For many Louisiana residents and commuters, a long-time dream will soon come true. For the Louisiana Department of Transportation and Development (LADOTD), an additional component of its largest transportation program in history will be completed and open to traffic.
The John James Audubon Bridge project, a new Mississippi River crossing and 12 miles of roadway approaches connecting two south central Louisiana communities, is under construction. The project is named after the famed naturalist painter who completed 32 paintings of his Birds of America series while residing near St. Francisville. Groundbreaking ceremonies headlined by Gov. Kathleen Babineaux Blanco and LADOTD Secretary Johnny Bradberry were held in May 2006.
To residents of these two historic river settlements, the John James Audubon Bridge will—for the first time in history—provide a permanent transportation structure across the Mississippi River between Natchez, Miss., and Louisiana’s capital city, Baton Rouge. The bridge also will bring an end to centuries of ferry travel. Since the settlement of communities on both banks, residents have ferried across the river at nearly the exact location of the new bridge’s alignment. In recent decades, the LADOTD-managed ferry system has proven costly to operate, subject to mechanical failure and fluctuating river depths and problematic for commuters.
TIMED right
The Audubon Bridge has been long awaited. Locals claim the project has been discussed since the mid-1960s.
“Even as the contractor began to mobilize equipment last summer, some residents were still not convinced construction would actually begin,” said Dana Newsome, a project spokesperson. “More than 400 people attended the groundbreaking to watch as the first shovels of dirt were turned.”
For Louisiana’s Transportation Infrastructure Model for Economic Development (TIMED) Program, the John James Audubon Bridge serves as a centerpiece. The $4.7 billion TIMED Program includes 16 legislatively mandated transportation projects strategically chosen to stimulate economic growth across Louisiana.
When complete, the Audubon Bridge is expected to be the longest cable-stayed bridge in the Western Hemisphere with a 1,583-ft mainspan.
The project is more than a record-breaking structure for the state of Louisiana. In addition to being the latest crossing on the lower reaches of the Mississippi River, the project is the first use of design-build project delivery for the LADOTD.
In 2004, 15 years after the creation of the TIMED Program, legislation was passed allowing the LADOTD to utilize design-build specifically for the future John James Audubon Bridge. Act 81 of the 2004 Louisiana Legislative Session amended the state’s existing design-build legislation to include the Audubon Bridge project.
One of the stipulations of the original legislation, not common in most states, required proposing teams be a single legal entity and acquire necessary licensure prior to submitting a letter of interest and their statement of qualifications.
“The single entity was required to be licensed with the Louisiana Professional Engineering and Land Surveying Board in addition to the State Licensing Board for Contractors,” said Chuck Duggar, project manager. “This requirement was a first for many of the interested teams.”
Another condition of the Louisiana legislation called for a two-stage selection process. An initial design-build evaluation committee reviewed the initial statements of qualification and determined the short list. An independent technical review committee then was established to evaluate the proposals against the performance specifications, the technical requirements and the design options.
The design-build procurement called for both performance specifications and design options, including options for the actual bridge structure. These criteria allowed for variables in the proposals and resulted in proposals with varying mainspan lengths, drilled shaft vs. caisson foundations and single pylon vs. H-frame designs. The request for proposals also called for proposers to submit two option bids with varying options for the approaches. One called for four-lane approaches while another called for two-lane approaches. The final decision to exercise the option for the four-lane approaches was made by the LADOTD based on cost effectiveness after the price proposals were opened and the apparent winning team was determined.
“Legal organization and financial capability were rated on a pass/fail system,” Duggar stated, “while all other factors received an adjectival rating. A cumulative adjectival rating was determined and ultimately converted to a numerical score.”
Price proposals were reviewed in a public opening March 2, 2006, and an overall adjusted score was calculated for each proposal. The overall adjusted score was calculated by dividing the lump-sum price by the composite technical score. The proposal receiving the lowest adjusted score was the apparent winner and was ultimately awarded the contract.
The design-build process kicked off in 2004 and led to the LADOTD inviting three short-listed proposers to submit written technical and sealed price proposals for the project. The final selection was announced March 2006 when the sealed price proposals were opened and scores calculated with the overall technical scores. In the end, the design-build procurement process worked well for Louisiana. The selected team, Audubon Bridge Constructors, had both the lowest price bids on both options for the approaches and the highest technical score. As a result, the LADOTD was able to exercise the option for the four-lane approaches.
The team is a joint venture of Flatiron Constructors, Granite Construction and Parsons Transportation Group (PTG). PTG is the designer of record for the project. In keeping with the 1989 TIMED Program legislation, several local subcontractors are working on the project. The original legislation mandates 80% of all construction workers must be Louisiana residents.
A component of the TIMED Program, the project is being managed by the first large program management contract for the LADOTD. The program manager, Louisiana TIMED Managers, is a joint venture of Parsons Brinckerhoff, the LPA Group Inc. and G.E.C. Inc.
Moving at hurricane speed
While the process culminated in a positive result, the entire project stood to be derailed in 2005 with the impacts of hurricanes Katrina and Rita. When the hurricanes of 2005 devastated the Gulf Coast, contractors were overwhelmed with emergency contracts. Equipment was scarce. Materials were in high demand. Prices skyrocketed. Proposals had just been requested from the short-listed teams. The project had just been advertised when Hurricane Katrina struck the region in late August 2005.
“Industry leaders and national contractors attended pre-proposal informational meetings for the project and questioned whether it could be bid within reasonable estimate,” Duggar noted. “Many questioned if any proposer would submit qualifications.”
Because of due diligence by the LADOTD, the budget was revised taking into consideration the post-hurricane market. The project procurement stayed on course with only a minimal 60-day delay. Three responsive proposals were received for the project and the lowest price proposal was below the revised LADOTD estimate.
Since the hurricanes of 2005, additional awareness has been placed on design-build delivery in Louisiana. Legislation was passed in 2006 allowing for design-build delivery to be utilized on emergency transportation projects related to hurricane recovery.
The design-build procurement process also has been revised since the Audubon Bridge procurement, providing for a streamlined and improved design-build process for future transportation projects in the state.
The design-build team has made significant progress since Notice to Proceed was granted in May 2006. The clearing and grubbing of the roadway approaches—over 12 miles of virgin land—is well under way. Both the east and west bank alignments have been cleared, and a haul road is being built for transporting construction equipment and materials.
Construction of work trestles on both banks of the river also is progressing. The temporary trestle structures will serve as work platforms from the land to the location of both piers in the river and provide land access to river pier locations for construction of foundations and substructure.
“The trestles offer the design-builder land-based access regardless of fluctuating river heights and currents,” said Dante Lius, resident engineer. “Once the trestles are complete, construction of both piers can progress with less need for barge-based equipment. This results in a less-interrupted construction cycle with less dependence on river levels.”
The eastern trestle will extend approximately 420 ft, including the work platform around the footing, from the river bluff and provides protection for and access over concrete revetment mats installed by the U.S. Army Corps of Engineers. The western trestle will stretch approximately 1,100 ft across batture lands to the western pier location. A 375-ft earth ramp will connect the trestle to the levee. The trestle tops will sit at EL +50, approximately high-water elevation.
“On the Audubon Bridge project, the trestles allow for land-based construction of both the main river and back piers,” said Lius. “This will increase the design-builder’s ability to work during high water.”
In addition to the cable-stayed bridge across the Mississippi River, the Audubon Bridge project includes 12 miles of roadway approaches with seven conventional roadway bridges over creeks, tributaries and a railroad spur. Pile driving began last fall on a 585-ft roadway bridge, and construction is scheduled to begin on a second 415-ft bridge in the next few months. The roadway approaches, including the seven bridges, are planned to be complete by summer 2009, approximately a year ahead of the cable-stayed bridge.
A series of technical and performance solutions outlined in the design-build procurement plan helped produce the cable-stayed bridge’s eventual design and 100-year service life.
The bridge’s H-frame pylons will tower over 500 ft tall and be erected by means of hydraulic falsework one segment at a time, 32 segments per pylon.
The design-build team opted to utilize drilled shafts rather than caisson foundations, a first on the lower reaches of the Mississippi River. The 21 drilled shafts for the foundation of each pylon will be 8 ft in diam. Shafts for the eastern pier will be 185 ft in length; 180 ft for the western pier.
“The piles are designed to withstand barge collision and the scouring of the foundations by the river,” said Lius.
Lius, who served as resident engineer for the main span of the Arthur J. Ravenel Jr. Bridge over the Cooper River, noted navigability of the river on the Audubon Bridge project—unlike that of the Cooper River bridge—does not require rock islands surrounding the piers.
Rock will be placed on the river bottom, however, to repair and protect the existing revetment mats and scouring.
The bridge deck will be supported by 136 cables, 68 per pylon. Each cable will be made of up to 75 sheathed strands made of seven galvanized and greased wires measuring 0.6 in. in diam.
“The strands will be protected by a high-density polyethylene pipe for additional protection from corrosion, ultraviolet rays and wind vibration,” Lius noted.
The bridge will sit 65 ft above high water, which will accommodate river traffic in the area. Ocean-going vessels can only navigate the Mississippi River as far north as Baton Rouge, approximately 30 nautical miles downriver from the Audubon Bridge. Continued river access is restricted by the height of the U.S. Highway 190 bridge crossing at Baton Rouge.
Materials and equipment for the project are expected to come from all over the world.
Cement for the drilled shafts and pylons will come from Thailand, while structural steel for the main span will be delivered from Japan. In addition, the oscillator for driving the casing of the drilled shafts was shipped from Germany, and the wind tunnel analysis by Rowan Williams Davies & Irwin Inc. was performed in Ontario, Canada. The mainspan design is being performed by Buckland & Taylor Ltd. of British Columbia, Canada.
“It is not unusual for a bridge of this size to be a true global effort,” explained Lius, a native of Italy.
Despite escalating construction costs and industry uncertainty following the hurricanes of 2005, the $406 million Audubon Bridge project is under construction and on schedule to be completed in the summer of 2010.
