The Florida Department of Transportation ordered the immediate closing of the bridge after inspectors discovered two post-tensioning tendons so badly deteriorated they had to be replaced.
For the second time in its 26-year history, the Mid-Bay Bridge was closed to all traffic in January of 2019 so that emergency repairs could be made to support tendons running beneath the structure.
The first closure, in 2000, lasted 12 days.
This year the toll bridge was completely closed to all traffic for a full week, between Jan. 8 and 15, and heavier commercial trucks were forced to take an alternate route between Niceville and Destin for a couple of months more.
The closure was among the most-viewed Northwest Florida Daily News stories of 2019.
The Florida Department of Transportation ordered the immediate closing of the bridge after inspectors discovered two post-tensioning tendons so badly deteriorated they had to be replaced, Van Fuller, the executive director of the Mid-Bay Bridge Authority told the Daily News in January.
The tendons are pre-stressed steel cables that run through the hollow midsection of the 3.6-mile bridge and help support the structure.
It was quickly determined that permanent repairs to the bridge would take months and cost the Bridge Authority between $4 and $5 million.
Fuller told the Okaloosa County Commission in February that further inspection after the initial closing revealed eight of 912 total bridge tendons had been determined to be problematic.
At the same meeting, Fuller reported the Bridge Authority and FDOT had agreed to take certain measures to help prevent another total bridge shutdown.
Monthly walk-through inspections of the bridge’s innards and annual vibration testing of all its tendons were among the preventive steps planned, Fuller said.
Designed by Tallahassee-based Figg Engineering and built by Traylor Construction of Evansville, Ind. the Mid-Bay Bridge was completed in June 1993 at a cost of $44 million.
When tendon damage was discovered beneath the structure in 2000, just seven years after it opened, then Transportation Authority Director Jim Vest was skeptical of a theory that salt water could have so quickly caused corrosion.
By the time the 2000 damage was discovered, 11 tendons had corroded to the point they had to be replaced. One had failed completely and was found lying on the ground inside the bridge.
The crisis and subsequent repair work caused the bridge to be closed for a total of 17 days and shut down for parts of eight more.
A DOT report provided in draft form in February of 2001 blamed a chemical reaction caused by air and water encased within the steel tendons "most likely since the time of construction" as the believed source of the early onset of corrosion.
The evaluation labeled the cement-like grout used by builders to seal the tendons’ steel strands "suspicious." It said there were places where poorly mixed grout created air pockets where corrosion-causing moisture built up.
"The general impression of the inspectors and investigators involved with the review of the Mid-Bay Bridge is that the grout used is of suspect quality in many areas of the bridge," the 2001 report said. "Samples taken and tested were described as soft, chalky and visibly porous."
Investigators also found evidence that polyethylene ducts used to seal tendon ends "did not meet the requirements of the construction specifications."
"This should be further investigated by the Bridge Authority," the evaluation concluded.
The Bridge Authority contemplated taking legal action against either the construction contractor or Figg Engineering to cover the $6.1 million cost of the repairs done in 2000-01. No lawsuits were ever filed.
In 2001, following an investigation sparked by the Mid-Bay Bridge incident, FDOT found grout issues on 41 other Florida bridges and sought to require state-wide grout-mixing training to help ensure new bridge construction was being done correctly.