Suspension cables on the Forth Road Bridge may have to be replaced if ongoing corrosion cannot be stopped.
Corrosion has been found inside Forth Road Bridge cables
The Forth Estuary Transport Authority (Feta) is set to award a contract for a £1.5m feasibility study into cable replacement or augmentation.
It is hoped that the work will not be necessary and a dehumidifying system will successfully dry the cables out.
However, a spokesman said there were no guarantees and other options had to be considered.
Barry Colford, Feta depute general manager, said: "We're commissioning this study in case we can't stop the corrosion.
"This study will tell us if it is feasible to replace or augment the main cables, should this become necessary.
"Of critical importance is the extent of the traffic restrictions that would be required, and the effects of those restrictions on the adjacent road network."
The full results of the study, by consulting engineers WA Fairhurst & Partners, will report in 18 months time.
Feta has estimated that the bridge may have to close to heavy vehicles in 2014 if the condition of the main cables continues to deteriorate.