Photo Credit: Missouri Department of Transportation
I and my fellow bloggers here at DBA (David Graham and Aaron Hudson) try to keep up with the various projects under construction that we had a part of. Sometimes it is hard to do once we have left the site after foundations are complete. Modern information technology makes it much easier, especially since most large infrastructure projects have a significant public outreach effort, either by the project design/build team, or the owning agency.
Massive prestressed concrete girders, some of them setting a record for the longest concrete girders used on a Minnesota bridge, have been set at the New Hastings Bridge, currently under construction in Hastings, Minnesota. The largest girders are 174 feet long, 8 feet tall, and weigh 108 tons! There is a video of one of these huge beams being delivered on a 16 axle truck, below. An article from the December 2011 issue of Concrete Products magazine about the girders can be found here. To date, all of the girders between the north abutment and main span have been placed. Crews are preparing piers 5 and 6 for the main span steel arches, which are scheduled to be floated in by barge and lifted into place late this year. MnDOT has two web cams where the bridge construction and the arch construction can be viewed. The Minneapolis Star Tribune has also been following the construction. Their latest article, which hails the bridge as “a monumental marvel,” can be found here.
The John James Audubon Bridge between New Roads and St. Francisville, Louisiana was officially completed February 27, 2012. The bridge was opened to traffic in May of last year, but was declared officially completed last month. This bridge has a special spot in the heart of DBA as it was one of the early large bridges we worked on as a company. Steve and Dan poured their energy and expertise into the project starting in spring of 2006, all the way to completion of the last foundations in 2010. Steve spent a good part of his life on site during foundation construction. I spent a fair amount of time there myself helping Steve cover things now and then, including observing the soil borings for the main tower piers during the design.
Construction on the John James Audubon Bridge has officially come to a close. The new Mississippi River crossing is the longest cable-stayed bridge in the Western Hemisphere, with a 1,583’ main span. Located in south-central Louisiana, the Audubon Bridge connects West Feliciana Parish with Pointe Coupee Parish and is the only bridge between Baton Rouge and Natchez, Mississippi. Construction on the $409 million project began in 2006 and continued when the bridge was opened in May 2011 due to high water levels closing the St. Francisville Ferry sooner than expected.
"Although the Audubon Bridge has been open to traffic for nine months, it’s with a great sense of accomplishment that we are announcing the end of construction on this beautiful structure," said Department of Transportation and Development Secretary Sherri H. LeBas, P.E. "The completion of this bridge opens economic development in south-central Louisiana and will be a source of regional, statewide, and national pride."
As massive concrete piers rise from the Mississippi river in southeast Minnesota, people have begun to take notice of what will become the longest free-standing tied-arch bridge in North America. A unique project in several respects, the new Hasting bridge has recently been featured in articles on the websites of ENR and Roads & Bridges. The ENR article is a republication of an article that originally appeared in the Minneapolis Star Tribune highlighting the construction process of the last year, with particular focus on the process of constructing the river piers. The Roads & Bridges article is a more technically in-depth piece written by the lead bridge engineer Vincent T. Gastoni, P.E., of Parsons Transportation Group. Both articles discuss some of the many geotechnical changes faced on this project. This excerpt from Roads & Bridges is a concise description of the pier foundations and some of the reasoning behind their selection:
The main river piers are concrete delta-style frames with the tied-arch superstructure fully framed into the pier through the knuckle connection. The stiffness of the foundation system was then integral to the overall force effects in the structure. The north pier is located in 190 ft of soft soils overlaying rock and supported on unfilled 42-in. driven steel pipe piles. Drilled shafts were investigated early but were not cost-effective, impacted the schedule and presented a risk to the existing bridge due to potential caving effects. Statnamic pile load testing was used to validate the vertical capacity and lateral performance of the 42-in. piles. The south pier footing is close to the rock surface; however, the rock was deeper, more sloped than expected, and the originally planned spread footing was changed to short drilled shafts during the final design. Dan Brown & Associates provided the team with geotechnical analysis and recommendations.
Our Tim Siegel pointed out that the statement “It’s a marvel of engineering that requires ingenious construction techniques, most of which are invisible to the drivers whizzing by overhead,” from the Star Tribune, is an accurate description of how our work as foundation designers and constructors is often viewed. Although much of the ingenuity and innovation that goes into the geotechnical aspects of projects often goes unnoticed by the general public, it is certainly refreshing to see articles like these. For us at DBA, it is even more refreshing to see our efforts credited by name as they were in the article by Vince when he wrote, “Dan Brown & Associates provided the team with geotechnical analysis and recommendations.”
For a design-build project with so many different geotechnical components (driven piles, drilled shafts, spread footings, retaining walls, a column-supported embankment, and light weight fill), it is hard to believe that our role as the lead geotechnical engineer is nearing completion just a little over a year after construction began. At this point, the only foundations that have yet to be constructed are some of the rock bearing spread footings at the south approach. DBA will also monitor instrumentation installed in the column-supported embankment for the next two years.
The article’s lead author, Sereno Brown, P.E., was the construction team’s Project Engineer for the design-build project. In the article, Mr. Brown outlines the issues that led to the team selecting a pre-cast concrete cofferdam over other methods, the design methodology, and then the construction of the cofferdam. The effort posed several significant design and construction challenges, including the sequence of lowering the cofferdam into place through a set of hydraulic jacks. The entire process was truly an amazing engineering and construction feat.
On December 29, 2010, Audubon Bridge Constructors recently “closed” the main span of the John James Audubon Bridge between New Roads and St. Francisville, Louisiana. Watch the video featured at the top of the page at the bridge link to hear about the bridge, including the drilled shaft foundations! For something really fascinating, go to the webcams here and scroll back through the various dates. They have archived images all the way back to start of construction.
Photo: Chris Usery, Figg Bridge Inspectors
The last cables were installed on January 3, 2011 as noted on the project website:
The last two cable stays of the longest cable-stayed bridge in the Western Hemisphere were installed on January 3, 2011, five days after the spans were connected. The John James Audubon Bridge, Louisiana’s newest crossing over the Mississippi River, now has all of its 136 cable stays in place.
This bridge will be the longest cable-stayed bridge in North America when it opens later in 2011. Again, from the project web site:
The spans of the longest cable-stayed bridge in the Western Hemisphere were connected on December 29, 2010, stretching 1/3 of a mile over the Mississippi River. The John James Audubon Bridge, connecting Pointe Coupee and West Feliciana parishes in Louisiana, is approximately 92% complete. Construction of the spans began from both sides of the 500-foot tall towers earlier this year. Both sides continue to progress at a rapid pace, and now the meeting of the spans has occurred.
Steve Dapp and I had the pleasure of working with many great people during our time on site (much more time for Steve than for me!) during foundation construction. One of them, Chris Ursery of Figg Bridge Inspectors, has been great about providing us with photos now and then to keep us updated of some of the details of the bridge construction. Chris has granted us permission to share a few of his recent photos, which are shown below or can be seen in our web albums here.
The new I-70 bridge over the Mississippi River near St. Louis, Missouri is quite the project. When completed, it will be the third longest cable-stayed bridge in the United States, with a 1,500-ft main span. Most significantly for the geotechnical community, the bridge made history when one of its 11-ft diameter drilled shafts resisted a world record breaking 36,000 tons (bi-directional) during an O-cell load test. The bridge has already seen press in Civil Engineering Magazine(July 2010, page 30-32), at ENR.com, and in a post by Robert on this blog. Now, an article by DBA’s Paul Axtell is featured in the September/October issue of Foundation Drilling Magazine. The editor summarized the article saying:
The information in the following article is a composite of material that came to Foundation Drilling Magazine from three separate sources. Part I is based on information gleaned from an article that was published on the Associated Press news wire. Part II is excerpted from ENR’s August 18th, E-Newsletter. Part III was provided by Paul Axtell and Dan Brown of ADSC Technical Affiliate company, Dan Brown and Associates. The bridge project is of interest in general. The Osterberg Load Cell test will be of particular interest to professionals in the deep foundation industry, and specifically for those who work in the drilled shaft segment.
Paul received a few photos of the kcICON bridge that are just too cool not to share. These were sent to him by Massman Construction. These were taken in September of this year. MoDOT’s Flicker album of the dedication ceremony is here. The new bridge was dedicated and partially opened to traffic (southbound) on September 27th. The northbound traffic was shifted to the new structure on October 22nd. All of the bridges and ramps for the project will be opened by the end of the year – 6 months ahead of schedule. Can’t wait to see it after the exisitng bridge is demoloshed, though it is a pretty cool image with the old and new bridges together. Updates for the project are on the project Facebook Page.
Here is the existing bridge that is being replaced (viewing from upstream):
In addition to several relatively large approach spans, the new bridge will include a 545ft long free-standing arch main span with four lanes of traffic and a 12 foot wide common use pedestrian/bike path. The new bridge will allow additional parking and an artistic plaza area south of the river. An anti-icing system will be installed to help achieve the 100-year design life.
On the south side of the Mississippi River, the bridge foundations will consist of spread footings bearing on dolostone bedrock. The remaining bridge foundations will utilize 42in diameter pipe piles. Several Statnamic load tests, both axial and lateral, will be performed by our friends at AFT.
Settlement mitigation is required beneath the North Embankment due to several relatively thick and deep strata of compressible fine-grained soils. The embankment will also be heavily instrumented to evaluate performance of the embankment and mitigation technique.
Preliminary work including subsurface investigation has begun. The subsurface investigation is being performed by Braun Intertec under sub-contract to DBA. Test piles will be installed in early September, 2010 with subsequent load testing soon after.
The awarded design-build contract is for $120M. The estimated project completion date is May 13, 2013.