It was a day like no other in the summer time: thousands of people leaving their workplaces to get home with others taking their children to a baseball game in the middle of the city. It was a hot summer afternoon and traffic was dense, with tempers flaring from people who are late for a meeting or other commitment. As they head into the city, they cross a gigantic bridge over a mighty river, only to find that the second they got on, they ended up in the water, swimming for their lives and helping others in need. Eyewitnesses videotaping the bridge saw each span falling into the water, one after the other.
The St. Anthony’s Bridge in Minneapolis, Minnesota (USA), a steel deck cantilever truss bridge over the Mississippi River carrying the freeway I-35W was one of the most travelled bridges in the Twin Cities. Built in 1967, it served one of the main arteries and was undergoing some maintenance work, when it collapsed. 13 people died in the tragedy, more than 150 people were injured and that particular artery going through Minneapolis was cut off for over a year and a half while a new bridge was being built.
Five years later, a lot has changed. The disaster served as a wake-up call for the US, with hundreds of billions of dollars being spent on improving the infrastructure, replacing bridges deemed structurally deficient and making the highway system “safe and sound,” the term coined by the Missouri Department of Transportation and the title of its program. Yet we still have a lot of deficiencies that we need to work on in order to ensure that we have a sound infrastructure but not at the expense of historic bridges and the bank.
For instance, the Minneapolis bridge disaster sparked a crusade to eliminate truss and cantilever truss bridges- or at least those with ineffective gusset plates. It started in Minnesota and worked its way to other parts of the country, like Pennsylvania, which has one of the highest numbers of truss and cantilever bridges in the country. Instead of replacing the ones that desperately needed it, many them were wrongfully replaced when they were in pristine condition, and even if there were some defective gusset plates, these could easily be replaced without having to bring the entire structure down using falsework for support. This includes the two cantilever bridges over the Mississippi River in St. Cloud: the Granite City Bridge (replaced in 2008) and the Sauk Rapids Bridge (replaced that same year as well). This crusade has accelerated the decrease in the number of historic bridges built prior to 1950 nationwide, despite attempts on the part of the state and local agencies and private sectors to save the ones that have the greatest historical significance in terms of design, history and other factors.
The collapse also created an enormous backlash on the preservation community and the Preservation Policies, such as Section 106 of the Historic Preservation Laws of 1966, where bridges slated for demolition are to undergo environmental and mitigation surveys to determine the alternatives to demolition and document the structures’ historic significance. Many politicians have touted this policy as a waste of time and money and would like to see it scrapped, while many preservationists and pontists have taken substantial amounts of heat for interfering with progress and being “trouble-makers.” The fortunate part is with the economic crisis in the USA, there has been a change in heart among many who would like to see historic bridges preserved and have embraced some of the preservation practices as a way of saving money and prolonging their lifespan.
Then we have the financial aspect, where many bridges that were structurally deficient but not in danger of collapse are being replaced outright, without consideration of the costs. As a general rule, replacement is more expensive than restoration and rehabilitation, pending on the type of work needed to be done on the bridge let alone the type of bridge. When the I-35W Bridge collapsed, there was a consensus that every bridge that is structurally deficient needs to be replaced. The problem with that draconian approach is that it has been draining the financial resources on both the state and federal levels to a point where many of the bridges that have been deteriorating to a point where repairs are necessary had to be closed off to all traffic and the owners having to wait until funding is available to either fix or replace them. Some that can still carry traffic have weight and height restrictions on them, with some going to extremes by threatening motorists that the bridge would be closed to traffic if the restrictions are ignored.
But the collapse of the I-35W started a renaissance where the public has become more aware of not just the bridges that are structurally deficient and need repairs, but also those that are historically significant and should be restored for reuse. The media has taken a Steven Jobs approach and presented facts and figures that are either sobering to the public, who takes these figures seriously when presenting their opinions about historic bridge preservation vs. replacement or biased to one group or another in order for them to have things their way. What is meant by this is as these facts and figures are presented and there is a bridge in their vicinity that has weight and/or height restrictions on them, the public usually divides themselves up between those who want the bridge saved and those who want it replaced, thus becoming more involved in the decision-making process. The media has for the most part taken a neutral stance and has indirectly encouraged the public to engage more in these debates.
This public involvement has also spread into the social networks and produced online columns and blogs, where support for historic bridges is being garnered by people from faraway places. While bridge websites, such as James Baughn’s Bridgehunter, Nathan Holth’s HistoricBridges.org or Nic Janberg’s Structurae.net were established prior to the disaster, other online columns, like this one, Tony Dillon’s Indiana Bridges and Kaitlin O’shea-Healy’s Preservation in Pink have taken the stage to address the importance of historic bridges and ways to preserve them, research them to determine their historic significance and bring them and topics involving them to the attention of the public. Even organizations preserving historic bridges, like the Riverside Bridge (in Missouri) and the Waterford Bridge (south of Minneapolis) can be found on social networks, like facebook, and support for these bridges have come not only from within their vicinity, but also from outside as well. This has created an interdependence between the public, the media, and agencies and other organizations where action to preserve or replace a historic bridge has an impact on those who have a connection with them in one way or another. In the case of the Waterford and Riverside Bridges, support for preserving them have skyrocket by up to 200% in the past year, while the media and other historic bridge organizations have reinforced that support through their expertise and knowledge of the subject.
The disaster also fostered the need to exchange information and knowledge on historic bridge preservation. This includes the introduction of welding and other techniques to restoring a historic bridge presented by people, like Vern Mesler, who has held seminars like these in Michigan since 2009. Other steel companies, like BACH Steel, an ally of Julie Bowers and her organization, Workin Bridges in Iowa have engaged in disassembling and restoring metal bridges, while other companies dealing with bridge construction have taken a keen interest in this preservation practice. Many of the bridge companies mandated to replace historic bridges do not fancy destroying them in favor of progress and have become more open to other suggestions, such as relocation or storing them for reuse elsewhere. This was seen with the Upper Bluffton Bridge, where the contractors allowed for some time to see if the owners are willing to take at least part of the two-span truss bridge. The Queenpost truss span was taken in the end, while the Pratt through truss span had to be scrapped, despite the support to save the entire structure.
What has become the most useful of all is having historic bridge seminars and conferences, designed to present these themes- preservation, tourism and the bridges themselves and the stories about the successes- to the attention of the audience. This includes the Historic Bridge weekend, which was started in 2009 by Todd Wilson of Bridgemapper.com and features presentations by bridge experts and tours of bridges in the area of venue. The first two took place in the greater Pittsburgh area, last year’s conference took place in Missouri, while this year’s conference will take place in Indiana, one of the states with the most populous historic bridges in the country. Plans are in the making to host one in Iowa in August 2013. The number of people attending such events have increased since 2009, which is a sign that the interest in historic bridges and preservation is there, and as the news goes around, more people will attend these events to gather information and support for preserving their historic bridges in their communities or their backyard.
There is a reason for the need of such seminars and conferences: tourism. One may never think that historic bridges can be such a tourist attraction, but it is. With rails-to trails programs, many of the historic bridges that used to serve rail traffic are getting a new lease on life as a pedestrian bridge, many historic bridges are being relocated to trails and parks to serve both as an exhibit as well as crossing for cyclists and pedestrians. This includes the Historic Bridge Park in Michigan, the F.W. Kent Park in Iowa, and the Delphi Trail in Indiana, just to name a few. There are even parks where a historic bridge is their centerpiece, and the numbers are increasing. This goes beyond the ones that are in my neck of the woods, like the Freeport Bridge Park outside Decorah and the Moneek Bridge Park in Castalia, both in Winneshiek County, Iowa and the Covered Bridge Park in Zumbrota, Minnesota. These parks have provided tourists with an opportunity to get to know the structure and its role in the development of America’s infrastructure, while at the same time, many communities have cashed in from having these grandiose pieces of artwork, in one way or another.
Still despite all this, we are still lacking the educational aspect of preservation versus replacement, let alone learning to design a structure that is appealing to the public. That means that on the one hand, there is a lack of sufficient knowledge on how to preserve and maintain bridges with historic value because of the lack people with experience, combined with the lack of will to engage in preservation practices and the dollars and sense to preserve these structures. The mentality has been to fast-track as many bridge projects as possible so that they have the new structure in place as soon as possible, regardless of its appearance. Most of the bridges built today are bland and tasteless, and have a lifespan that is much shorter than the structures of yesterday (at least 70 years ago). Even the cable-stayed bridges, the norm for bridge construction, is not the permanent solution, as like beam, girder and slab bridges, their wear and tear can be seen more quickly because of weather extremities combined with traffic loads that are 10 times more than what we were used to 20 years ago. We need to veer away from the mentality that we need a bridge that lasts for 100 years and does not require maintenance and embrace in education on how to preserve historic bridges, how to maintain bridges, and how to design bridges that are appealing to the drivers but have no design flaws and are meant to last for more than 20 years. We also need to encourage more rail and public transport services to wean motorists away from the car and alleviate the load on our aging structures. We also need to enforce sanctions on people who violate the weight restrictions and destroy a bridge as a result. And most of all, politicians should take a backseat with regards to bridge preservation vs. replacement. We have capable bridge engineers, preservationists and bridge technicians who have the capabilities to determine which bridge needs repair work or replacement and which ones deserve to be restored for reuse. It is the job of the politicians not to interfere with these issues but foster them. We live in an interdependent society where the action of one affects all, and this holds true for historic bridges in the United States, which are decreasing by the dozens as each year passes.
To finish up on this piece, we have to say that we have learned a great deal from the disaster of five years ago. We know what the main causes of the disaster were. We know that we can never afford to repeat this again. Yet we know that there is a right and a wrong way of treating this issue- bridge design, bridge construction, bridge maintenance, and bridge preservation. We know that the public has a very keen interest in this subject. And as we cross the new I-35W Bridge in Minneapolis, looking at the neighboring 10th Avenue Bridge, a concrete arch bridge built in the 1920s, we know how to get it done. It is just a matter of listening and learning from others and taking the right course of action to ensure the all will be happy with the results.
There are a lot of reactions to the five-year anniversary of the I-35W Bridge Disaster, but some examples are posted in the next article.