By: Bill Wilson
The nation was seeing signs of an uptick in the economy when the bridge closures began to mount.
It was during a three-month span in late 2009 when the nation’s infrastructure system began to fail in rapid succession. Aside from local media coverage, the string of catastrophic near misses on three bridges was kept from entering the homes of a nationwide audience, even though the message was coming through loud and clear—the bridge system in the U.S. was slowly reaching a fatal state.
In August, the Milwaukee Zoo Interchange had three bridges placed on weight restrictions when inspections revealed stress cracks in the concrete box culverts. A few weeks later, the Lake Champlain Bridge that runs between historic territory in New York and Vermont was closed due to extreme deteriorated conditions. Then in November, the Cline Avenue Bridge in northwest Indiana was shut down indefinitely when corrosion around the piers had reached a debilitating state. One of the Zoo Interchange bridges would close for a week in March 2010 when the Wisconsin DOT (WisDOT) determined it was simply too dangerous to cross.
Three defining moments in an industry that continues to be identified by one tragic collapse—the I-35W Bridge in Minneapolis—three years ago.
Depends on who you ask
According to the latest Federal Highway Administration data (released in December 2009), the number of deficient bridges in the U.S. was actually down from 151,391 in 2008 to 149,647 in 2009. However, the number of bridges in the system increased by almost the same amount—from 601,411 in 2008 to 603,245 in 2009. Structurally deficient bridges decreased slightly (290 less in 2009) while functionally obsolete structures shed an impressive 1,454 off of its list.
The state of Pennsylvania and its Accelerated Bridge Program defined this moment of improvement by taking a nation’s best 629 bridges off of its deficient tally.
“For the first time in more than a decade we saw that upward trend of structurally deficient [bridges] drop,” Pennsylvania DOT spokesperson Rich Kirkpatrick told Roads & Bridges. “The average age of our bridges is 50 years and we lead the nation in the number of bridges aged 70 years or older. That is why it has been always difficult to get ahead of that curve.”
The Accelerated Bridge Program, spearheaded by Gov. Ed Rendell, is the true catalyst behind the improvement. Fueled by an additional $200 million worth of bonds annually, the goal of the program was to have work started or completed on 1,145 structurally deficient bridges by the end of 2010. According to Kirkpatrick, 814 of those structures were under contract when 2009 came to a close.
“We are ahead of the trend right now, and I am pretty confident we can hit the 1,145 by the end of the calendar year,” he said.
The name of the program has little to do with the construction delivery method, although Kirkpatrick said a few were under design-build. It is more about improving the health of the system at a faster rate than the norm. PennDOT also has a stable plan in place to prevent a quick fall into bond debt, using a portion of the motor fuels taxes, called the Bridge Restricted Count, to pay off the annual spike in funds. According to Kirkpatrick, the strategy is basically recession-proof. Despite a decline in gas-tax revenue and the recent action by the FHWA that prohibited tolling on I-80, the state has made the funding for the bridge program the top priority.
If charging were allowed on I-80, Pennsylvania would be looking at an annual transportation budget of $946 million over the next decade. With the FHWA rejection, PennDOT is now scrambling to make up $472 million a year. In mid-April Rendell called the state legislature into special session to figure out a way to fill the hole, if even partially.
Public-private partnerships have been discussed, but would need legislative approval. Kirkpatrick said the state had a $12 billion offer to lease a portion of the Pennsylvania Turnpike but the deal was never considered by the state legislature. A tax on oil company gross profits also may be considered.
With projected revenues coming up short, Pennsylvania roads are the one feeling the neglect. According to Kirkpatrick, 6,000 of the state’s 40,000 miles worth of pavement are in poor condition. Pennsylvania hauled in over $1 billion in stimulus money, with a majority of it going toward road rehab work.
However, if you ask Roads & Bridges readers, the overall condition of the bridge network has not really improved at all. When government officials were asked if the number of functionally obsolete bridges has gone down, gone up or stayed the same over the past year, 64% said there was no change and 25% said the number actually increased. The mood was similar in regards to structurally deficient bridges—51% said the number has stayed the same, while 32% said the number actually worsened.
Money from the American Recovery and Reinvestment Act also has not been a factor in upgrading the nation’s bridge system. When government officials were asked if they were able to address bridge inventory concerns with stimulus money, a hefty 72% said no, and of those bridge managers who actually used ARRA dollars, 58% said it was less than 5% of the state’s total obligation.
Replacing history around the historic
As the Lake Champlain water level dropped in late 2009, Ted Zoli’s confidence level hit rock bottom. Cores of the piers of the Lake Champlain Bridge revealed very low strength and deep cracks in the supports, and an emergency dive inspection dropped the mood yet another notch when divers found the cracking below the water line encircling and running through the entire pier at some locations.
“Now we were in circumstances where we are even more nervous,” Zoli, vice president at HNTB Corp., told Roads & Bridges. Zoli is leading HNTB’s design efforts on a new structure over Lake Champlain.
Further testing showed that every 10°C temperature change created an inch of movement of the piers, which were unreinforced and contained frozen bearings.
Despite the degree of deterioration, which included corrosion in the truss members, crews were still thinking revival over replacement of the Lake Champlain Bridge, which was considered a game-changer when it was built in 1929 because it advanced the use of criss-crossed steel girders from railroad bridges over to highway spans. Structure underpinning and post-tensioned jackets were discussed until the repair cost hit the ceiling.
“I think the combination of an unusual set of circumstances in lake ice and the lack of reinforcement in the piers ultimately led to the bridge’s demise,” said Zoli. “There was pier work done on the bridge in 1945, only 15 years after it was open, so the piers had been a problem right from the beginning.
“To a degree we were fighting a cancer that was not progressing very rapidly, but it had gotten to a point where it needed some major surgery,” he added.
The detour has been difficult on motorists and the DOT pocketbook. A ferry service—costing $30,000 a day—was put in place the day the bridge closed.
Demolishing the structure did not carry any degree of simplicity, either. Because the span connected two lands with history-enriched soil—Indians settled at Chimney Point, Vt., for thousands of years and Fort Crown Point is stationed on the New York side—it was important to build the new bridge in the same alignment as the old one. Also, the lake’s soft bottom required the corroded span to be broken in small enough pieces so cranes could handle the removal after demolition.
“We were worried that if we lost the truss the truss would be buried in the mud and we would never be able to get it out,” said Zoli.
The bridge was taken down on Dec. 28, and at press time the contractor had 80% of the cleanup complete.
The design process involved the public, and HNTB offered two different cable-stayed alternatives, a steel composite version, a concrete segmental box design, a multigirder span and two variations of an arch. Zoli said a modified network tied arch was the clear winner.
“It is important to remember that the environment that the bridge is in, it is so high above the lake it really has a presence in the surrounding areas,” remarked Zoli. “I think that alone gives people a sense of place in the Lake Champlain Valley.”
Two causeways were installed during the demolition process, which will serve as construction areas for the approaches. Zoli said the main span, which will be floated into place, could be erected at a couple of marina locations about a mile or two off the site. That will allow crews to work on the three main sections of the bridge simultaneously, making a fall 2011 deadline reachable. Construction was expected to start the first week of May.
When the 400-ft arch span is ready to be connected, it will probably be transported by a couple of barges. The end floor beams of the arch will be used as part of the lifting apparatus. The tied arch is a basket handle, and the rims will incline toward the center of the deck. The arch rib is actually “eye-shaped,” and a criss-crossing network hanger arrangement will be used. The deck will contain cables—a total of 64, 32 on each side—and floor beams at a 12-ft spacing.
“The cables generally cross more than once,” said Zoli. “They should cross twice in most circumstances.”
Three of the water piers will use floated-in coffer dam-type construction, with the remaining three using conventional coffer dam sheeting, tremie seal-type construction. One spread footing will be on the shoreline and two abutments will be on micro piles to minimize environmental impacts. All of the piers—a total of seven—will be constructed with conventionally reinforced concrete, and drilled shafts 6 ft in diameter will be inserted as deep as 100 ft into rock. A total of six drilled shafts will be used for the main piers and four will be used for the approach piers.
A couple of safeguarding measures—granite and inclined facing—have been designed to protect the piers and foundations from the lake’s punishing ice.
No longer worth the gamble
The Cline Avenue Bridge (S.R. 912) in East Chicago, Ind., became permanently disabled on Nov. 13. That is when the Indiana Department of Transportation (INDOT) closed the structure due to an ongoing case of severe and rapid corrosion. INDOT revealed the following about the extent of the disease:
- Several steel rods holding together the individual bridge sections had failed completely due to corrosion, and other tension rods were deteriorating rapidly due to accelerated corrosion;
- Corrosion was occurring inside the walls of the concrete girders below the bridge deck, and those girders were cracking;
- New cracks were developing on an accelerated basis. Over 300 new cracks were discovered during the bridge’s last inspection; and
- Cracks were developing along cantilevered sections of the bridge and on the bridge columns.
As recently as spring 2009, pier 7 of the Cline Avenue Bridge required emergency repairs and temporary structural steel support.
More extensive rehab was conducted a few months earlier, in December 2008, after the upper portions of concrete piers supporting the elevated roadway, which carries six lanes of traffic and two shoulders, had suffered significant corrosion, and INDOT engineers concluded that the top 10 ft of the damaged piers would have to be removed and replaced.
Removing the tops of the piers required temporary support for the three concrete box girders carrying the roadway. Contractor JCI Bridge Group erected a dozen temporary steel piers in clusters of four, braced and tied together, under each of the three box girders.
“The piers were fabricated from 30-in.-diam., 7?8-in.-wall steel pipe, filled with sand” said Carl Tungate, P.E., of JCI. “The 54-ft-tall piers sat on sill beams on the old footers.”
The weight of the bridge superstructure was transferred to the temporary piers so crews could make the necessary repairs. JCI used 48 200-ton Enerpac jacks to lift the bridge a half-inch off the old piers with no interruption to traffic flow.
So when the bridge showed signs of breaking down again in November 2009, INDOT knew it had exhausted all repair options and ultimately decided to close the span indefinitely. Originally INDOT was going to go through with a $90.6 million plan to replace the superstructure, but it was scratched in search of a better alternative.
The Cline Avenue Bridge was a blue-collar carrier, connecting steel mills, casinos and the cities of East Chicago, Hammond and Gary to the Indiana Toll Road. The infrastructure omission created an uproar from local businesses, and INDOT quickly implemented a short-term fix that included the installation of 80 signs and improved signal operation at eight intersections to help move the sudden swell in traffic on local roads. INDOT also contracted with Wilbur Smith Associates to examine traffic pattern changes since the closure and to make recommendations for additional improvements.
At press time, INDOT was currently reviewing public comments collected over two months in search of a long-term solution.
As a result of Cline Avenue’s ongoing troubles INDOT launched a six-year, three-phase inspection contract dealing with similar concrete box girders around the state. The work involves visual inspections of the interior and exterior surfaces of the web walls as well as the top and bottom slabs. It also includes bridge deck cores to check for chloride penetration, testing the grout and inspecting for corrosion in some of the box girders. The second phase of this inspection was expected to continue through March 2010.
Taking a load off
In Wisconsin, nothing carries more moving steel than Milwaukee’s Zoo Interchange. More than 345,000 vehicles a day tread rubber over the complex concrete network, but in August 2009 the interchange was losing some serious muscle mass. Three structures, also of the concrete-box variety, had fallen victim to cracking in the concrete girders that rest on vertical supports, and in some locations the concrete had broken away from steel reinforcing bars.
It was time to lighten the load, so WisDOT decided to implement weight restrictions on the damaged bridges. The northbound bridge through the Zoo Interchange, which carries U.S. 45 over eastbound I-94, was posted with a 30-ton weight restriction; the bridge that carries southbound U.S. 45 to the eastbound I-94 bridge was set at 35 tons; and the bridge that carries northbound U.S. 45 to the westbound I-94 bridge was marked at 40 tons.
“We had some inspection reports in the summer of 2009 that were showing some deterioration of the three structures,” Ryan Luck, southeast freeways construction director for WisDOT, told Roads & Bridges. “We did an additional thorough inspection of those bridges, and after that review came to the conclusion that we needed to post those three bridges at reduced weights.”
Enforcing the modified loads, however, quickly spun out of control—even with the help of weigh-in-motion sensors. According to Luck, one in six trucks coming northbound on U.S. 45 were in violation “We were seeing 200 violators a day.”
So another inspection on the U.S. 45 northbound bridge was carried out, and additional cracking was discovered. On March 26, officials decided to close the structure.
Fortunately, crews had been working on the replacements since late 2009, and thanks to a fast-track steel fabrication schedule, the U.S. 45 northbound bridge was only days away from its 8-in.-thick concrete deck pour. The pour was moved up to noon on March 27, and the bridge was back open to traffic a week later.
“The story of how we began last fall and worked very hard to get the steel procured and overcame all of the milestones, that put us in the position to be successful here,” said Luck.
Milwaukee Constructors, a joint venture comprised of Edward Kraemer & Sons Inc., Lunda Construction Co. and Zenith Tech Inc., the same trio that built the Marquette Interchange nearby, decided to execute an alternative alignment concept, which allowed crews to construct the new bridges right alongside the existing ones. The maneuver still proved to be difficult due to the tight surroundings and time of season. Fortunately a mild winter allowed crews to install steel H piles and pour the concrete foundations and piers (4,000 psi strength, five- to seven-day cure time) in time for a March 1 steel delivery. Grade 50 steel I girders are being used, and the switch from concrete girders has opened up some short vertical clearances in the interchange and has reduced some of the span lengths.
Traffic is expected to be allowed on all three new alignments by May 24, and the existing structures will be demolished by June 15.
