Urgent repairs are needed to Ballagawne Bridge near Kirk Michael.
The Department of Transport has discovered corrosion on the iron girders which support the structure, on the Kirk Michel to Peel Road.
No major work has been carried out on the bridge since it was built, to carry traffic over the old Kirk Michel to St John's railway line.
Extra supports will be installed on either side over the next two weeks, with traffic directed over the centre of the bridge to avoid the weakened area.
Allinson: Government responding to calls over MiCard system
Previous plans to discontinue service have come under fire this week
Mountain Road closure extended by additional 24 hours
The road has been closed since Wednesday
Number of primary school pupils choosing school meals down nearly 20%
Data throughout the year shows more students taking up packed lunch
Tynwald backs major overhaul of jury eligibility rules
Order removes most automatic exemptions and widens the Island's pool of potential jurors
Peel Commissioners hopes for improved communication with new trader's association
Member Stuart Hardingham believes the relationship is a 'two way street'