Wednesday, December 29, 2010

Engineering Marvel!

John James Audubon Bridge - December 30, 2010

John James Audubon Bridge - December 30, 2010

John James Audubon Bridge Rendering

John James Audubon Bridge Map

Workers carefully lowered the final girder into place Wednesday for the John James Audubon Bridge over the Mississippi River, linking Pointe Coupee and West Feliciana parishes with a ribbon of steel and concrete rather than just a ferry crossing.

Opposing spans of the bridge gradually have extended from the east and west banks for most of this year and finally neared each other within the past week.

“We set one girder last night, so we know it fits,” Project Manager Frank Daams joked as workers prepared to lay the girder on the downstream side of the span Wednesday morning.

Bridge workers paused for photographs in front of the 45,000-pound steel beam before a crane moved it into place with guidance from a construction crew on the deck. The girder was decorated with a large banner noting the milestone.

The main span — 1,583 feet in length — is the longest cable-stayed span in the Western Hemisphere.

“It’s an engineering marvel,” said Richard Savoie, chief of the state Department of Transportation and Development’s engineering section.

Savoie said the key features of the bridge are the two 500-foot-tall towers built a short distance from each bank and their foundations, which extend deep into the river bottom. The massive cables that hold the bridge deck and girders in place are anchored to the towers.

The cable-stay design allows the bridge to cross a busy waterway without causing any hindrance to the barge traffic passing beneath, Savoie said.

“It doesn’t hinder commerce at all,” he said.

Motor vehicles now cross the river between New Roads and St. Francisville on a ferry that will cease operations when the bridge opens.

Louisiana voters approved the bridge and 15 other projects in 1989 in a package called the Transportation Infrastructure Model for Economic Development, known as TIMED, and funded by a 4-cent-per-gallon gasoline tax.

Audubon Bridge Constructors, a joint venture of Flatiron Corp., Granite Construction and Parsons Transportation Group, won the competition to both design and build the bridge.

Work began in May 2006, and Louisiana TIMED Managers, consultants for DOTD, now estimate the project will be finished in late 2011, spokesman Bill Grass said.

Grass said the most recent cost estimate for the bridge is $409 million.

Although the spans are now connected about 130 feet above the middle of the river, the bridge still is not accessible to vehicular traffic because additional work is needed to complete the deck.

Now that the spans are connected, “a lot of adjustments” will be needed to the alignment, Daams said, and the remaining opening between the two sections may not be completely bridged until next week.

“The east span has been pulled back a bit. We’ll let it come back tomorrow,” Daams said.

While crews worked to tie the spans together, other workers were busy preparing the additional cables that will be attached to the new girders.

The total length of the bridge and its approaches will be 2.44 miles, consisting of four lanes with 8-foot outside shoulders and 2-foot inside shoulders, according to an LTM news release.vThe project also includes 12 miles of new roadways that will connect U.S. 61 in West Feliciana Parish to La. 1 in New Roads. The route required construction of seven smaller bridges on the east bank.

The new 9-mile La. 10 connector in Pointe Coupee offers better access to three existing roads, La. 1, La. 10’s business route and La. 981, an LTM news release says.

The Pointe Coupee section may open for local traffic in January or February, Grass said.

“I think this is fabulous. This is a big moment for West Feliciana and Pointe Coupee parishes, and really the whole Zachary Taylor Parkway,” said Scot Byrd, economic development director for the Greater Pointe Coupee Chamber of Commerce.

The bridge is the centerpiece of the proposed parkway, for which supporters envision having La. 1 and La. 10 widened to four lanes between Alexandria and Interstate 59 in Mississippi.

The Audubon bridge is the eighth Mississippi River crossing wholly within Louisiana, the LTM news release says, while bridges also cross between Louisiana and Mississippi at Natchez and Vicksburg.

The Louisiana Legislature named the bridge after John James Audubon, who painted 32 of his “Birds of America” series while residing at Oakley Plantation in St. Francisville in 1821.

A movement is under way to rename the span in honor of Lt. Gen. John A. Lejeune, of Pointe Coupee Parish, and Gen. Robert H. Barrow, of West Feliciana, the 13th and 27th commandants of the U.S. Marine Corps, respectively.

Check out the article at The Advocate.

What an impressive display of engineering this is! I can't wait to drive across it once it's completed!

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