The Tees Transporter Bridge has been closed to allow essential repairs and maintenance to be carried out.
During a routine inspection it was established that further structural work is required to the 107-year-old North East icon.
A detailed assessment is currently being undertaken, but the Bridge is likely to remain closed for several weeks.
The Transporter lift and Visitor Centre will also remain closed while the work is carried out. Further announcements will be made in due course.
Councillor Dennis McCabe, Middlesbrough Council's Executive member for Environment, said: "The Transporter provides a much loved service all year round, but a structure of its age needs attention from time to time.
"We apologise for any inconvenience, and hope to have the Bridge open again as soon as the work is complete."