The New Mississippi River Bridge (NMRB), currently under construction, is a 1,500-ft. (457 m) span that will link downtown St. Louis, Mo., to East St. Louis, Ill. When completed in February, 2014 it will be the third longest cable-stayed bridge in the United States.
The $667 million co-project of the Illinois and Missouri departments of transportation, is being built by a joint-venture consisting of the Massman Construction Co., Traylor Brothers Inc., and Alberici Constructors. The federal government is covering $239 million of the cost, IDOT covering $313 million and MDOT covering $115 million.
The bridge was designed by Kansas City-based HNTB Corporation and has an expected lifespan of 75 to 100 years. Hans Hutton, HNTB’s chief engineer in the Kansas City bridge office, said that it took less then a year to design the bridge.
“It was a very aggressive schedule for a bridge this complex and this long of a span,” said Hutton. “We always think about constructibility and try to develop details that are easily constructable. The easier a bridge is to build the lower the cost of the structure.”
The design for the NMRB takes into account contractor concerns, such as the use of pre-cast deck panels to decrease “the amount of time it takes to construct the superstructure. The use of precast deck panels is common for cable-stayed bridges. Utilizing precast panels decreases the construction time and the amount of creep that the concrete deck incurs during the erection cycle.”
This project also uses steel anchor boxes for the upper cable anchorages, which Hutton said greatly reduces the congestion in the upper region of the pylons.
“We did this to minimize the amount of post-tensioning and congestion in the upper portion of the pylon,” he said. “Reinforced concrete with a high degree of post-tensioning is very problematic for the contractors. This is an example of where we listened to contractors and changed the way we designed this type of bridge to make their life easier, reduce the overall cost and the duration of the project.”
Hutton stressed the importance of consulting general contractors on design and materials.
“We always try to learn what we can from the contractors as to what they liked, what they didn’t like, if there was a particular detail that caused them problems or a detail that they liked, in the attempt to produce a better design next time — realizing that that we’re never perfect and that contractors have great insight.”
He added that the project has been a success because of the teamwork between the DOTs and joint-venture partners.
Massman, a 108-year-old company, has built hundreds of bridges and has been a participant in the ongoing dialogue with bridge designers and is enjoying the benefits. The joint-venture was awarded the contract in January, 2010 and construction of the bridge began in March of that year.
The bridge will have two lanes in each direction, but because there are wide shoulders on either side, each direction can be expanded to three lanes. The structure is needed to relieve traffic in the St. Louis area as the current Poplar Street Bridge handles traffic from three converging interstates — I-70, I-55 and I-64. The NMRB covers I-70 traffic.
On the Illinois side, the approaching roads are being built on greenspace, while on the St. Louis side, the roads are passing through a warehouse district where some expropriations took place. The roadwork for the bridge approaches, completed last year, was the result of two contracts awarded Keeley and Sons Inc. and Keller Construction Inc. for the Illinois approach and Fred Weber Inc. for the Missouri approach and part of the Illinois approach.
According to Mark Schnoebelen, a Massman vice president and project sponsor of the partnership, the new bridge will require 15 million lbs. (6.8 million kg) of structural steel and 43,000 cu. yds. (32,876 cu m) of concrete. In terms of recycling, only temporary construction materials such as engine oil, steel, and wood products will be dealt with.
The water levels of the Mississippi have posed problems for the cable-stayed bridge, which consists of four piers — two in the rivers (pylons) and two by the shoreline — anchor piers. Cables, linked via the bridge tower, support decks. The pylons began as coffer dams — steel boxes placed in the river and had the water pumped out of them.
“The high water created challenges keeping the work space dry and made it more difficult to stabilize our equipment in the river because the current was swift,” said Schnoebelen, who added that when the river depth is low, “we encountered problems because certain work we planned on doing from barges became inaccessible. So we revised our construction procedures and erected more of the bridge from the bank than we originally planned on.”
There are approximately 140 construction workers and management officials on site when the partnership and subcontractor crews are maximized. The key subcontractors on this project include MTC Construction, BRK Electrical Contractors, Edwards-Kamadulski, Thomas Industrial Coatings, and XL Contracting.
On a project of this size and scope, where coordination is crucial and safety is a constant concern, meetings are ongoing to ensure each step is followed precisely and that work done is properly inspected.
Mark Dickerson, Massman’s equipment manager, said that his firm and those of the partners supplied nearly all of the equipment needed for the project. Some equipment was purchased, such as 950 Cat loaders from Foley CAT, three Cat TL 1255 telehandlers from Dean Machinery, Foley CAT, and two 60 kW and two 175 kW John Deere generators from CK Power. Some used equipment was purchased at auctions.
Rentals, for occasional periods, included air compressors from Hertz, Volvo Rents, United Rentals and 60 kW generators from CK Power.
“When we purchase welding machines, air compressors, manlifts and other equipment,” said Dickerson, “we normally try to go through local dealers.”
Massman brought in a Manitowoc 7000 crane, a large crane that it was using for a project in Kansas City that has a 400 ft. (122 m) main boom and 80 ft. (24 m) jib on top.
“We needed it to reach the higher tops of the pylons,” said Dickerson, who made sure that every piece of equipment used follows its regularly scheduled maintenance, be it 250, 500 or 1,000 hours. “I inspect the equipment from time-to-time and we also have an onsite equipment superintendent, Glenn Wunsch, who is my eyes and ears, as well as the input of our mechanics.”
Massman usually has two onsite mechanics and occasionally a third. They are needed, as the first 1.5 years of the project had crews working 20 hours per day, six days a week and currently, crews are at work nine hours per day on six-day work per-week schedule.
With work taking place on both sides of the river, a small maintenance shop was set up on the Missouri side, while a fenced-in smaller compound was erected on the Illinois side. Because most of the vehicles and equipment being used are very large, repairs normally take place outdoors.
Massman monitors equipment use via meter readings that are automatically inputted to spread sheets. This was bolstered by daily, weekly and monthly equipment inspections, which includes oil samples.
Save for the drilling phase of the work, minimal unexpected equipment breakdowns have occurred.
“The drilling for the piers was the most duty-cycled type of work that we have done on the whole project,” said Dickerson, who employed two Steven M Hain drills that were crane-mounted.
Massman owns its barges, which were manufactured for them by Conrad, Corn Island Shipyard and New Johnsonville Marine Service. In addition to six to eight material barges and four to five crane barges that are usually on site, tugboats also are employed.
“The barges are similar to what is built traditionally for other companies,” said Dickerson. “We just made some of ours a little bit wider. Our marine operations will be ongoing until the job is almost done.”
The river bed did not pose any problems, with the standard depth being 30 ft. (9 m) and an additional 50 ft. (15 m) of silty sand before reaching the bedrock.
Dickerson also is responsible for safety issues and those are being carried out on a similar schedule to that of the equipment.
Schnoebelen said the project is honing skills for workers and management and providing necessary experience for new employees, while Dickerson, who is based in Kansas City, stressed that “when you have a fairly good-sized project like this, you need an equipment superintendent on site all the time. It makes me feel better because I can’t be there every day or every week.”
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