Minnesota Governor Addresses I-35W Bridge Collapse

ST. PAUL, Minn. - On August 2,Governor Tim Pawlenty directed Mn/DOT to take several actions to address issues related to the I-35W bridge collapse: 1. Mn/DOT will hire Wiss, Janney, Elstner Associates, Inc., a forensic engineering firm, to do an independent investigation of the cause of the collapse. This effort will be in cooperation with the National Transportation Safety Board which will conduct its own investigation to determine what led to the collapse of the bridge. 2. Mn/DOT will hire an independent firm to review bridge inspection processes and protocols used in the state. 3. Mn/DOT will conduct an emergency inspection, in priority order, of all bridges that have the same deficiency rating as the I-35W bridge, beginning with the three Minnesota bridges that have the same arch deck truss design as the collapsed bridge. These bridges are Highway 23 over the Mississippi River in St. Cloud, Highway 123 over the Kettle River in Sandstone and Highway 243 over the St. Croix River to Osceola, Wisconsin. Governor Pawlenty also said that National Transportation Safety Board will conduct its own investigation to determine what led to the collapse of the bridge. Bob McFarlin, Mn/DOT's Assistant to the Commissioner for Policy and Public Affairs said, "On behalf of Lt. Gov./Transportation Commissioner Carol Molnau and everyone at Mn/DOT, we extend our deepest condolences to the family and friends of those affected by this catastrophe." Mn/DOT Bridge Engineer Dan Dorgan spoke about Mn/DOT's inspection practices and the history of inspections on the I-35W bridge. Tom Everett, structural engineer from the Federal Highway Administration in Washington D.C. provided an explanation of the term "structurally deficient." He said that this is a programmatic classification and not a reference to safety. Khani Sahebjam, Mn/DOT Metro Division Engineer, talked about work that was being done on the bridge at the time of the collapse--a $9 million project to do patching, concrete overlay and joint repair. Overall Facts about I-35 Bridge Collapse, Minneapolis, MN: Structurally Deficient Structurally deficient means there are elements of the bridge that need to be monitored and/or repaired. The fact that a bridge is "deficient" does not imply that it is likely to collapse or that it is unsafe. It means they must be monitored, inspected and maintained. Most deficient" bridges are left open to traffic while it undergoes maintenance and repair. If inspectors find unsafe conditions they will restrict access or close the bridge. Nothing in the inspection reports indicated that it was necessary to limit access or close the I-35 Bridge. Inspection History and Results The I-35 bridge has been inspected annually by MnDOT A recent inspection was conducted by MnDOT on May 2, 2007, to address some minor concerns regarding weld details. MnDOT planned to continue inspecting the bridge in the fall. No imminent dangers were observed. Prior to that inspection, the bridge was inspected in June 2006. The bridge was rated 4 over all. The 4 rating means that the state can continue to operate the bridge without load restrictions (0= shut down, 9 = perfect). Background The National Bridge Inspection Program: · The National Bridge Inspection Standards (NBIS), in place since the early 1970s, requires biennial safety inspections for bridges in excess of approximately 20 feet in total length on public roads. · Safety is ensured through hands-on inspections and rating of components, such as the deck, superstructure, and sub-structure. This composition and condition information is maintained in the national bridge inventory (NBI) database, maintained by the FHWA. · Certain structures can be inspected every 4 years if they are deemed to be in very good condition. Approximately 83 percent of bridges are inspected once every 2 years, 12 percent are inspected annually, and 5 percent are inspected on a 4 year cycle. · Over $4 billion is apportioned annually from the Federal government to State DOTs for bridge replacement, rehabilitation and preventative maintenance. Bridge Facts: Opened in November 1967 Dimensions: Length: 1907 ft (structure length; 458 ft (length of max. span) Width: 8 traffic lanes, 108 ft Height: 64 ft above water Location: I-35 West at Mississippi River mile marker 853.20 and 1 mile northeast of junction TH94 Type structure: Steel Arch Deck Truss This bridge is unique because it was constructed with a single 458 ft steel arch to avoid putting piers in the water which would impede river navigation. Daily Traffic: 141,000 vehicles per day as of 2004 count. Detour status: MnDOT has a detour in place and expects it to minimally impact traffic. On August 3, 2007, inspection begins on the three bridges that have the same arch deck truss design as the collapsed I-35W bridge. These bridges are Highway 23 over the Mississippi River in St. Cloud, Highway 123 over the Kettle River in Sandstone and Highway 243 over the St. Croix River to Osceola, Wisc. Inspectors will evaluate bridge geometries and fracture critical members for any changes in condition from previous inspection findings. Mn/DOT has identified a fourth arch deck truss design bridge-the 1st Street South bridge in Sauk Rapids. Inspection on this bridge will begin on August 4. U.S. DOT Secretary Mary Peters has ordered all states to inspect deck-truss bridges. The four bridges mentioned above are included on that list. Mn/DOT has begun the process of identifying a consulting company that will review Mn/DOTs inspection practices and procedures. This consultant will also assist with inspection of priority bridges to be inspected across the state beginning next week. Mn/DOT will generate a list of these priorities based on factors such as fracture critical status, sufficiency ratings, critical deficiencies and average daily traffic. Two consulting firms- Wiss Janney Elstner and Lichtenstein & Assoc.--are on site. They are developing a plan for a forensic analysis of the cause of the bridge collapse that is expected to be finalized today. They will share this plan with the National Transportation Safety Board. They will focus their initial efforts on opening up the river channel for navigation as soon as possible. Approximately five Mn/DOT structural engineers are assisting with recovery efforts. Theyre working with other structural engineers to assess the structural integrity of the bridge wreckage and to identify safe locations for divers and emergency services teams to enter the water for their recovery work. Mn/DOT announced that John Chiglo has been named the project manager to lead reconstruction of the I-35W bridge. Chiglo, currently project manager for the Highway 212 construction project, is forming a team to begin work on the planning process. The bridge may be a design-build project in order to accelerate construction and assure quality on the project.