In 2006, the Office of Inspector General, which is part of the U.S. Department of Transportation, completed an audit entitled "Oversight of Load Rating of Structurally Deficient National Highway System (NHS) Bridges."
Jon Nekritz, P.E., division bridge engineer for the Federal Highway Administration (FHWA) Michigan Division, told attendees of the 2008 Michigan Bridge Conference held recently in Mount Pleasant that OIG developed several recommendations. OIG reported that FHWA needs to work to maintain better up-to-date bridge ratings and accurate load postings. "They also wanted FHWA to evaluate greater use of bridge management systems to improve inspections and load ratings. So, that all leads to greater oversight of load ratings on the FHWA's part," Nekritz said.
Nekritz reported that OIG is not directly involved in the Interstate 35W bridge collapse investigation in Minnesota; however, the agency is re-opening its 2006 audit to see what corrective actions FHWA has taken on load ratings and postings. They will also be looking at the effectiveness and efficiency of federal funds to repair and replace structurally deficient bridges.
As a result of the collapse of the Interstate 35W bridge in Minnesota, the U.S. Government Accountability Office (GAO) is looking into bridge condition trends and the data used to determine that condition, Nekritz said. The agency is also looking at the criteria and processes to prioritize bridge conditions.
"The GAO is also looking at sources and amounts of federal, state and local funding for bridges. I think that it's good that they are looking at all of the money going to bridges, not just federal funds," Nekritz said. GAO is also looking for recommendations to improve the bridge program, Nekritz pointed out.
The National Bridge Inspection Standards (NBIS) were modified in January 2005 with the intent to be fully implemented one year later. Section 615.313 (inspection procedures) covers the requirements for scour evaluation. All bridges over waterways must be evaluated for scour vulnerability.
"This has long been an FHWA policy and it's been in the American Association of State Highway and Transportation Officials' guidance for a long time. We are tracking this through the National Bridge Inventory item 113," Nekritz said.
"The NBIS also has a requirement to develop plans of action for all scour-critical bridges. In January, our Washington, D.C. office provided direction to our state division offices that we needed to verify the status of scour evaluations and the status of implementation of plans of action. They further directed that if evaluations were not completed that we needed to notify our states that they are not in compliance with the scour provisions of the NBIS and that noncompliance will lead to suspension of federal aid. They strongly recommended short-term target dates for completion of these plans of action. The majority of bridges in Michigan have been evaluated; however, we still have a significant number that have not been evaluated, particularly at the local agency level. Over 1,700 county bridges and nearly 300 city bridges have not been evaluated for scour. This adds up to nearly one-third of the bridges over waterways in Michigan that have not been evaluated."
Scour-critical bridges are bridges over waterways that are vulnerable to a flood condition and unstable.
Nekritz said that 550 bridges in Michigan are known to be scour-critical. "The Michigan Department of Transportation (MDOT) has developed a plan of action process and they have developed some procedures to go along with it. MDOT has also implemented a small number of plans of action using this recently developed process. However, we are not aware of any plans of action developed by local agencies. Upon completion of the scour evaluations, we expect that there will be more than 550 scour-critical bridges in Michigan," Nekritz said.
"We sent a letter to MDOT Director Kirk Steudle in the middle of February informing him that Michigan is not in compliance with the NBIS scour requirements. We have requested a response from MDOT that addresses the schedule for completion of scour evaluations, completion of plans of action, actions that they will be taking to address these problems, and regular status reports on the progress of plans of action."
Nekritz said that MDOT is responding to FHWA. "I think that it's safe to say that MDOT will be providing further direction to local agencies in the near future. FHWA and MDOT will be agreeing on targets for scour evaluation completion and completion of plans of action. You can expect them to be short-term. Further direction will be coming and we will be monitoring progress in this area," Nekritz said.
"We're not out to suspend federal aid funds. That's the last thing we want to do, yet it is our only hammer to see that it gets done."
"MDOT is responding to FHWA with target dates that we feel MDOT can achieve, and the vast majority of local agencies will be able to complete their scour evaluations and complete their plans of action. The dates we are putting in our letter to FHWA are the end of 2009 for completing evaluations and the end of 2010 for completing the plans of action," David Juntunen, P.E., engineer of Bridge Operations for MDOT, said.
Chris Gilbertson, P.E., research engineer at Michigan Technological University, told attendees that sustainable bridge design and construction is still in its infancy.
Sustainable practices focus on providing what is needed for today and the future. Life cycle costs are key to focusing on a better use of materials and design by realizing the long term value of high-performance materials that may or may not initially cost more. Proper material selection helps meet the goal of attaining the design service life with proper maintenance but without major repairs.
"The reason for its importance is that we have a growing need for sustainability. In the last 100 years, the world's population has increased by four times. Along with that, we're using water at nine times the rate that we were 100 years ago. We have 13 times the production of sulfur dioxide and 14 times the production of carbon dioxide. So we're consuming a lot more and producing a lot more waste than we have in the past," Gilbertson said.
"Over 10 years ago, FHWA reported that in order to take the next step to a more sustainable transportation infrastructure, we need to do things in a different manner. One of the important tasks is to look at how we select our material. What's the most appropriate material for the most appropriate location? How do we take the greatest benefit that a particular material offers and apply it to the situation that we need the most? In the end, what you would like to do is build longer bridge spans, which cuts back on the amount of piers; use less material by producing smaller section sizes for the same road capacity; use higher strength concrete and have a higher strength-to-weight ratio, which cuts back on materials.
"Reducing life cycle costs is a large factor because then we are producing bridges that last longer and require less maintenance over time. Therefore, there are significant savings in all aspects of sustainability."