An engineer working on the Miami university bridge warned of cracks in the structure, two days before it collapsed killing at least six people.
Denney Pate, lead bridge engineer for contractor FIGG, left a voicemail with the Florida transport department on Tuesday.
He warned of "cracking" but also said there was no concern "from a safety perspective".
Department employees did not hear the message until after the bridge fell.
The Florida International University (FIU) concrete bridge collapsed on to a motorway, crushing at least eight vehicles driving beneath.
The number of victims is thought likely to rise as workers clear the rubble from the 862-tonne structure, which was erected days before as a walkway for university students.
'Obviously the cracking is not good'
Mr Pate attempted to call an employee on a landline at the Florida Department of Transportation (FDOT) on Tuesday.
However, the employee was away on assignment and did not hear the message until Friday.
The department has released a transcript of the message in which Mr Pate speaks of cracking at the north end of the bridge, saying "obviously some repairs or whatever will have to be done".
However, he said "from a safety perspective we don't see that there's any issue... although obviously the cracking is not good".
Florida Senator Marco Rubio tweeted that workers had been tightening cables supporting the bridge at the time it collapsed.
The National Transportation Safety Board (NTSB) investigator Robert Accetta said cracks in the structure did "not necessarily mean that it is unsafe".
The bridge was put up last Saturday in just six hours, and the university hailed the "first of its kind" bridge online.
FIGG Engineering was behind the bridge project, along with Munilla Construction company (MCM), a family-owned contractor.
MCM tweeted "thoughts and prayers" for those affected by the tragedy.
Both firms said they would co-operate with investigators.
(BBC)