Bridge Collapse Spurs Concern

By Hol Wagner | September 28, 2010

In the wake of the disastrous and totally unexpected collapse of a large section of the Interstate 35W bridge over the Mississippi River in Minneapolis on Aug. 1, fears have been raised across the country about the safety of bridges, and reassurances have generally been forthcoming. But everyone involved in any way with the highways and bridges of this country knows that sufficient funding is simply not available to properly maintain, and replace if necessary, this aging infrastructure. If there can be a positive result of this tragedy, it will be the heightened attention focused on the need to adequately fund the upkeep of our infrastructure.

The two national associations most closely involved with highway and bridge construction and upkeep both used the incident to appeal for increased emphasis on the nation's crumbling infrastructure.

"We are deeply saddened for all those affected by the tragedy in Minneapolis that has touched so many people," said Stephen E. Sandherr, chief executive officer of the Associated General Contractors of America.

"While we await answers on the cause of this tragedy, we should unite in our efforts to strengthen the nation's stressed infrastructure," said Sandherr. "Americans should be able to rely on our highways, roads and bridges every day, knowing their safety is the number one priority."

Pete Ruane, president and CEO of the American Road & Transportation Builders Association, also responded, "Bridges can be rebuilt and roadways repaired, but lives touched by tragedy can never be wholly repaired. On behalf of the 5,000 public and private sector members of the American Road & Transportation Builders Association, we express deep sadness and offer our prayers to those families who lost loved ones or were injured.

"We also commend those first responders and road workers who took heroic action immediately following the collapse to help rescue the victims, and those public safety officials currently conducting the recovery operations.

"Our transportation systems are an integral part of the American way of life. We are united in our grief, steadfast in our commitment to assess the cause and implications of this accident, and dedicated to the goal of ensuring the safety of the American motoring public."

ARTBA then provided some information that is probably not reassuring to the motoring public, noting that of the 594,709 bridges in the United States under the purview of the Federal Highway Administration, fully 152,945, or 26 percent, are structurally deficient or functionally obsolete, according to 2006 data from the FHWA. The association then furnished the definitions of those two descriptions, which have caused so much anxiety among motorists. The U.S. Department of Transportation, ARTBA explained, defines structurally deficient as meaning that "significant load-carrying elements of the bridge are found to be in poor or worse condition due to deterioration and/or damage, or the adequacy of the waterway opening provided by the bridge is determined to be extremely insufficient to the point of causing intolerable traffic interruptions. A deficient bridge, when left open to traffic, typically requires significant maintenance and repair to remain in service."

As for functionally obsolete, ARTBA explained, such bridges result from changes in traffic demand on the structure. For example, a bridge designed in the 1930s would have shoulder widths in conformance with design standards of that era. Design standards have since changed, and the difference between the current required shoulder width and the 1930s standard represents a deficiency.

The FHWA itself quickly moved to reassure motorists that most bridges are indeed safe and the agency's comprehensive bridge inspection program is designed to discover defects before the bridges become dangerous. To put the public more at ease, the agency then asked all states to redouble their bridge inspection efforts, review their inspection programs and immediately inspect any bridges thought to be potentially unsafe. Emphasis was placed on bridges of the same design as the failed Minnesota bridge: those of the steel deck truss type, with the roadway on a deck atop the truss structure rather than passing through at the bottom of the truss.

Individual states varied in their reactions, and a sampling of those in Mountain America follows.


Gov. Janet Napolitano ordered a close review of the state's 7,335 bridges. She specifically ordered the Arizona Department of Transportation to concentrate on high-traffic spans in the state's four major urban areas. An aide to the governor said ADOT officials have promised to make it a priority to inspect three steel bridges that are built to the same design as the eight-lane structure that failed in Minnesota.

Officials have identified those bridges as the structure over the Gila River on US-191, a span over the Little Colorado River on US-89 near Cameron, and another bridge on US-89 between Chino Valley and Paulden over Hells Canyon. But ADOT representative Doug Nintzel said nothing in the governor's order means engineers from her agency will actually physically inspect those three spans — or even any of the other 4,717 in the state highway system. Instead, she said the engineers would review the records of prior inspections, done at least once every two years. Only if there is reason to question the safety would teams go out and look at a structure.

Nintzel said two of those three spans have undergone inspections within the past year. The US-191 bridge is due to be replaced as part of a highway project starting this fall. He added that under the governor's order, the agency's engineers will review the records of prior inspections, done at least every two years, before deciding which of the state's 4,717 highway bridges will receive an additional hands-on inspection. ADOT expects to conduct additional on-site inspections once the records review is completed.

State engineers also will help county officials review the records of two bridges also with steel deck truss construction: one in Mohave County over Sand Hollow Wash and an Apache County bridge over Querino Canyon.

Nintzel also acknowledged that there are 42 bridges in the state highway system classified by the U.S. Department of Transportation as structurally deficient. "It doesn't mean the bridge is unsafe and shouldn't be driven on. It tells our engineers that those are priority bridges that will need to be repaired or replaced."

Additionally, ADOT executive director Victor Mendez issued a statement to the media that said, in part, "Arizonans can have confidence in the condition of our bridges. Arizona's bridges have annually rated among the best in the nation. The Federal Highway Administration's latest ratings show Arizona and Nevada are the leading states in bridge ratings. And the American Society of Civil Engineers gives Arizona an overall grade of A- for highway bridge safety.

"Key reasons for Arizona's strong ratings include our dry climate, the relatively young age of many structures and modern engineering design associated with our bridges. Many of these bridges have been built as part of the Valley's freeway-construction program."

He went on to explain, "There are 4,720 interstate and state highway bridges in Arizona. There are no bridges on the state highway system that have major deficiencies.

"Less than 1 percent of ADOT bridges are listed as 'structurally deficient,' which means they need some type of repair. Repairs are prioritized, and all these bridges have either been repaired, are being repaired or will be repaired in the next few years.

"Let me assure you that if ADOT determined a bridge to be unsafe, the bridge would be closed immediately until repairs were completed."


Colorado has 3,757 state-owned bridges and more than 4,790 bridges owned by cities and counties. Of the state-owned spans, 110 are considered in need of replacement and another 375 are in need of rehabilitation, said Colorado Department of Transportation spokesperson Stacey Stegman. She said the department spends about $30 million of its $1-billion budget a year on bridge repair and replacement.

Speaking of the Minnesota bridge collapse, Doug Aden, chairman of the Colorado Transportation Commission, said it is unclear what caused the bridge in Minneapolis to collapse, so it is premature to say whether something similar could happen here.

"I don't think it would happen in Colorado," Aden said. "We do have — which we've acknowledged for a long time — a backlog of bridges that need to be replaced, and we're working on that as funds allow."

State transportation officials estimate the backlog at $758 million, a figure that does not include larger projects such as the I-70 viaduct across Denver's Globeville area, which alone carries a replacement tag of up to $700 million.

Mark Leonard, state bridge engineer for CDOT, said there are six steel deck truss structures in Colorado, and all of them will be inspected. Two are in the state highway system, while four are on county roads or city streets. CDOT will work with city and county officials to inspect those structures. The six Colorado bridges are:

  • On Colorado 120 over the Arkansas River, milepost 3.696 west of Penrose.
  • On US-24 over the Arkansas River, milepost 213.434 near Buena Vista.
  • In Mineral County, on County Road Marsh Parkway
  • In Pueblo County, on County Road 273.
  • In Pueblo, on Union Avenue.
  • In Red Cliff, on Water Street.

Denver's Rocky Mountain News had the right idea when it editorialized on August 3: "Bridges collapsing for no immediately apparent reason are extremely rare.

"Less rare are collapses with a proximate cause. This spring, an off-ramp of a San Francisco bridge collapsed after it was weakened by a burning gasoline-tank truck. In 2002, 14 people were killed when a barge plowed into a bridge in Oklahoma. In 1980, 35 died when a ship rammed a bridge over Florida's Tampa Bay.

"But unique, discrete collapses almost never happen. A notable instance was the collapse in 1980 of the Silver Bridge over the Ohio River with the loss of 46. But the statistical improbability of people suffering the same fate as the motorists caught up in Wednesday's collapse of the Interstate 35W Bridge in Minneapolis is of little comfort when faced with the daily task of getting from one side of the river to the other.

"Now engineers must determine why the Interstate bridge failed. It had been built to federal standards, was inspected regularly and was thought to have several years of use left. But it had been identified as 'structurally deficient' and may have succumbed to metal fatigue.

"Washington was immediately importuned to do something, anything. But after the rescue and recovery operations, the first order of business is to confirm why a bridge undergoing routine use on an ordinary summer day fell without warning. Everything else proceeds from learning that cause."


In arid Nevada, the Department of Transportation simply issued a press release in a attempt to assuage public fear of collapsing bridges, and reading in part, "Following the tragic collapse of Minnesota's I-35W bridge, the Nevada Department of Transportation joins the nation in extending sympathies to all those affected, and will continue an aggressive bridge inspection and rehabilitation program that has led Nevada bridges to be named the nation's best.

"'We extend our heartfelt sympathy to all of those affected by the tragic Minnesota bridge collapse, and I have personally been in contact with the Minnesota Department of Transportation to offer any services that may be needed,' NDOT Director Susan Martinovich said. 'In Nevada, as throughout the nation, safety is our primary focus. The Nevada Department of Transportation will continue the extensive bridge program that has led our bridges to be named the nation's best.'

"The Nevada Department of Transportation inspects all bridges in the state of Nevada, including city and county-maintained structures, and spent $24.3 million for bridge rehabilitation, replacement and seismic retrofitting during fiscal years 2005 and 2006. All bridge structures are inspected every two years, while bridges with more extensive deterioration are inspected more often.

"'Bridges showing any type of issues with structural integrity are prioritized first for rehabilitation,' NDOT Chief Bridge Engineer Mark Elicegui said.

"In late 2006, Nevada was recognized as having the nation's top bridges by a Better Roads magazine survey [which parroted FHWA data]. Ranking bridge conditions through October 2006, the survey shows only 4 percent of Nevada's approximately 1,800 state, county and city bridges being functionally obsolete or structurally deficient, compared to a national average of 25 percent. Arizona came in second with the only other single-digit rating at 5 percent. ...

"Nevada has close to 1,800 bridges. Approximately 1,050 of those bridges are under the direct responsibility of NDOT, with the remainder being under the jurisdiction of local governments. During fiscal years 2005 and 2006, NDOT spent $24.3 million for bridge rehabilitation, replacement and seismic retrofitting.

"The Nevada Department of Transportation has an aggressive bridge inspection and maintenance program. All NDOT and consultant bridge inspectors are trained to federal standards. These professional inspectors thoroughly review all elements of each bridge to evaluate condition, and assign ratings to the bridge deck, superstructure and supporting substructure elements. Minor bridge repairs are often performed immediately during bridge inspection in order to avoid any delays that could allow deterioration to worsen.

"To preserve Nevada's public bridges in good condition, the Nevada Department of Transportation prioritizes any necessary bridge repairs in the following order: 1) Replace or rehabilitate structurally deficient bridges before they become hazardous or overly burdensome to users. 2) Replace or rehabilitate functionally obsolete bridges before they become hazardous or overly burdensome to users. 3) Seismically retrofit bridges that do not meet current seismic standards. 4) Apply timely repairs to existing structures.

"Nevada has the lowest percentage of bridges of any state categorized as structurally deficient or functionally obsolete. Approximately 70 Nevada bridges (nearly 4 percent of all Nevada bridges) qualify for federal funding as structurally deficient or functionally obsolete bridges. ...

"Minnesota's I-35W bridge was a deck-truss bridge structure. Nevada has only one deck-truss bridge structure, located on US-93 over Meadow Valley Wash in Caliente. This structure has four truss lines, providing additional redundancy and support, while the structure that failed in Minnesota had two truss lines."

New Mexico

As in most states, New Mexico's governor stepped in to stem the growing concern over local bridge safety. In an Aug. 2 statement, Gov. Bill Richardson said, "Today, I have directed our bridge inspection teams to immediately review the safety of four steel-truss bridges in New Mexico that have a similar construction to the bridge in Minneapolis.

"We have an exhaustive bridge inspection program in New Mexico that identifies bridges in need of repairs or replacement every two years. When necessary, we conduct additional inspections and take action on bridges identified as deficient," Gov. Richardson said. "In light of the bridge collapse in Minneapolis, I'm ordering the Department of Transportation to take proactive steps to ensure our bridges are safe."

The four steel deck truss bridges include:

  • I-25 near Nogales Canyon (northbound and southbound)
  • US-64 Gorge Bridge near Taos
  • US-54 near Logan on the Canadian River
  • US-64 near Shiprock

"On behalf of the people of New Mexico, let me also express my deepest condolences to the family and friends of the victims of the tragic bridge collapse in Minnesota," said the governor. "As always, the state of New Mexico stands ready to offer any assistance the state of Minnesota may require."

"I want to assure all New Mexicans that our bridges are safe," Transportation Secretary Rhonda Faught said. "If we have even a slightest of doubts on the structural integrity of a bridge, we conduct a thorough inspection to ensure we do not endanger public safety. If we determine a bridge is not safe, we either post weight restrictions or we shut it down."

In Las Cruces, the Sun-News reported that New Mexico State University engineering professors would be aiding in the inspection of the steel deck truss bridges: "New Mexico State University engineering professors who specialize in bridge safety research have been asked to inspect bridges in the state that are similar to the one that collapsed Wednesday in Minneapolis. Ken White, who heads the department of civil and geological engineering at the university, said he received an e-mailed request Thursday [Aug. 2] to examine New Mexico's steel-truss bridges."

The news report continued, "The bridges rely on steel, horizontal supports called trusses — a similar construction as the Minneapolis bridge. White said truss bridges, because of their design, are more susceptible to collapse than other types of bridges. However, he said it's rare for them to fail because of a structural flaw, as happened [August 1].

"New Mexico Department of Transportation spokesman S.U. Mahesh said NMSU experts have been asked to review the bridges because the department has a bridge inspection contract with the university. He emphasized that the public shouldn't be alarmed by the measure.

"'We're not saying any of these bridges are not safe,' he said. 'These are safe bridges. This is a precautionary measure to ensure we haven't missed anything.'"


In Utah, a substantial number of bridge inspections were being reviewed, the Deseret News reporting on Aug. 2, "Gov. Jon Huntsman Jr. today asked the Utah Department of Transportation to begin a review of about 200 Utah bridges that pose risks or that are heavily used, in the wake of a bridge collapse in Minneapolis . . .

"The Utah review will begin immediately, Huntsman said in a statement. An outside contractor will verify all the data collected.

"'The well-being of Utah is my top priority,' he said. 'I hope all citizens will feel confident that the roads and bridges in Utah are safe for travel and well-maintained.'

"Every two years, UDOT does an inspection of the state's 2,700 bridges. The governor's review will focus on about 200 bridges that have high traffic, as well as those that cross over rivers or high mountain passes."

The next day, the same newspaper added, "While the cause of the Minneapolis accident is unknown, Utah engineers say residents shouldn't worry. A structurally deficient bridge doesn't mean it's on the brink of catastrophic failure, and the Minneapolis bridge had a design that's more vulnerable than most Utah bridges.

"'It's like having the roof leak, but the house isn't falling down,' said David Eixenberger, bridge operations engineer for the Utah Department of Transportation. 'It does not mean that it's unsafe or not fit for use.'

"In total, UDOT monitors about 2,700 bridges statewide. Of those bridges, about 1,800 are state-owned bridges and about 900 are owned by local entities. Eixenberger said roughly 10 percent to 15 percent of the local bridges could be considered structurally deficient, while about 2 percent to 3 percent of the state bridges were ranked deficient. About 13 percent of the nation's nearly 600,000 bridges are structurally deficient, according to the Federal Highway Administration."

On Aug. 7 the Salt Lake Tribune updated, "David Eixenberger, Utah Department of Transportation's bridge operations engineer, said he expects money for the inspections to come from the agency's existing budget. The state typically spends about $900,000 a year on bridge inspections.

"'These are things we would normally be doing, but we are doing these on a much quicker rate,' Eixenberger said.

"Eixenberger said the inspections will happen in two phases, with the first finishing by September.

"That first phase will focus on bridges such as along Interstate 80 from State Street to Highland Drive, and the bridge at Beck Street in Davis County. The second phase will focus on bridges with fewer areas that can hold a load if some part of the bridge structure were to fail.

"Second-phase inspections are anticipated to be complete by November, after which UDOT will issue a report.

"'We feel the bridge system is healthy,' Eixenberger said. 'While it's not perfect, we feel it's healthy and safe overall.'"


Finally, in Wyoming the issue was the same: reassuring the traveling public that bridges are not going to collapse beneath them. On Aug. 7 the Wyoming Department of Transportation issued a release similar to those of other states: "The recent Interstate 35W bridge tragedy in Minneapolis placed a new focus on the issue of bridge safety across the United States and raised questions about what can be done. Safety is a chief priority for WYDOT. Every bridge in the state is inspected at least once every two years, and more frequently if necessary.

"The inspections measure and record dimensions, clearances, alignments, waterway data and structural condition. The structural condition is evaluated using structural elements such as girders, decks, railings, columns and pilings. Each element is evaluated based on several condition state assessments. WYDOT tracks the status of 2,774 bridges utilizing a bridge management system. Of that total 1,929 of the bridges are owned and maintained by WYDOT, and 845 are under the jurisdiction of municipalities and counties.

"'Our inspections are based on a variety of factors which may result in a bridge being rated as structurally deficient or functionally obsolete, but that does not mean that bridge is unsafe. It just means it may need repair or possibly replacement,' Keith Fulton, assistant state bridge engineer for WYDOT, said.

"Among the WYDOT-owned bridges, 1,838 (95 percent of the total) are classified as 'acceptable,' with the remaining 91 being structurally deficient or functionally obsolete. [A complete online listing was offered.] Among city- and county-owned bridges, 597 (71 percent)are acceptable and 248 are structurally deficient or functionally obsolete.

"When WYDOT-owned and locally owned bridges are combined, 88 percent of the 2,774 bridges statewide are classified as acceptable, and 339, or 12 percent, are structurally deficient or functionally obsolete.

"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 unsafe or likely to collapse. If inspectors find unsafe conditions they will restrict access or close the bridge.

"Structural deficiency or functional obsolescence are classifications used to determine eligibility for federal bridge funds rather than an indication of safety, and are determined by the Federal Highway Administration (FHWA).

"Structural deficiency is determined by an assessment of physical condition and load ratings. Physical condition assessments are made by inspectors who look for deterioration of bridge elements which include the deck, girders and supporting columns. Deterioration could include rusting of steel components, cracking of concrete, or something as simple as peeling paint.

"Load ratings refer to how much weight the bridge can carry on a repeated basis, without damaging the bridge.

"Functional obsolescence is judged by how well the bridge meets current and anticipated traffic volumes and types.

"In the aftermath of the Minneapolis bridge collapse, U.S. Secretary of Transportation Mary Peters called on states to immediately inspect any bridges of a similar design to the one that collapsed in Minneapolis.

"'Even though we don't know what caused this collapse, we want states to immediately and thoroughly examine all similar spans out of an abundance of caution,' Peters said.

"The FHWA lists 756 'steel deck truss' bridges in the country. Just two are in Wyoming: I-25 service road over the South Fork of the Powder River south of Kaycee; Fremont County Road No. 298 over the Wyoming Canal near Diversion Dam Junction about 40 miles northwest of Riverton.

"Those bridges, along with a third similar structure, the US-26/89 bridge over the Snake River at Hoback Junction south of Jackson, will be inspected by mid-August."

Prompt Action

Finally, and moving quickly while the opportunity and focus were there, House Transportation and Infrastructure Committee Chairman Jim Oberstar (D-Minn.) offered an initiative in Congress on Aug. 8 to quickly address America's bridge problem.

ARTBA's Pete Ruane responded: "Chairman Jim Oberstar today displayed the political leadership and 'can do' attitude that are key to beginning the hard task of seriously addressing America's national transportation system deficiencies.

"The federal surface transportation investment program needs to change to meet the demands and challenges of this century, not the last one. We believe the Oberstar bridge proposal signals a necessary first step toward legislatively refocusing and reinvigorating it.

"The approach he has outlined is not Washington 'business as usual.' It is a strategic, targeted capital investment plan that has accountability and a defined national outcome — eliminating structurally deficient bridges on America's most heavily traveled highways. He is proposing a 'surgical strike' approach that could be a model for the future.

"The American Road & Transportation Builders Association supports and applauds Chairman Oberstar's initiative."

Associated General Contractors of America similarly announced its support for Oberstar's "National Highway Bridge Reconstruction Initiative," which would provide dedicated funding to states to repair, rehabilitate and replace structurally deficient bridges on the National Highway System.

"We applaud Chairman Oberstar for his prompt action to improve public safety and public confidence in the stability of our nation's bridges," said AGC CEO Stephen E. Sandherr.

The initiative, which is expected to be introduced in the House when Congress returns in September, has four main components:

  • Significantly Improves Bridge Inspection Requirements. Requires the Federal Highway Administration (FHWA) and states to significantly improve the processes for inspection of structurally deficient bridges.
  • Provides Dedicated Funding. Provides dedicated funding to repair, rehabilitate and replace structurally deficient bridges on the NHS.
  • Distributes Funds based on Public Safety and Need. Requires the U.S. Department of Transportation to develop an administrative formula for distributing all funds. Prohibits any Congressional or Administration earmarks.
  • Establishes NHS Bridge Reconstruction Trust Fund. Establishes an NHS Bridge Reconstruction Trust Fund, modeled after the Highway Trust Fund, to finance the repair, rehabilitation and replacement of structurally deficient NHS bridges.

The sources and amount of dedicated revenue will be determined after FHWA and the states provide additional data on the costs to finance the repair, rehabilitation and replacement of structurally deficient NHS bridges.


Bridge Girders Fall In Arizona

Mesa, Ariz. — Even as recovery efforts were still under way at the site of the I-35W bridge collapse in Minneapolis, concrete girders of a bridge under construction on the Red Mountain Freeway in Mesa fell unexpectedly to the ground as work was under way on Aug. 9. No one was hurt in the incident.

Pulice Construction, the general contractor for the Loop 202 construction project between Power Road and University Drive, is conducting an investigation in coordination with the Arizona Department of Transportation on the cause of the incident that occurred along the Red Mountain Freeway (Loop 202), just east of Power Road.

Nine of 11 girders in a 114-foot-long section of a future bridge fell from their pier caps at approximately 8:30 a.m. The girders had been placed atop the pier caps three weeks earlier and were ready to be braced with concrete. Parts of the girders fell into a nearby canal operated by the Central Arizona Project.

Once complete, the structure will be redundant, meaning multiple girders will support it. Redundant bridges have been shown to be consistently stable, even if one or more girders are damaged.

As with all ADOT projects, officials will conduct a rigorous inspection of the bridge before approving it. The incident will not affect the completion date of this final segment of the Loop 202, which is expected to open in late summer 2008.