Audubon Takes Flight

Advantages of Cable Stayed Bridges

2008-08-26T21:14:37.5360000+01:00

The method of construction of a cable stayed bridge is faster and simpler than that of a suspension bridge. The advantage of the cables being connected directly to the bridge deck and not draped like a suspension bridge allows building a lighter deck which saves money. The draped cables of a suspended bridge are enormous and incredibly heavy and require equipment such as helicopters or cableways to install. There is no need for this kind of equipment when draping the cables of a cable stayed bridge from one tower to the other because the cables are smaller and easier to install. The process involves laying the cables down on the deck and raising them to the towers to make the connection. At the beginning of the project you have a small bridge deck and short cables to install. Towards the end of the project you have longer cables to install but already have the longer deck constructed cantilevering from the towers.

The cable stayed bridge does not need big anchorages, because the bridge deck is attached to a multitude of cables that are directly connected to the towers. The more cables that are used means smaller forces to be carried and therefore smaller anchorages are sufficient. A suspended bridge is connected by two main cables, with other cables transferring the load from the deck to the main cables. Therefore they carry an incredible tension force that must be resisted by big anchorages placed at the two extremities on land.

In conclusion, from 750 ft up to 3000 ft a cable stayed bridge represents the best technical and economical solution. The project is scheduled to be complete in 2010.

Cable-Stayed vs Suspension

2008-07-22T15:48:25.7580000+01:00

The John James Audubon Bridge will be the longest cable-stayed bridge in North America . Have you ever wondered what the differences are between a cable-stayed bridge and a suspension bridge? This is a question that is asked frequently.

A cable-stayed bridge consists of one or more towers with cables supporting the bridge deck. The cable-stay design is the optimum bridge for a span length between that of cantilever bridges (a bridge that has structures that project horizontally into space, supported on only one end) and suspension bridges (a type of bridge where the main load-bearing elements are hung from suspension cables). Within this range of span lengths a suspension bridge would require more cable, while a cantilever bridge would require more material, thus increasing the cost of the project.

A cable-stayed bridge may look similar to a suspension bridge, but in fact is very different in principle and in the method of construction. The cables form the primary load-bearing structure for the bridge deck in a suspension bridge design. In a cable-stayed bridge design, the towers form the primary load-bearing structure.

The State of the Art in Cable Stayed Bridge Construction

2008-06-23T21:12:31.8220000+01:00

The John James Audubon cable stayed bridge will incorporate many advanced features that represent the state of the art in cable stayed bridge construction. These features include the galvanized strands for the cables, the high density polyethylene stay pipes with an external helix for wind stability, the anchorage system of the cables inside the towers with steel anchorage boxes, the single inspection traveler running along the bottom of the whole deck, the provision of elevators inside the towers, the simplicity of design of the towers and of the deck, and the efficient semi-fan arrangement of the cables. All of these features are combined with the most advanced design provisions for withstanding extreme events like vessel collision, hurricane force winds, sudden loss of one cable or the scouring action of the river.

Bridge to Stimulate Economic Growth

2008-05-06T14:06:07.2960000+01:00

The Audubon Bridge project, as with all TIMED projects, was strategically chosen to be built in order to stimulate economic growth across Louisiana . By stimulating economic development this will help to strengthen the communities of New Roads and St. Francisville, as well as other communities in this area.

From a policy perspective, economic development can be defined as efforts that seek to improve the economic well-being and quality of life for a community by creating and/or retaining jobs and supporting or growing incomes and the tax base. It typically refers to improvements in a variety of indicators such as literacy rates, life expectancy, and poverty rates.

High Water Does Not Stop Bridge Progress

2008-04-22T21:52:32.9040000+01:00

Construction of the work trestles (a structure consisting of spans supported upon frame bents) at the Mississippi River crossing is at a standstill due to the high water, but work continues on the 12 miles of two-lane roadway approaches and 8 conventional bridges that will connect LA 1 east of Hospital Road at New Roads to US 61 south of LA 966 at St. Francisville.

Work is being done in the Prefabrication Yard where testing is being performed on the jacking system used for lowering and raising pre-cast formwork panels. Piles (a shaft-like linear member which carries loads through weak layers of soil to those which are capable of supporting such loads) are currently being driven for many of the conventional bridges. Grading and drainage work continues on the west side.

Work on the trestles will resume when the water level is safe to do so and is being monitored daily for changes in the water level. Once these work trestles are complete this will allow crews to continue work on the main bridge structure despite river conditions.

Box culverts on the west side. On the right side, surcharge soil has been placed on the embankment for compaction.

A Pier of the Main Span is underwater. The river has flooded the side on the East bank.

The foundation shafts and the access ramp to the trestle are underwater. The trestle is just above water.

A pier of the Main Span. Only the top of the shafts are visible. The access trestle on the left is at elevation +54 ft and is a few feet above water.

View of the west access to the Main Span. The west storage area is visible at the top of the photo, beyond the levee and LA 981. The protruding pipe piles are the top of the templates needed for the installation of the shafts. The top of the steel casing of the shafts is barely visible in the river.

Photos provided by Tommy Comeaux with The Pointe Coupee Banner

Did You Know?

2008-04-02T14:24:45.5900000+01:00

Did you know that the John James Audubon Bridge will be the longest cable-stayed bridge in North America ? A cable-stayed bridge is a bridge that consists of one or more columns (normally referred to as towers or pylons), with cables supporting the bridge deck. The bridge will serve as the only bridge structure on the Mississippi River between Natchez , Mississippi and Baton Rouge , Louisiana (approximately 90 river miles). The John James Audubon Bridge will also be the first design/build project for the LA DOTD. This means that a single entity provides all of the services necessary to both design and construct all or fundamentally design/build from other forms of project delivery. Because the Engineers and General Contractor are on the “same team” in a design/build environment, design/build offers many advantages to the owner including price and schedule control early in the design process.

John James Audubon is a monumental figure to the people of Pointe Coupee and West Feliciana parishes. Audubon dedicated his life to painting all of the birds in America . He painted 32 of his famous works in his “Birds of America” series while residing at Oakley Plantation at St. Francisville as a tutor to Eliza Pirrie in 1821. As these two parishes are widely known for their abundance of wildlife, amazing landscapes and preserved historic structures from the days of Audubon, it is only fitting that the new bridge be named in his memory.

THE PEOPLE OF TIMED & AUDUBON BRIDGE

2007-09-12T16:51:50.9800000+01:00

The TIMED Program has wrapped up another fiscal year. It was a year of progress, successes and milestones.

In deciding a theme for this year’s annual report, we debated catchy phrases and ideas but always came back to one asset of the Program: the people who work everyday to ensure TIMED routes are designed and constructed and the people who live, work and travel along these corridors.

We felt it was important to capture their faces, their names and their stories.

At the peak of construction, the Audubon Bridge project will host several hundred employees, a vast majority from Louisiana communities. Many you know. Some likely live in your neighborhood.

Some have come from the far reaches of the globe. People like Dante Lius, the project’s resident engineer from Italy .

And now that construction is underway, the communities of New Roads, St. Francisville and alike are beginning to feel the effects. Locals are talking about the project, the progress and the positive change the bridge will bring to their businesses and everyday lives.

Teachers at local schools are educating their students about the Audubon Bridge , an engineering marvel and a record-breaking project many people never have the opportunity witness.

One elementary student, Kellie Mounger, participated in the Junior Engineer Design Contest we introduced this spring. Not only did she draw a picture of a bridge spanning the Mississippi River, she included a paddlewheel floating under the structure…truly Louisiana . An artist at heart, Kellie tells me she is learning from the project. She’s learning about bridge design and construction.

And so, that’s what the TIMED Program is all about. It’s much more than widening highways and building bridges. It’s about connecting communities. It’s about engaging residents and educating students.

After all, this is Louisiana ’s program. >

JUNIOR ENGINEER CONTEST A SUCCESS!

2007-04-16T16:18:29.2260000+01:00

Involving the community and keeping residents (particularly the locals) engaged in this massive project has always been a top priority for me. It’s important you know what’s happening and when. Many of you see activity all around you…equipment moving, progress on the construction site and new faces in town.

Engaging the youth of the area is critical as well.

The recently completed “Junior Engineer Design Contest” was a huge success! The initiative, targeting children ages 5-11, asked participants to draw and color the Audubon Bridge the way they see it. The guidelines, left open-ended, encouraged creativity and imagination.

While called a contest, all participants were winners and everyone received a prize packet filled with project trinkets and a letter of appreciation for his or her efforts. To be honest, I anticipated receiving 30 or 40 entries…never the 150+ actually received!

Children from several communities in Pointe Coupee and West Feliciana mailed in entries and many teachers from local elementary schools worked closely with their students to complete the activity. I never imagined the overwhelming participation, but am pleased so many people are taking interest in the project.

Designs submitted ranged from the cable-stayed design of the Audubon Bridge to the suspension design of the Golden Gate Bridge and the truss construction of bridges such as the Mississippi River Bridge at Baton Rouge and the Huey P. Long Bridge near New Orleans .

Details from a few submissions included ornate iron work, hanging pot plants, mounted flags and a paddlewheel boat decorated in LSU purple and gold floating beneath the bridge!

Look for the best entries in future project promotions! >

SAFETY: THE MOST IMPORTANT ISSUE

2007-01-08T14:19:40.1550000-00:00

For contractors, project managers and owners, safety on the job site is often the most important issue.

On the Audubon Bridge project, it has been said time and time again. Safety is the #1 issue…PERIOD.

Over the duration of the project, safety is discussed at most meetings, partnering sessions and is tracked and documented by a safety manager and his staff.

Crews are briefed each week, new employees to the job site must attend a mandatory safety orientation and all workers must adhere to the strictest safety guidelines to maintain access to the job.

Today, the Design-Build team—Audubon Bridge Constructors—has decided to go a step further, shut the entire project down and focus on safety education.

Various booths are setup at the main project office for crews to review the latest safety guidelines, equipment and practices. Safety personnel are expected to address employees and reiterate that safety on the job site is paramount.

Shutdowns for safety education are expected periodically over the duration of the project.

I applaud the Design-Build team’s efforts to ensure their job site is secure and safe for all employees and site visitors.

2007: A NEW YEAR FOR PROGRESS

2007-01-02T14:28:09.8960000-00:00

Nearly eight months have passed since the groundbreaking ceremony and we now enter a new year—2007.

As I’ve mentioned before, 2007 will be an exciting year for the project. In addition to the clearing and preliminary construction that has occurred already, the cable-stayed bridge will begin to take shape.

There will be much to see and it will be exciting!

Beginning this month, a newspaper series entitled “Meet the Bridge Builders” will appear in the area’s local newspapers, the Pointe Coupee Banner and the St. Francisville Democrat.

Through this series, we hope to offer you an opportunity to see who is responsible for building the Audubon Bridge . What are their names? Where are they from? What other projects have they worked on?

Many of the project’s top brass have worked on projects all over the world and are considered among the industry’s best.

If you do not live in Pointe Coupee or West Feliciana parish or receive either of the newspapers, there is no need to worry. The series will be posted to this Web site.

In the meantime, if there is any question you have on the project or something more you want to hear about, feel free to leave me a comment.

Happy New Year!