Mississippi River Bridge: A New Element to St. Louis

Wed March 24, 2010 - Midwest Edition
Kathie Sutin


Photo Courtesy of Mississippi River Bridge Team. Artist’s rendition of the new 1,500 ft.,(457 m) cable-stayed bridge across the Mississippi in St. Louis, which will bring much needed traffic congestion relief to commuters.
Photo Courtesy of Mississippi River Bridge Team. Artist’s rendition of the new 1,500 ft.,(457 m) cable-stayed bridge across the Mississippi in St. Louis, which will bring much needed traffic congestion relief to commuters.

The Missouri Department of Transportation (MoDOT) and Massman-Traylor-Alberici (MTA), its joint venture contractor, will break ground on a new $667 million Mississippi River bridge in St. Louis later this month.

The event will mark the beginning of the long-awaited new bridge across the country’s longest river. With towers 400 ft. (122 m) tall—two-thirds the height of the Arch—the bridge will add a striking new element to the St. Louis skyline.

The bridge, with a main span of 1,500 ft., will be the third longest cable-stayed bridge in the country. In addition, it will be the first in the nation constructed under new American Association of State Highway and Transportation Officials (AASHTO) regulations on Load and Resistance Factor Design (LRFD) bridge design specifications.

Key components of the project include:

• A new four-lane bridge one mi. north of the existing Martin Luther King Bridge

• A Missouri North I-70 interchange between the existing I-70 and the new bridge, with further connections to the local street system at Cass Avenue

• An Illinois I-70 connection between the existing I-55/64/70 tri-level interchange and the main span

• Improvements at the I-55/64/70 Tri-Level Interchange in East St. Louis, Ill., which will connect to the I-70 connection leading to the main span.

Estimated at $346 million the bridge and its Missouri and Illinois approaches will take the lion’s share of the construction cost. The Missouri North I-70 interchange will cost an estimated $57 million and the tri-level Illinois relocated I-70 roadways will cost $264 million. Of the $667 million construction costs, the federal government will provide $239 million, the state of Illinois, $313 million and the state of Missouri, $115 million.

MTA is a joint venture between Massman Construction Co., headquartered in Kansas City, Mo. with regional offices in St. Louis; Traylor Bros. Inc. headquartered in Evansville, Ind. and Alberici Constructors Inc. of St. Louis. Expected completion date is January 2014.

“MoDOT is still reviewing bids on the Missouri approach. Illinois has awarded a number of contracts for its approaches and some demo work is already underway,” said Andrew Gates, a MoDOT representative.

The four-lane bridge is the first part of an “Ultimate Project Concept” that includes eventually building a “companion bridge” next to the new one when eight lanes are needed and funding is fund. The total cost of the Ultimate Project Concept is between $1.8 and $2.2 billion.

A Long Time Coming

For years “folks were saying, ’We’ve got a problem’” with traffic coming into St. Louis from the Poplar Street Bridge, Gates said. In 1990 regional leaders began discussion on construction of a new bridge linking downtown St. Louis with Illinois, according to Gates. They spent the next several years studying the problem, looking at options and finally picking a solution they thought best. By 2001 area leaders had an environmental impact statement approving the location and the process and the situation became, “If you can get the money, you can begin working on it,” he said.

By 2005 inflation pushed the cost to $2 billion. “Neither Illinois nor Missouri could really afford that grand a project,” Gates said.

“So we went to work trying to figure out how we could reduce the cost and how we could fund what we can build,” stated Greg Horn, MoDOT’s project director for the bridge. “Really the cost drove the bridge, and that’s how we ended up with the cable-stayed [design].

“By the time we got our go-ahead from the federal government we had a $2 billion project and the times had changed,” Horn said. “Back in the 1990s mega projects were funded through the federal government a lot more commonly, which was no longer the case.” By the 2000s, the federal government was no longer funding mega projects.

Alternatives for funding

Over the next few years, Missouri and Illinois discussed ways they might be able to finance construction of the bridge.

One concept was to build it as a private-public partnership, charging a toll for use and construction of a “coupler bridge” with the existing Martin Luther King Bridge.

Illinois fought the toll bridge idea since many residents of the east side of the river travel to St. Louis daily to work.

Eventually the two states agreed to construct two bridges a mi. north of the existing King bridge — one now and one sometime in the future. One bridge will carry eastbound traffic while the other westbound traffic. Until there is funding for the second bridge, one four-lane bridge will be built carrying traffic in both directions. The governor of each state signed the agreement in Feb. 2008.

“The big story is the original was going to be two side-by-side bridges totaling eight lanes,” Horn said. “We’re just building one of those bridges now.”

The design by the architecture and engineering consulting firm HNTB calls for two lanes in each direction with enough shoulder that can be re-striped to three in each direction. MoDOT traffic analysis project the bridge can handle traffic for the next 20 to 30 years, Horn said. “At least that is what our analysis shows right now,” he added.

Meeting with the Coast Guard, planners learned they needed a minimum span of 1,500 ft., which is the distance between the piers in the river.

“When you look at what kind of economical bridge can span 1,500 feet it turns out to be our original choice of cable-stayed bridge,” Horn commented. “We are fortunate that the most economical bridge is a cable stayed, which is also a beautiful bridge so we have accomplished two things at once.”

Traffic Demands Another Bridge

“There is no question that the new bridge is needed,” Gates said. The three downtown bridges — the Poplar Street Bridge, the King Bridge and the historic Eads Bridge — plus the McKinley Bridge about a mi. north of the downtown area cannot handle the volume of traffic it currently has according to officials.

“Basically the problem is the Poplar Street Bridge has three Interstates on it. That is the simplest way of stating the problem,” Gates said. “There are only two bridges in the U. S. that cross a major river that have three Interstates on them. All that traffic into downtown St. Louis creates a choke point,” he said.

Also significant is the age of the Poplar Street Bridge, the major bridge across the Mississippi in St. Louis, Gates said. “The Poplar Street Bridge is pushing 40 and ready for some work. However, doing maintenance work without a way to relieve some traffic would be a nightmare,” Gates stated.

“Removing one of the three Interstates off the Poplar Street Bridge onto the new bridge, will provide needed traffic capacity for the region, improve travel times, hopefully increase economic growth and, of course, reduce crashes because of the reduced congestion on the Poplar Street Bridge,” he said.

Unique Challenges

Constructing a new bridge over the country’s largest river will not be easy. “You’ve got some real challenges working with a river like the Mississippi,” Horn said. Two he mentions immediately are floods and earthquakes. This bridge will be heavier than a similar bridge in Greenville, Miss.

“It requires more reinforcement steel because of some of the issues with earthquakes,” he said. “And this is the first bridge built under the new AASHTO standards, and the new standards require more reinforcement steel inside the concrete. And there is a lot of steel in this bridge,” commented Horn.

The earthquake threat means more work to make sure the piers are drilled deeper into bedrock. “The footings are deeper. You have about 20 feet. of water, you have about 50 feet. of mud and silt and then you go further into bedrock below that. They have more reinforcement steel in the bridge structure and within the concrete. There are a whole lot of structural details that have to be done to meet the standards.”

Another Factor — River and Barge Traffic.

“In this location there is a lot of barge traffic for the contractor to deal with compared to some other bridges, like the bridge in Greenville that is a very similar type of bridge or even Cape Girardeau, Mo.,” Horn said. “You have a levy on the Illinois side and a flood wall on the Missouri side, so you have limited access that makes it very difficult to built those back spans.”

The contractor will “only get so many windows” to build between barge traffic, he said. “He has to basically shut down the river to put some pieces up, so he has to work with the Coast Guard and get permits.”

In addition, it does not get any easier when two states are involved in the project. “This bridge is a little more difficult because it’s between two states so the contractor has to abide by Illinois and Missouri Department of Natural Resources requirements,” Horn said. “They have to get permission from both states and different governmental agencies. There are labor unions on both sides, making it more difficult to build because each has its own rules and regulations that need to be negotiated. A lot of things make this bridge more difficult than a typical bridge.”

Some challenges are related to the construction of the bridge itself, Mark Schnoebelen, vice president of Massman, said. “Cable-stayed bridges in and of themselves are fairly risky structures because at some point you have almost 750 feet of bridge deck cantilevered off of towers that’s only supported in the center so it’s kind of like a fulcrum or a teeter-totter type arrangement. There is a lot of risk involved in that. If a tornado would decide to blow through town about the time you have the deck cantilevered, that could be a problem.”

With a limited staging area, much of the work will be done from barges, again presenting other challenges, Schnoebelen said. “You’re working from floating barges, a floating plant, so you’re not working on a stable surface and the river fluctuates,” he said. “It gets extremely high and it can go extremely low and that can be difficult to cope with. Then there are floods and ice flows to deal with, not to mention everyday barge traffic. It is a heavily traveled stretch of the river. Some very big tows will be going through the middle of our construction project.” This will mean coordination, not only with the Coast Guard, but also with the towing industry, the boat operators themselves and the Corps. of Engineers.

The 400-ft. tall towers will present another challenge. “In fact, the towers are so tall they become an issue for the FAA and surrounding airports,” Schnoebelen said. With Parks Airport just across the river in Illinois, the towers will have to be marked for air traffic, he added.

“Now you have issues with wind,” Horn said. “They’ll have these huge cranes out there. Something that most people don’t think about is there are going to be some days they’re shut down because they can’t use these cranes because of the wind 400 feet up in the air.”

The construction schedule is also daunting. “It’s in an extremely tight schedule,” Schnoebelen said. “It’s a very large bridge to be constructed in a relatively short period of time. Anytime you’re working in the Mississippi River, that’s a challenge.”

The foundations for the bridge are particularly large and difficult to construct because of “just the sheer size of it” and their depth, he said. “The shafts are very large —they’re 11-and-a-half feet diameter drilled shafts — the largest shaft ever constructed in Missouri or even the surrounding states,” he said. “The towers are extremely tall so you need a form system that is easy to maneuver at great heights. The piers, roughly 100 feet below the water’s surface, will be drilled 25 feet into solid bedrock,” Schnoebelen said.

Specialized Equipment Required

Such a big bridge project demands very specialized drilling equipment, which will come from Steven M Hain Co. Inc. of Garland, TX.

The star of the six to eight cranes on the site will be a Manitowoc 7000 crane. “I think there were seven built and we own two of them,” he said. “Most, if not all of the cranes, will be Manitowoc.” The 7000 is too large to travel by roadway and a barge was specially fabricated to carry this crane. The 7000 will sit on a steel ring, allowing the boom to swivel. This ringer crane is so large, that it requires a counterweight of 552,000 lbs. before any load is added. It is rare for a crane this size to be used for a construction project in an inland waterway.

Risky Business

“The contractor has to consider all these factors when bidding a project,” Horn said. “There’s a lot of risk in building a river bridge because they’ve got these cranes out there that cost a ton of money. If you are flooded for six months and those cranes are out there being unproductive, it costs the contractor a ton of money. He has to figure in his bid all the risks — what are all the things that could happen? How many days are they likely to be shut down for flood? How many days are they likely to be close down for wind?”

Those unknowns make bridge construction all the riskier, Horn said. “All of our highway projects — we let four a month — so we know exactly what it takes to build those,” he said. “But bridges like this you only build once in every several years, and there are a lot more challenges.”

MoDOT received only two bids for the work, Horn said. “We had four (contractors) interested in it that were pre-qualified to bid, but in the end only two submitted bids. It probably costs over a million dollars just to bid because of the engineering required just to determine the costs.”

Horn said he’s “very confident we have probably one of the best bridge builders in the world with Massman,” adding: “They understand this river. They built the Cape (Girardeau) bridge, they built the Greenville, Miss. bridge, and they built the Alton, Ill. bridge so they know how to work in this river.”

Drivers won’t need to find new routes they way they did during the recent two-year shutdown of I-64/Highway 40. The impact on traffic during bridge construction will not be very great, Horn said. “There will soon be closures of I-70 to take down bridges over Cass, St. Louis and Madison Avenues, but that will be done on weekends,” stated Horn. “However, crews will close the reversible lanes for several months next summer to rebuild them,” he added.

“Two years from now we’ll let the Missouri interchange to tie the ramps into I-70 so we’ll have some lane closures and maybe another 70 weekend closure,” Horn said. “So it’s going to have a huge impact in a short duration of time and we’ll try to keep it out of rush hour.”

Horn is hesitant to say how many jobs the project will produce. “Probably more than 100,” he said. “There will be times where you’re going to have a lot of people out there to pour concrete but other times it will only be a few people. It’s not like I-64 where you had operations going on all over the place over a 12-mile stretch, but concentrated in one area,” he said.

“But there again that’s just the bridge. We have 30 other projects that are going on the Illinois side and the Missouri side to make all these connections. The bridge is the $239 million piece out of the $640 million and these other projects are going to create jobs too.” A Regional Commerce and Growth Association study shows that in the next 45 years the new bridge will create 2,500 jobs, he said. “This bridge project is an economic boom to the region,” said Horn.