A lot has changed from a year ago at the TH 53 Bridge sight near Virginia, Minnesota. This time last year, the design-phase test pile program was wrapping up with three Statnamic load tests and we had just completed our initial geologic field investigation. Since then, significant excavation, rockfall protection, and foundation work has been completed. During summer and fall of 2015, DBA worked closely with contractors Hoover Construction and Pacific Blasting to maintain rockfall protection throughout the East Abutment and Pier 1 (East Pier) excavation process. Official ground breaking occurred last November and foundation work started shortly after. A total of 32, 30-in micropile foundations have been installed by Veit Specialty Contracting and Kiewet Infrastructure has completed a temporary causeway across the massive Rouchleau Pit by placing over 300,000 cubic yards of fill.
With the foundations of both piers complete, and the pier towers are starting to rise up, where they will carry the bridge deck 200 ft above. The abutments are also taking shape with rock bearing concrete footings now poured on both sides of the pit. The only foundation work left is to install tieback anchors at the East Abutment, which will reduce the lateral loading of the tall piers.
In a little over a year, the bridge is scheduled to open to traffic. You can keep track of the progress through the project web cam.
The St Croix Crossing Bridge is an extradosed bridge, which is something of a cross between a segmental box girder and cable-stayed bridge. The scale of the massive concrete segments can be seen in the picture above in comparison to the barge the segments are sitting on and some of the equipment in the background.
Construction of drilled shafts continues as the superstructure begins to emerge over the skyline between Elizabeth, NJ and Staten Island, NY. The new bridge will be a dual-span 1,983-ft long cable-stayed bridge with approach spans of over 2,500 ft on each side. The bridge is supported on over 200 drilled shaft foundations ranging in diameter from 4.5 ft to 10 ft and socketed into Passaic Formation siltstone.
The GBR is a Public-Private Partnership (P3) that represents a major milestone for the PANYNJ in its distinguished history of bridge building in the greater New York City metropolitan area. The existing Goethals Bridge along with the Outerbridge Crossing and the Bayonne Bridge comprise the three Port Authority bridges connecting Staten Island with New Jersey. The Goethals Bridge and the Outerbridge Crossing are cantilever truss structures and both opened on the same day in 1928. They were designed by J.A.L. Waddell under the supervision of the eminent engineer Othmar H. Ammann (1879-1965), who was the designer of many other iconic bridges in the NY City area including the Bayonne Bridge (1931), the George Washington Bridge (1931), and the Verrazano Narrows Bridge (1964). The designer of record for the replacement Goethals Bridge is Parsons Corporation, which is the successor firm of Robinson & Steinman, whose principal David B. Steinman was also a notable NY area bridge designer and a contemporary and rival of O.H. Ammann.
Each main pylon tower of the GBR is supported on a group of six 9-ft diameter drilled shafts and each anchor pier is supported by two 10-ft diameter shafts. Approach piers are two-column bents with each column supported on a rock-socketed drilled shaft.
DBA is the foundation design engineer of record and this project provides an example of how rock-socketed drilled shafts can provide a reliable and cost-effective means of supporting a major bridge by taking advantage of the high resistances that can be achieved. Key factors involved in taking advantage of rock sockets for this project were: (1) load testing to demonstrate high axial resistances (>30 ksf side resistance and >300 ksf base resistance), (2) utilization of all relevant construction QC/QA tools to ensure that rock sockets are constructed in a manner that is consistent with construction of the load-tested shafts that provide the basis of the design, (3) close collaboration between all members of the design-build team, and (4) adequate subsurface characterization, especially a thorough characterization of rock characteristics and their effect on socket resistances. Load testing for this project demonstrates that side and base resistances can be used in combination to design rock socketed shafts for axial loading. This approach avoids the use of unnecessarily deep sockets, thereby minimizing the associated construction risks and costs.
TH 53 Bridge, artistic rendering courtesy of MnDOT
The official groundbreaking for the Trunk Highway (TH) 53 Bridge and Relocation Project occurred last week at the project site in Virginia, Minnesota. The bridge, which is the main element of the project, will span the Rouchleau Iron Ore Mine Pit. The project is scheduled to be completed in a brisk two years in order to allow for mining where a section of TH 53 is currently located. Upon completion the 1,100-foot long bridge will be Minnesota’s highest, with the roadway sitting approximately 330 feet above the bottom of the floor of the Rouchleau Pit. Kiewit was selected as the general contractor for the project with Veit Specialty Contracting as the foundation contractor.
Foundation construction will start in late November or early December with the installation of 30-inch diameter micropile foundations for the western pier of the three span, steel plate girder bridge. Although the foundation work is just about to get started, DBA has been hard at work on the project for over a year. DBA first got involved as a consultant to MnDOT for the design-phase load test program conducted last fall. Since then, DBA was contracted as the geotechnical engineer of record for the project. Working with bridge designer Parsons, DBA designed the bridge foundations, an anchored abutment, and rockfall hazard mitigation systems for this geologically challenging site. DBA has also analyzed several soil and rock slopes to verify stability of the bridge and roadway.
Most recently, some of us were on site to inspect some of the rockfall protection elements on the east side of the mine pit. Last week we spent two days climbing and repelling a on a portion of the eastern highwall, which is currently covered in rockfall protection drapery. The drapery was installed for the protection of workers excavating rock for the eastern bridge pier. The drapery was installed by Pacific Blasting in association with Hoover Construction. Some pictures from our drapery inspection visit are below.
For more information about the project, click here, and for our previous blog posts on this project, click here.
John and Paul provide some scale to this picture as they work their way down the drapery.
John concentrating as he inspects the drapery seam as he decends.
DBA is currently working with structural designer Parsons to design what will be Minnesota’s tallest bridge. The bridge will span the currently inactive Rouchleau open pit iron ore mine near Virginia, Minnesota. MnDOT is moving the alignment of the existing Hwy 53 to make way for future mining in the area. DBA is the lead geotechnical designer on the project in addition to being contracted as MnDOT’s load test expert for the ongoing design phase load test program.
As part of our site investigation to gather information on rock fall and the site geology, five DBA engineers (John Turner, Paul Axtell, Tim Siegel, Nathan Glinksi, and David Graham) got up close and personal with the site by rappelling off the near vertical cut faces on either side of the Rouchleau pit! Traversing the over 200-ft tall cut faces of the nearly 2-billion year Biwabik Formation rock formation by rope and harness, we collected valuable geologic data. We also took some great pictures like the ones posted to our Google Photos account. In addition to the still pictures, we took some videos of a few rock fall tests, which are on our YouTube channel.
If you would like to know more about this interesting project on Minnesota’s Iron Range, you can check out our project summary sheet, visit MnDOT’s project page, or stay tuned to this blog for more updates. There is also an online article about the project that was recently published by Civil Engineering Magazine.
DBA has had the pleasure of working with T.Y. Lin and Slayden–Sundt JV in their effort to replace the Sellwood Bridge over the Willamette River in Multnomah County, Oregon, near Portland. Designed by Gustav Lindenthal, the existing Sellwood Bridge was constructed in 1925 to replace the Spokane Street Ferry, connecting the communities of Sellwood and West Portland. In response to budget issues at the time, the Sellwood Bridge design was scaled back to minimize costs. Fast forward to 2014 and the existing Sellwood Bridge is now the only four-span continuous truss highway bridge in Oregon and possibly the nation. The bridge is extremely narrow, two lanes, no shoulder or median, and one small 4-ft sidewalk. In addition to these shortcomings in design with respect to the modern age, the west end of the bridge was constructed on fill, and the hillside above the bridge is now slowly sliding toward the river. Ground movements have caused some of the girders to crack. Furthermore, the existing bridge was not designed to any seismic standards which present a major concern given the bridge’s location in the seismically active Pacific Northwest.
The new Sellwood Bridge will be a deck arch structure with three arches supporting the deck of the main river spans and is designed to the latest seismic standards. It will feature two 12-ft travel lanes, two-12 ft shared use sidewalks, and two 6.5-ft bike lane/emergency shoulders. Multnomah County is using the existing bridge truss on temporary pile foundations as a detour to save time and money during construction with minimal impact to traffic. According to www.cyclonebuildings.com, the original bridge truss was shifted on January 19, 2013. Complicating the move was the enormity of the bridge, an 1100-ft single truss weighing 3400 tons. In addition to the size and weight of the span, old age and its curved alignment added to the technical challenges. The impressive move took only 14 hours. The detour bridge is currently fully operational and will continue to carry traffic until the summer of 2015 when the new bridge is scheduled to open.
DBA played key roles in the design and construction of the main arch piers. As part of the VE Design, DBA assumed engineering responsibility for the 10-ft diameter drilled shafts supporting Piers 4, 5, and 6 (4 & 5 being in the river and 6 on the eastern shore). The lengths of these shafts ranged from 81 ft to 225 ft through a number of subsurface conditions which posed many challenges to construction. Subsurface conditions ranged from large loose cobbles/gravel (Catastrophic Flood Deposits) to cemented cobbles and gravel (Troutdale Formation), to very hard intact basalt bedrock. Due to the challenging geologic conditions and variability of these conditions across the site, DBA implemented an observational method in which the final shaft length determination was made on the basis of our on-site observations in relation to a set of predefined criteria. This approach provided the necessary flexibility to efficiently confront different subsurface conditions in a timely manner. Drilling subcontractor Malcolm Drilling successfully completed construction of the last of these shafts in mid-October 2013.
You can learn more about the bridge and the project at Multnomah County’s website, SellwoodBridge.org. The website has current field work updates, photo gallery, history of the project, and a live construction camera with daily, weekly, and monthly time-lapse videos. There is also a time-lapse of the moving of the old truss.
As reported by the Minneapolis Star Tribune, Case Foundation recently finished constructing 40 drilled shafts at the St Croix River Crossing Project. Since early June, Case has been working at a feverish pace to construct the drilled shaft foundations for the new extradosed bridge between Minnesota and Wisconsin. As of November 8th, all of the drilled shafts are officially complete. General contractor Kramer is working to finish the pier footings and support tower bases by early 2014. Soon, the joint venture of Lunda and Ames will begin construction of the $380 million bridge superstructure.
As MnDOT’s foundation consultant for the project, DBA has been on site during much of the foundation construction over the past five months. Some pictures taken during this time, along with several pictures from MnDOT are available for viewing on our Picasa Page. More pictures and information can be found on the project website and Facebook Page, and the project can be viewed live via webcam. Previous DBA blog posts about the main project and the predesign load test program can be found here.
DBA is pleased to wrap up its role on the St Croix Crossing Project with a very positive outlook. The drilled shaft construction proceeded on schedule and as planned without unexpected challenges, and our strong client relationships with MnDOT continued to grow stronger. It was also nice to see familar faces from Case, Braun Intertec, and Parsons Transportation Group, many of whom we worked with us at Hastings. We very much look forward to working with these partners again in the future!
History was made on Sept. 7, 2013when state and local officials cut the ribbon on the new Hurricane Deck Bridge during a ceremony held in the center of the new structure. The bridge officially opened to traffic in the late evening on Monday, Sept. 9. The original bridge is now closed and will be prepared for demolition during the remainder of 2013. Final demolition will take place in the spring of 2014.
The W. 7th Street bridge is a gateway between downtown Fort Worth and its cultural district. TxDOT designed the bridge with six arch spans across the Trinity River to improve safety, pedestrian access and add to the architectural redevelopment under way in this corridor. The project will widen and reconstruct the four-lane bridge with 10-foot sidewalks. It is the world’s first pre-cast network arch bridge.
ENR had an article in early June about the unique bridge (requires subscription to ENR):
Looking north towards Hastings as traffic travels on both bridges
Looking west from the Hastings’ river bank
I had the unique opportunity to be among the first people to cross the new Hastings bridge and among the last to cross the old Hastings bridge, during the short period of time when the two bridges were simultaneously carrying traffic.
Yesterday evening, Monday, June 3rd, crews shifted southbound traffic onto the new bridge for the first time. This evening, the old bridge will be closed to traffic for good as crews shift northbound traffic onto the new bridge. According to the Minneapolis Star Tribune, there will be a funeral service of sorts for the 1950’s era truss bridge tonight, complete with a bagpiper and hearse.
Being just up the road for the St. Croix Bridge Project, I took the opportunity to travel across both bridges today and take a few pictures like the ones above. It is not every day that we, as foundation designers, get a chance to see this stage of a project. Luckily, I was in the right place at the right time.
Specialists in Deep Foundation Design, Construction, and Testing and Slope Stability Problems