Author’s Note: This article serves as a twofold function: 1. It is part of a multiple series on the Historic Bridge Conference, which took place last weekend (21-23 September) in Indiana, where the documentary was shown, and 2. This is the Bridgehunter’s Chronicles’ Book of the Month, but in a form of a DVD and documentary. An interview with Julie Bowers on historic bridge preservation was conducted earlier this year and can be viewed by clicking here.
There seems to be a belief from many people that historic metal truss bridges cannot be restored because the metal used for the structure has outlived its usefulness, and that restoration and/or relocation is either too expensive, outdated, or is not heard of. The last part was in connection with a comment made by a congresswoman in Ohio in May of this year.
Little do these critics realize is that restoration exists for metal truss bridges, and in the case of welding, the profession is making a comeback, as there is an increase in interest in this sort of work. And for the remaining truss bridges that are still standing in the country, this may be a blessing that could buck the trend of eliminating this truss type, especially after the I-35W Bridge Disaster of 2007 in Minneapolis, Minnesota (USA).
Using the Piano Bridge in Texas and the McIntyre Bowstring Arch Bridge in Iowa and with the support of songs by The Grateful Dead, Julie Bowers of Workin Bridges, a non-profit organization that deals with historic bridge restoration, produced a documentary on historic bridge restoration, bringing a profession back from the dead and, with step-by-step demonstrations and easy to explain concepts by the professionals, providing educational opportunities for welders, historians, agencies, bridge enthusiasts and people interested on how to restore a historic bridge.
The DVD starts with the McIntyre Bridge before and after the flood that destroyed the structure in August 2010 with the question of what to do with the structure. While Workin Bridges was in its infancy when this occurred, the organization’s biggest break came with the request from the people in Fayette County, Texas to restore the pin-connected Pratt through truss bridge, built in 1885 by the King Bridge Company of Cleveland, Ohio. Together with the Texas Department of Transportation (TxDOT) the restoration process started, first by taking the truss bridge off its original foundations, followed by taking it apart, putting rivets on the bridge, using heat to straighten out the eye bars, and doing other work with the parts, before putting the truss bridge together and placing it back on new foundations. The step-by-step process was filmed and photographed, with experts demonstrating to the viewer how these processes work, thus encouraging people to at least look at how restoration works, but with a long range goal of taking up the profession. Welding is an old technology that was developed in the 1800s, went into hibernation for many decades, but is making a comeback in a new form, which is restoring historic places made of metal. Yet for many people, the profession is new and exciting, but should be taken seriously, as it takes time and effort to form and reform structural parts to make a building or bridge look just like new.
Here are some interesting facts about welding that were in the film and are worth noting:
- Rivets are more effective than nuts and bolts in a way that they keep the metals intact and ensure that rust and weather extremities do not cause the metal parts to crack. One of the cracked parts discovered on the Piano Bridge led to the structure’s closing and the quest for someone to come and fix it.
- Heat stripping is a process of placing the torch on a section of metal, straightening it out with clamps.
- The Piano Bridge is made of wrought iron, which has a low heating temperature. Therefore, one needs to be careful not to have heat on a section of metal for a long time or else the material falls apart like wood. This contributed to many structures failing during the Great Chicago Fire on 3 October, 1871, which destroyed 80% of the entire city.
- Steel can be welded to wrought iron to ensure its stability for many years, despite claims that it can be bent to a point where it breaks.
- Most interesting fact: rehabilitating historic bridges means adding parts to support the structure. It does not mean restoration, as in taking apart and reassembling the structure.
While the welding process was progressing on the Piano Bridge, there were discussions about historic bridges and their fate, especially in connection with the I-35W Bridge Disaster. While many agencies have striven to have certain bridge types eliminated, as well as those that are structurally deficient, including those in Pennsylvania, Minnesota, Wisconsin and Ohio, for example, other agencies, like TxDOT have worked to find ways to restore historic bridges and/or relocate them for reuse if deemed necessary. It is part of a two-way approach where the costs are analyzed and engineering thought is put in to determine not whether a historic bridge can be restored but how. John Barton of TxDOT denounces the knee-jerk approach to historic bridge replacement, as it has happened in many places, but claims that engineering is a way to address the variables, both systematically and methodologically and should be taken seriously.
The film ends with some example bridges that have either been restored, like the State Street Bridge in Bridgeport, Michigan, or are targets for restoration efforts, like the Long Shoals Bridge in Kansas, the Cascade Bridge in Iowa, and the Enochs Knob Bridge in Missouri, the last two of which are being scheduled for demolition, although Workin Bridges is working to claim the Cascade Bridge to be restored. The Bridgehunter’s Chronicles will have that article for you as soon as the series on the Historic Bridge Conference in Indiana is finished. But it shows how each bridge could be restored thanks to the demonstrations that were presented in the film.
There are many demonstrations on welding techniques that are either available online or through seminars, like the annual welding seminar offered by Vern Mesler in Michigan. The DVD takes you up close to see how historic bridges can be restored through welding techniques that exist. It provides people with a chance to see how the process works and has the dos and don’ts to welding, let alone to restoring a historic bridge. Furthermore it advocates the need to do restoration work instead of rehabilitation, setting the standards very high for reasons of safety and integrity, while at the same time, restoring the bridge is more cost effective than rehabilitation or replacement.
The video is 47 minutes long and from a teacher’s point of view, if you have a class of students of civil engineering, conservation and restoration or even architecture, it is recommended that they see the film to provide them with a glimpse of the work and to spark their interest in possibly joining the profession, which has been growing since 2008. Chances are likely that at least a quarter of the students in the classroom will be interested in the work. And even if no one is interested in the profession and is only curious about how a bridge is restored, the content of the film is easy to understand and the demonstrations are up front and not too technical. For agencies and politicians who advocate bridge replacement, the DVD provides them with an alternative to demolition, convincing them that restoration is more cost effective and will prolong the life of a bridge for many decades to come.
I would like to end this review with a food for thought involving a question that I posed to many of my students: suppose you have a 120 year old truss bridge that is due for replacement and you have the following choices, which one would you take:
Replace the bridge with a concrete structure
Replace the bridge but leave the truss bridge in tact
Rehabilitate the truss bridge and leave it open to traffic?
Keep in mind the cost analysis for each option, the resources that are available, but most importantly, the interest of the people and their association with the structure. Without the interest, the truss bridge is history. Yet if the interest in saving the bridge is high, then one should look at the resources available and in particular, listen to the public and their suggestions. Chances are one of them may have seen this DVD and knows what he/she is talking about.
The DVD can also be viewed on YouTube, which you can watch below: