Identify what you consider to be the most important issue or topic associated with historic bridges and transportation project delivery. Please make your response as concise as possible, but do explain why you selected the issue or topic.
Terry H. Klein, SRI Foundation
Level the playing field between rehab and replace
It is clear to me that we do not choose to rehab even when it is the rational, feasible, and economic alternative. Why is that? There are real forces that produce the outcome of choosing replacement over rehab. What are those forces? One is policy, but most in the industry would say the policies are even-handed. Another is the engineering design paradigm. Another is the rigid interpretation and enforcement of guidelines (e.g. geometrics) with the unwillingness to choose design exceptions. Whatever they are, the forces need to be identified.
1.) AMEND NATIONAL HISTORIC BRIDGE PROGRAM (TITLE 23, SECTION 144(o), STURRA, 1987. The United States is notable as the only country with national legislation recognizing historic bridges, but it is at a critical turning point. Efforts over the last thirty years are slowly beginning to affect how old bridges are regarded, but it is not enough. Recent statistics suggest that half, if not more of our Nation’s historic bridges have been lost in the last thirty years - three decades in which transportation and preservation consciousness was at its highest level. This is an alarming and sobering statistic. While we are not quite at the threshold of saving "the few surviving examples," we are fast approaching that point. As a nation, the USA has yet to resolve how to save its historic bridges. Though its National Historic Bridge Program has been in place since 1987, until there is true leadership with specific legislation and funding incentives, bridges remain at risk. Without a coordinated national program to assess and preserve historic bridges, there is no imperative, practical or regulatory, to prioritize which bridges should be saved.
I tend to agree that 'purists' represent one end of the spectrum and that their adherence to fixed ideology can hinder a project. One example is the Texas SHPO wanting to preserve a guardrail made of gas pipe fittings that was 85% destroyed by corrosion.
But the other end of the spectrum is occupied by a large number of 'typical' engineers who have no conception or tolerance for anything outside the DOT standards book. Examples: Jersey barrirer rail, high-mast lighting, sight distances, etc....
One counter example on the rivets: we just bid a project, and out of the $1 million structural work on the 1881 trusses, the savings to use bolts instead of rivets was $7,000. In my experience, most truss bridge rehab projects are dominated by paint and railings and deck, not rivets, unless of course you are removing all of them.
I'll toss out two ideas for consideration related to project delivery.
Idea 1 - is the development of a national set of special provisions for historic bridges. I think there needs to be a set of special provisions developed for the rehabilitation of historic bridges that strikes a proper balance between NPS preservation briefs and typical DOT standard specifications for construction. The special provisions would help ensure owners aren't starting over from scratch when they try to put together specials for their projects. When the segmental concrete guys started the American Segmental Bridge Institute in an effort to get some market share. One of the very first things they did was to assemble standard contract documents so the owners had something to work with. Once there is some national consensus on what is expected in the specials, they could be sunsetted.
Idea 2 - is more theoretical in nature. Is it possible to use the design-build delivery method for the rehabilitation of historic bridges? I assume theoretically it is possible, but does anyone know of a project that used design-build?
Maybe preservation standards of care could be tiered similar to what is done for aesthetics.
Tier A - would be national landmark and state landmark structures where all means would be utilized
Tier B - would be slightly relaxed and be appropriate for structures on the national register
Tier C - would be relaxed a bit more and appropriate for structures eligible for the national register
Idea 1 is perfect.
Idea 2 is good, but I do not know which states allow DB delivery. I like it for rehab work, assuming the design professionals are qualified, so that might be a guidance document.
There is no agreement as to conditions under which truss bridges may continue in vehicular use. The collapse of 35W and heightened concern about fracture critical bridges carrying traffic complicates this. What width, load capacity, geometric and railing standards are acceptable under what circumstances? Those few states that have adopted minimal standards for low-volume bridges offer some flexibility, but it's limited.
Funding is the most important issue. Many times we knew what needed to be done to repair bridges but due to lack of funding we had to postpone the work. If the need became critical we had to close the bridge until funds were available. Most of the damage to historic bridges has resulted from lack of maintenance, particularily proper cleaning and painting. When I was rehabilitating bridges it had often been 30 years or more since they had been properly painted which resulted in corrosion in joints at pins or gussett plates
I did use a design-build contract to rehabilitate a historic covered bridge. We solicited letters of intrest from known experts in the field and asked for teams of experienced timberframers and engineers. The end product was praised by the Maryland Historic Trust.
State owned historic bridges are protected from immediate replacement. The historic bridges owned by counties and cities are not. I believe that education of elected and appointed officials and the PUBLIC of these realms is the most important first step in the preservation efforts. The many available avenues to " save a bridge " should explaned to them and the " SOB's " organanized.
After all the succesful rehabilitations of historic bridges that have been accomplished during the past 30 years or so we still hear from many bridge owners that "the bridge is old, has exceeded its useful life and needs to be replaced". Now with the tragic collapse of the I35 W. bridge in Minneapolis we are hearing that "we cannot consider the rehabilitation of this truss because it is "fracture critical', i.e. a loss of one main member may cause the collapse of the bridge as what occured on I35W.
I think some of us have learned that we need to not be dogmatic about our designs and insist on just "fixing what is broken", but rather we need to build in new when we can. We need many times to introduce new members to carry some or all of the loads, so that the owner has the confidence that we are not relying just on the existing bridge. We have done this for girder bridges, trusses and concrete arches. In order to save trusses we must eliminate fracture criticality by adding new members working with the old. Sure it will cost more but when we are done we have an existing bridge that is not working as hard as it used to and this makes it easier for many owners to approve.
Historians and those who have review approval from the environmental side need to understand that we cannot be "purists" and not change the look of the bridge, but must accept some visual changes as long as they are done in a sensitive nature. But as important , we engineers must be creative and bold enough to present these ideas and argue for their acceptance.
MoDOT boasts historic bridge is first to go with stimulus funds
“Missouri is the first state in the nation to begin construction on highway projects funded by the Economic Recovery Act. The minute President Obama signed the economic recovery bill, MoDOT went to work to replace one of the state’s oldest and most rickety bridges, the Osage River bridge near Tuscumbia.” (http://www.modot.org/FirstinNation/):
News article cites MoDOT as saying that its projects are on a "worst is first" priority. The Osage River bridge tops the list. David Cockrum, the bridge project manager, says there is no doubt the bridge needs to be replaced: "If you was to go up there and start kicking on that rebar up there, this is the stuff that would come down."
Besides the obvious funding issues, I feel that the most important issue is the one touched on by Frank Griggs: the issue of balancing "purity" of preservation with the need to accomodate modern traffic demands so that the structure can hopefully continue to remain in place and carry at least some sort of traffic. Bridges are engineering structures which were made to be used, and if we can't use them much of the potential reason and support for their preservation goes away. There is a limit to the number (and kind) of bridges that are suitable for, and deserving of, museum-quality restoration (despite some of the beautiful work that has been done on some park and museum structures). There are also relatively few localities and organizations which are able and willing to fund restorations of this kind. For perhaps the most popular example: if we can use high-strength bolts that resemble rivets, instead of actual rivets, for rehabilitation, and this results in the strengthening, preservation, and continued utilization of a number of historic bridges, isn't this preferable to losing all of these structures because using rivets (or other original technology) required expenses and technical issues that exceeded what was considered feasible for a rehabilitation project? Remember, the substitution of some materials and technology is relatively common in historic building rehabilitations--we seldom hand-forge all the replacement nails, we use steel, epoxy, and other non-period materials, etc.