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Texas Bridge Inspections, Repairs Accelerated Following Minnesota Collapse

08/06/2008

August 1, 2008 marked the one-year anniversary of the collapse of the I-35W bridge over the Mississippi River in Minneapolis, Minnesota that killed 13 people. That tragedy prompted the Federal Highway Administration to urge state transportation agencies to inspect all steel deck truss bridges similar to the failed Minneapolis bridge.

Over the last year, Texas has spent over $334 million to replace, rehabilitate, and maintain its bridges. There are over 50,000 bridges in Texas, including 309 steel truss bridges. All bridges are inspected at least once every two years.

Based on the results of the inspections, Texas bridges are targeted for replacement or rehabilitation by using a prioritization score. The scoring system is based on addressing those bridges most in need first. A bridge’s score takes into account many factors, including traffic; federal sufficiency rating; and the condition of the deck, substructure and superstructure. In fiscal year 2009, Texas has been provided an additional funding obligation of $32 million by the Federal Highway Administration to address eligible bridges.

Of the 50,495 bridges in Texas, 1,841 are rated “structurally deficient.” Bridges identified as “structurally deficient” need monitoring, with parts that need repair or replacement. If a bridge is found to be unsafe, it is closed to traffic. Krista Piferrer, spokeswoman for the Governor’s office, emphasized, “The bottom line is, if any bridge in Texas is deemed dangerous, we’re going to close it.”

Within three weeks of the Minnesota collapse, TxDOT employees had targeted six steel deck truss bridges for critical inspections. Those inspections revealed two bridges that required attention and repair – one on SH 174 over the Brazos River near Waco, and the other over the Clear Fork of the Trinity River in Fort Worth. Repairs to the SH 174 bridge were completed in 2007, and repairs to the Clear Fork bridge will begin in the fall.

In the wake of the tragedy, TxDOT also established procedures to evaluate the gussets on truss bridges and developed construction specifications that address the requirements to store materials on bridges during construction. Although a final determination has not been made, authorities suspect that the collapse of the Minneapolis bridge was related to an original design flaw. Gussets – steel plates that fasten the trusses together at joints – were too thin to handle the traffic load. Contributing to that, they suspect, was the nearly 600,000 pounds of construction supplies and equipment stored on the bridge at the time.

The Texas Department of Transportation has prioritized funding to ensure that the state’s highway system remains safe, that we protect our investment in our current infrastructure, and that we provide for the mobility needs of a growing population. The bridge program is a significant part of the plan, and the additional funding provided by the Federal Highway Administration will help repair or replace critical bridges across the state. It is TxDOT’s goal to have 80 percent of all bridges in the state rated as good or better by 2011.

Texas Bridge Index

Total number of bridges in Texas as of July 2007: 50,183
Total number of bridges in Texas as of July 2008: 50,495
Number of steel truss-type bridges of same design as the one in Minnesota: 6
Number of bridges rated as “structurally deficient” as of July 2007: 2,024
Number of bridges rated as “structurally deficient” as of July 2008: 1,871
Percent of bridges in Texas rated as structurally deficient in July 2007: 4
Percent of bridges rated as structurally deficient in May 2008: 3.6
Bridges replaced from August 2007 to August 2008: 209
Cost to replace those bridges: $254.3 million
Bridges widened or rehabilitated from August 2007 to August 2008: 89
Cost to rehabilitate those bridges: $69.3 million
Cost of maintenance on 165 bridges in one year: $10.5 million