The council's Norwich Western Link project manager has quit, just months after the business case was submitted.
Chris Fernandez was the NWL project manager for three years before stepped down last week.
Norfolk County Council has said the departure will not result in a change to the project's timetable.
An email seen by the Local Democracy Reporting Service says that Mark Kemp, who has overseen the Great Yarmouth Third River Crossing, will step in until a permanent replacement is found.
Martin Wilby, cabinet member for highways, infrastructure and transport at Norfolk County Council, said Mr Fernandez had accepted another job.
"In his three years leading the Norwich Western Link team, Chris has overseen the project through some key milestones and I’d like to put my thanks to him on record and wish him the very best for his new position.
“We have a very capable and experienced team working on the NWL which has recently grown with Ferrovial Construction coming on board as our design and build contractor.
"No changes have been made to the project timetable.”
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