Last week Scottish Conservative transport spokesman David Davidson said he is "exasperated" by the executive's approach to the proposed crossing, after a Forth Estuary Transport Authority (FETA) report found that the Forth Road Bridge is suffering from "irreversible" corrosion (Planning, 18 November, p6).
Ministers insisted that the findings will not rush the executive into backing plans for a new crossing. They have ordered an independent review of FETA's investigation and hope that the initial findings will be ready in January.
"We have commissioned the work, which will tell us what options we have in terms of the bridge," said transport minister Tavish Scott.
He acknowledged that a new bridge is an option, but added: "No government can take a decision as important as this without proper evidence. The engineering study will tell us exactly what is going on with the cables and then FETA and Scottish ministers will have to make a decision on what to do."
FETA's report states that if no action is taken, the bridge might have to close to heavy goods vehicles in 2013. The authority supports building a £600 million crossing to carry a light railway and road vehicles.
But Davidson said: "It has been apparent for some time that the existing road bridge is suffering from chronic over-use and is in dire need of a replacement. Yet the executive seems unwilling to make any firm commitments or concede the obvious - a new bridge is required."
The Scottish National Party also supported calls for another crossing.
"If there are to be restrictions on the bridge or it has to be closed for repairs, it would be a catastrophe for eastern Scotland's economy," said nationalist MSP Bruce Crawford. "We cannot allow this to happen."