Engineering review of $1B, FIGG-backed Houston bridge identifies design issues

Dive Brief:

An independent consultant has identified 21 areas of "significant concern" as the result of an analysis and structural check of the $1 billion Ship Channel Bridge in Houston and has recommended steps the design team, which includes FIGG Bridge Engineers Inc., should take to resolve the issues. COWI made its report to the Harris County Toll Road Authority's (HCTRA) Commissioners Court.
Some of COWI North America Ltd.'s major concerns are an "inappropriate" pile load-displacement relationship; unreliable wind loading used for the design and inadequate estimates for pylon foundation settlement and tilt. The findings also claim that traffic load on the southbound structure was not considered when performing an analysis for the northbound structure's erection; pile geotechnical capacities at the foundations do not meet the project's requirements; and pylon pile cap structures do not meet strength requirements.
COWI's recommendations to the HCTRA are that the project team make revisions to the portions of the bridge that are not yet constructed; make corrections as necessary to the portions of the bridge already built; decide whether to leave already constructed yet nonconforming portions of the project as-is; and request the bridge's designer to validate the bridge design given the information in the report.

Dive Insight:

HNTB is providing construction management services for the project, and the joint venture of Zachry Construction Corp. and Traylor Bros. Inc. is building the bridge. FIGG is the engineer of record.

The HCTRA stopped construction on the main pylons of the cable-stayed portion of the bridge in January and requested that FIGG perform a redesign related to the curved portion of the pylon legs.

In response to COWI's report, FIGG said, "Reviews are common in the bridge engineering profession," FIGG said, "and it is typical for engineering analyses from two companies to have differences. It was fully expected that there would be some comments to address. FIGG looks forward to the next stage of this process where all the engineering companies on the design team will be able to collaborate in reviewing any comments.

"We are pleased to work with HCTRA, their review consultant, the other design engineering companies, and the contractor to provide a final bridge that is a point of function and pride within the community."

Other concerns raised in the COWI report include:

Pylon curved legs regions don't have the required capacity, and pylon leg cross-tie arrangements aren't up to AASHTO-LRFD (American Association of State Highway and Transportation Officials- Load and Resistance Factor Design) requirements.
Certain pylon legs need additional restraining reinforcing.
Reinforcing at lower pylon leg access door openings, in the pylon legs at transition zones from hollow to solid legs and adjacent to upper diaphragms and at the connection of the pylon leg tops does not meet project requirements.
Shear reinforcing in the bridge superstructure's edge beams and stay cable slip resistance in cradles in pylons do not meet requirements.
Settlement data may not be accurate.

The Texas DOT demanded that contractor Flatiron/Dragados LLC remove FIGG from the Corpus Christi Harbor Bridge project, and, according to KIII-TV, the search for a new bridge engineer began last month. The TxDOT said that FIGG downplayed its role in the deadly 2018 Florida International University pedestrian bridge collapse.