The decision to scrap tolls on the Forth and Tay bridges has been attacked by the Transport and General Workers Union due to concerns over job losses.
The union fears for the future of jobs if tolls are scrapped.
First Minister Alex Salmond set out plans to axe tolls on both road bridges last week.
However, the T&G section of Unite claim the move will leave 175 of their members facing an uncertain future.
The union, who represent toll collectors and maintenance staff, will meet ministers to discuss the issue.
The union's regional industrial organiser, Sandy Smart said that while the policy may have proved a vote winner for the SNP, it spelled unease among union members.
He expressed fears that jobs would be privatised and that current agreements on pay, terms, conditions and pensions would be under threat.
He said: "This is a very worrying time for all concerned.
"Axing the tolls has an appeal to the voters but we fear this has not been thought through.
"Not only are the toll collectors' jobs at risk, without the revenue from the tolls who will do the maintenance and engineering work and, importantly, who will pay for it?"
Union leaders have meetings planned with Scottish government officials as well as politicians to discuss the issues and concerns.
First Minister Alex Salmond said he intended to scrap tolls on the Tay and Forth road bridges as part of his programme for running Scotland.
The SNP, which has branded the charges as "unacceptable and unfair", promised to introduce a bill to abolish them within 100 days of taking office.
A spokesman for the campaign group, the National Alliance Against Tolls Scotland (Naats), said: "To suggest that the bridges can not be maintained without tolls is a nonsense.
"The executive already maintains 3,500 kilometres of other roads and road bridges. It should be able to handle two more bridges."