Saturday, August 4, 2007

Flaws found in many bridges

By Gordon Dickson, Anthony Spangler and Jeff Claassen - Star-Telegram staff writers - Fri, Aug. 03, 2007
Twenty-three bridges in Tarrant County fared worse in their most recent inspections than the bridge that collapsed Wednesday in Minneapolis, a Star-Telegram review of federal records shows.

A few have been repaired or replaced since the inspections. The low scores for the others don't necessarily mean the bridges are in danger of crumbling, officials cautioned.

"Texas bridges are safe," Randy Cox, director of the Texas Department of Transportation's bridge division, said Thursday. "If it gets to the point where we find a bridge can no longer safely handle a load, we close that bridge."

Nonetheless, inspectors hired by the state to conduct routine examinations of the bridges found an assortment of potential problems, including damage to piers, footings, railings and decks.

Some of the bridges are along busy commuting corridors, including:

The Texas 10 bridge over Northeast Loop 820 in Hurst, where motorists headed toward Hurst Boulevard or Baker Boulevard often feel the pavement shaking as big rigs roll by.

The historical Main Street bridge over the Trinity River near downtown Fort Worth, one of the region's oldest transportation landmarks.

The reports are included on a National Bridge Inventory database kept by the Federal Highway Administration. They include details of the most recent safety inspections, from 2004 to 2006. The database may not reflect current conditions.

The data show that 12.4 percent of the nation's nearly 600,000 bridges were rated "structurally deficient." In Texas, 4.5 percent of the nearly 50,000 bridges were deemed structurally deficient, as were 2.7 percent of Tarrant County's roughly 2,700 bridges.

The state Transportation Department declined to comment on specifics about the Tarrant County bridges. Agency officials said they have asked the state attorney general's office for an opinion as to whether bridge inspection records must be made public under freedom of information laws. The reports contain information that might help terrorists, a spokeswoman said.

Some of the bridges have been repaired, including a Keller Smithfield Road bridge in Keller and a Pipeline Road bridge in Hurst. At least one, the Duncan Perry Road bridge over Interstate 30 in Arlington, has been rebuilt.

Each bridge receives a sufficiency rating -- computed by a formula that considers dozens of factors noted during an inspection -- with scores from zero to 100. A score of 80 or less indicates some rehabilitation may be needed; a 50 or less indicates replacement may be in order. The Minneapolis bridge had a sufficiency rating of 50, according to federal bridge inventory data.

The data also rate a bridge's components on a scale of 0 to 9. A zero represents a failure, and a 9 is excellent; 6 is satisfactory; 5 is fair; 4 is poor; and 2 is critical.

Inspection ratings

The Minneapolis bridge was inspected in 2005 and scored a 4 for its structural members -- typically the support system between the pavement and the piers or footings.

It received a rating of 6 for its substructure, which includes "piers, abutments, piles, fenders, footings or other components," according to federal documentation. The deck -- or pavement, sidewalks and rails -- was rated 5.

The Star-Telegram reviewed records of more than 1,000 bridges in Tarrant County and found that 23 were considered structurally deficient and had earned sufficiency ratings lower than the Minneapolis bridge.

The Main Street bridge across the Trinity River in downtown Fort Worth has a sufficiency rating of 33.8, according to a March 2005 inspection. The deck and substructure were rated satisfactory, but the superstructure was rated poor.

The scouring, or effect of erosion on the bridge's foundation, was not inspected, according to the federal inventory data.

About 14,000 cars cross the bridge, which was built in 1914, each day, according to 2004 estimates included in the inspection records.

Fort Worth last repaired the bridge in the late 1980s and took X-rays of the entire structure, said George Behmanesh, the city's assistant director of transportation and public works.

"Although the rating is low, that bridge is safe because it is way overdesigned," he said. "It has huge columns. If it were a standard modern bridge, we would be concerned about it."

The Seventh Street bridge over the Trinity and Forest Park Boulevard scored even lower -- 33.2 -- and its deck and substructure were rated fair. Its superstructure received a poor rating, which can include "advanced section loss, deterioration, spalling or scour," federal records show.

An estimated 19,000 cars cross the bridge daily, according to 2004 figures.

Repairs planned

Fort Worth is negotiating with Transportation Department officials to repair the Main Street bridge and replace the Seventh Street bridge, Behmanesh said.

"Both of those bridges were designed and built during a time when they poured an excessive amount of concrete," he said. "There is some erosion and cracks, but because of the size of the columns, we are in good shape. That's what saving our necks."

Behmanesh said the city recently closed a bridge in far north Fort Worth in Denton County. He said the Litsey Road bridge, which crosses Henrietta Creek, was closed because of its poor condition.

"We are willing to close a bridge if we feel it is unsafe," he said.

The Texas 10 bridge over Northeast Loop 820 in Hurst carries more than 11,000 cars daily. It scored 48.8, just below the rating of the Minneapolis bridge.

The inspection data did not include counts for the nine lanes of traffic beneath the Texas 10 bridge -- which, if it collapsed, could cause numerous fatalities and create a rush-hour nightmare comparable to what happened in Minneapolis.

Th Texas 10 bridge, built in 1963, received a poor rating for its deck and a fair rating for its substructure.

Inspection intervals

The Transportation Department hires contractors to inspect bridges at least every 24 months, and that work is supervised by a professional engineer, Cox said. Texas has far more bridges than any other state.

Bridges over bodies of water at least 4 feet deep are also inspected at least once every five years by a specially trained dive team, he said.

In June, state officials announced that they would transfer more than $6 billion from the new-construction fund to the maintenance fund to get more life out of the aging highway system, including bridges.

"The challenge for Texas is that, as our system ages, demand is increasing," agency spokesman Chris Lippincott said.

An outside expert reiterated the state's assertion that Texas bridges are safe.

Most bridges frequented by Texas motorists have redundant support and likely would remain standing even after severe damage.

Therefore, bridges that fare poorly in inspections are probably not a public danger, said Todd Helwig, who is researching ways to strengthen bridges at the University of Texas at Austin.

"I know people are going to be worried whether they should drive across a bridge, but I don't bat an eyelash," he said.

By the numbers

49,829 Number of bridges in Texas as of September.

2 Number of years between bridge inspections; some are evaluated more often.

5 Years between inspections of underwater foundations and columns.

2011 Year by which Texas hopes to have 80 percent of its bridges in good condition or better.

288 Bridges a year that need to be improved to meet the goal.
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