If it's opened short term it will then become impossible to close it later.
FWIW this was my email to AC-H
Dear Mr Cole-Hamilton
I understand that you are suggesting that the Forth Road Bridge should remain open to all vehicles. Although you say that this would be temporary, I'm sure you are aware that once this is permitted, the pressure to make it a permanent arrangement would be impossible to resist, and this would be exactly the wrong approach to take.
We need, in West Edinburgh particularly, incentives to get people out of their cars and into public transport, or active travel. The routes into and out of West Edinburgh are already congested and unpleasant enough and the consequent air pollution is shortening the lives of many of your constituents today; do you really want to make that worse in the future. The proposal to use the Forth Road Bridge as a public transport corridor is sound. It should be coupled with improved public transport links to commuting destinations in Edinburgh and Fife. When people see good facilities, they will use them.
The Queensferry Crossing was never planned to provide extra capacity, it was necessary because the old bridge had deteriorated to the point where it could no longer sustain the punishment it was getting from the current traffic load. With repairs it can support a public transport function as well as providing facilities for pedestrians and bicycles.
I hope that you will change your view on this matter and truly support a sustainable Edinburgh and Fife.
Yours sincerely
ih