Harbor Bridge Design Solution Work Continues


Officials from the Texas Department of Transportation recently provided an update on the new Harbor Bridge project, noting that four of the five design concerns have been resolved. Project Developer Flatiron/Dragados also noted that the project is expected to exceed its almost $1 billion budget.

Discussions between TxDOT engineers, IBT engineers and the project’s engineer of record, Arup-CFC, are ongoing, said Valente Olivarez Jr., TxDOT's Corpus Christi District engineer, with final solutions anticipated in the coming weeks.

Project Background

Beginning in 2015, joint venture Flatiron/Dragados LLC was chosen by TxDOT for the design-build contract for the new Harbor Bridge.

The new bridge is slated to carry U.S. Route 181 across the Corpus Christi Ship Channel off Corpus Christi Bay, replacing the current Harbor Bridge, a through arch bridge that was built in 1959. Once completed, the bridge will be the longest cable-stayed bridge in the United States. According to TxDOT at the time, the total cost of the project—including the construction of the new bridge and the demolition of the current one—would be approximately $802.9 million.

In March 2017, construction activities began on the project, and by February 2019, crews had completed concrete placement on the first lift of the south tower.

The following month, Flatiron/Dragados announced that the project would likely not meet its April 2020 completion deadline. However, the first span had been put into place on the north side of the ship channel, marking a significant milestone. Company officials attributed the delay to weather conditions and permitting issues.

In November 2019, TxDOT declared the suspension of design work for the Harbor Bridge. The announcement arrived after the National Transportation Safety Board released its findings related to the FIU bridge collapse in October, revealing that the probable cause was related to load and capacity calculation errors made by the Harbor Bridge project’s designer, FIGG Bridge Engineers Inc.

Consequently, at the beginning of 2020, TxDOT requested that Flatiron/Dragados LLC replace FIGG. FIGG had overseen designs for the Harbor Bridge’s main spans—which are included in the cable-supported section of the bridge that will cross the Corpus Christi Ship Channel.

Due to the suspension and previous delays, the Harbor project’s original completion date—slated for 2021—was pushed back to early 2023, increasing the project’s total to $930 million.

In July of last year, TxDOT halted construction on the new span due to safety concerns, only impacting construction regarding the new cable-stayed portion of the project. In a letter released to the public, which dated the same day construction was halted, TxDOT wrote to Flatiron/Dragados Project Manager Keith Armstrong in response to the upcoming installation of delta frames and the suspension of work over safety issues.

Earlier in the year, the department had consulted bridge design and engineering service International Bridge Technologies to independently review the designs. The company concluded that there are “significant design flaws that raise serious concerns about the safety of the New Harbor Bridge.”

While IBT found “numerous technical findings and observations” to be addressed, the department explained that the five areas of primary concern include:

  • Inadequate capacity of the pylon drilled shafts;
  • Deficiencies in footing caps that led IBT to report that the bridge would collapse under certain load conditions;
  • Delta frame design defects, primarily related to the connections between the delta frames and the adjacent precast box units;
  • Significant uplift at the intermediate piers; and
  • Excessive torsion and other stresses related to crane placement during construction.

The letter also added that Flatiron/Dragados, as well as its Engineer of Record Arup-CFC, had failed to “adequately address the nonconforming design,” continuing to deny any problems with the design “despite ample evidence to the contrary.

Flatiron/Dragados also sent a letter to TxDOT, acknowledging full responsibility for a safe design and construction of a safe bridge. The contractor committed “to do whatever needs to be done, including any changes to our teams’ culture as necessary, to assure that the FDLLC and the TxDOT teams are able to work collaboratively toward the successful conclusion of this project.”

As part of the commitment, Flatiron/Dragados would provide design and install the items of work to resolve the concerns listed in the report at its expense.

On Aug. 30, Armstrong provided a follow-up letter outlining a preliminary schedule and action plan regarding the bridge’s design concerns. The plan defines the following proposed design changes:

  • Extend the footings adjacent to the tower legs and add additional drilled shafts to each tower;
  • Add longitudinal and transverse reinforcement to the top of the in-situ concrete joint between the delta frame and adjacent precast segment and make continuous into both precast units;
  • Modify the bridge design to prevent bearing decompression from occurring at strength-limit state;
  • Establish limiting values of tension strain in the bottom flange of the superstructure above the temporary pier and monitor during construction; and
  • Restart meetings and dialogue to resolve any other items of concern.

Then, in November, work partially resumed on the bridge as a design fix for the delta frames was approved by the project’s engineer of record. The Caller Times reports that, as of October, the north approach was 81% complete and the south approach was 87% complete. Roadworks for the north and south approaches were 91% and 84% complete, respectively, and utilities were at 95%.

According to FDLLC, all of the concrete approach segments have been completed. The main span segment casting was reportedly 59% finished, with the delta frame casting at 77% completion.

Reports indicated that deficiencies in the bridge's main span design, including elements of the bridge's foundation and stability in certain wind conditions, and the specific crane placements during the construction process of the main span, had yet to be addressed at the time.

Additionally, the project was pushed back once again, with a tentative completion date in 2025. An official timeline was expected to be provided when design concerns were resolved.

Last month, it was reported that the foundation footing is going up for the bridge to support the structure of the tower that will hold the cables and the bridge deck.

Routine painting on the existing Harbor Bridge also began earlier in February, with work including coating steel truss members above and below the bridge deck. Weather permitting, the painting project is expected to be completed this summer.

Design Solutions, Progress

Work is reportedly underway on the first three issues following their accepted design solutions. The inadequate capacity of the pylon drilled shafts will be resolved by adding more drilled shafts at foundation extensions at north and south pylons.

For the deficiencies in footing caps, related to proximity of pylons to edge of caps, Flatiron/Dragados will add footing extensions to increase foundation capacity and edge distance for the north and south pylons. These footing extensions will be supported by the supplemental drilled shafts added as part of Item 1.

The delta frame design defects will see capacity increases for the connection between the delta frames and adjacent precast concrete units. This will involve roughening the concrete surfaces and adding rebar that crosses the interface.

However, the uplift at intermediate piers concern is reportedly unresolved, and work has not started. The Caller Times reports that Flatiron/Dragados, Arup-CFC, TxDOT, and IBT are exchanging information and anticipate acceptance of a design solution in the next few weeks. This portion of the bridge has not yet been constructed; therefore, no field corrections are needed.

The fifth concern regarding excessive torsion and other stresses related to crane placement during construction has been addressed by revising the erection plan. Flatiron/Dragados will reportedly incorporate counterweights to account for any potential high wind events as the construction of the main spans nears completion.

Flatiron/Dragados expects the bridge to be completed and opened to traffic sometime in the first half of 2025. This timeline is reportedly five years after its initial completion date.

The project is anticipated to have cost overruns past its total budget of about $930 million. However, reports indicate that TxDOT has promised that local government entities will not be required to front these delay-associated costs.


Tagged categories: Bridges; Bridges; Contractors; Contracts; Department of Transportation (DOT); Design; Government contracts; Health & Safety; NA; North America; Ongoing projects; Program/Project Management; Safety

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