is unusual given the fact that beam bridges were built to allow river currents to flow over and underneath the structure. But as you can see in a video of a beam bridge being washed away in Poland two weeks prior to the Great Flood, if the river current is strong enough, it can cause the span to sag and eventually break it apart and wash it away. You can see the full video here. This was exactly what happened to the bridges in eastern Thuringia and western Saxony in the area of Zwickau and Chemnitz, as these crossings were either wiped out or damaged to a point where replacement is now a necessity. Even if beam bridges are made of wood and steel, many of them crossing these small streams were wiped out or barely survived but are not stable enough to be repaired. This will most likely lead to the question of which other bridge types to be used when these structures are being replaced, for many arch, suspension, cable-stayed and truss bridges survived the onslaught of flood waters with little or no damage. Interestingly enough, these types are being used more extensively for bridge construction here in Europe than beam bridges, which should put other countries (like the US and Canada), their agencies, politicians and bridge builders on notice regarding bridges to be used not only to accommodate traffic across ravines but also be structurally sound against such natural disasters.

To close this series on bridge disasters and the Great Flood of 2013, there are a couple interesting bridge stories to mention that provide some lessons in dollars and sense. One deals with preventive measures to keep a temporary bridge from being washed away at the cost of many thousands of Euros. Another bridge survived a near boat mishap, to the dismay of the majority of the community the bridge is located, for the 110-year old structure is due for replacement but is protected by federal preservation laws, which officials are pursuing to have this protection revoke to allow for the bridge replacement to proceed.  Here are the details:

Flood destroys new bridge abutments and temporary bridge in Zschopau, Saxony:

Many small bridges along this small river in western Saxony were severely damaged or destroyed during the floods. This bridge is one of them. Located along the Zschopau River in the town bearing the river’s name, near Chemitz, the Bailey pony truss bridge was supposed to serve as a temporary crossing as a new bridge was being built replacing a two-span brick arch bridge. Yet misunderstanding plus political inaction and rushing water doomed the temporary bridge as the floods not only destroyed the bridge, but also the abutments of the new bridge being built. This created a stir among residents who were against the construction of a new bridge and had pushed to temporarily remove the Bailey truss from the river, both unfortunately to no avail. The bridge has long since been fished out of the river, and a new temporary bridge is planned at the moment, but at costs that would have been avoided had action been taken earlier.  As for the new bridge, it is unknown when it will be completed for construction crews will have to build a new bridge completely from scratch, even revising their plans to ensure that the structure will survive such onslaughts as this one. An article on the bridge can be found here.

Linz Railroad Bridge survives flood and close call:

Never has there been such discontent towards a bridge as the city of Linz in Austria. As reported last year, the three-span through truss bridge spanning the Danube River has been targeted for demolition and replacement by politicians and the majority of the community, even after a pair of reports indicated that half of the bridge cannot be restored. Yet this 1903 structure has been protected by the Austrian Heritage Laws because of its historic significance to the region and its rare truss type that was used in bridge construction in Austria. This bridge survived a close call as a small ship traveling along the high flowing Danube River almost rammed into the bridge. However, this was not before having to evacuate 120 Swiss tourists ashore prior to its passage. The ship barely made it across the rising river. A few more centimeters and a collision with the truss bridge would have been likely, causing damage to both the boat and the structure. An article on this incident can be found here.  While many were wishing that the accident would have happened and the bridge would have either collapsed or been damaged to a point of irreparably, government officials, which includes the city council, the mayor of Linz and the railroad company that runs trains across the bridge have filed a petition to the Austrian Heritage Office in Vienna to have its historic status revoked, so that the replacement of the bridge could proceed at the earliest in 2014. While the decision was expected last month, there is still no word on whether this waiver will be granted. If the request is denied, the city and the railroad will be forced to consider alternatives, which includes rehabilitating the entire structure. This will take twice as long as the two years needed to replace the bridge. More information on this bridge can be found through the OÖ Nachricht here as well as through the Chronicles, here, which will keep you posted on the latest on this bridge. An organization aimed to save the bridge has been created. You can find them by clicking on here.

Our last part of the Flood Series focuses on Canada and its acute flooding situation which has ripped railroads out of their beds and dropped many important crossings into the water, including the ones in the Provinces of Alberta and Saskatchewan. Stay tuned!

You can view the highlights of the Great Flood of 2013 in Europe through sister column the Flensburg Files, which you can click on here.