Drivers in Hull are being told to expect a year of disruption, as engineers are appointed to investigate what work needs to be done to protect a 1960s-built flyover.
The research would determine the feasibility of strengthening the Hessle Road flyover.
Hull City Council said the engineering firm would try to minimise the impact of the work on traffic.
The authority added the structure "retains sufficient loading capacity to operate safely". The flyover is currently open to all traffic, it said.
Councillor Mark Ieronimo, cabinet portfolio holder for transportation, roads and highways, said the work was about "ensuring the long-term safety and resilience of Hessle Road Flyover".
"The investigation works will provide essential information to determine the feasibility of a future strengthening programme," he said, adding it would help protect a key transport route.
The flyover was opened in 1962 and carries traffic and pedestrians over a railway line.
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