A major bridge carrying traffic in and out of Lincolnshire could close due to strike action.
The Cross Keys Bridge, which carries the A17 over the River Nene, could be brought to a standstill if workers decide to carry out industrial action in a row about pay.
Trade union Unison is asking three members who work on the swing bridge if they are in favour of action because of an allowance being cut.
The union says a range of industrial action measures are on the table including strikes.
It is claimed that the weekend pay allowance has been cut by Lincolnshire County Council without the agreement of staff or Unison.
The union says members have seen their take-home pay cut by around 13.5 per cent as a result.
"The council want to take away their weekend allowances which will then see their take-home pay slashed," said Gavyn Graham, assistant branch secretary at Unison Lincolnshire.
"They have to staff the bridge 24 hours a day, seven days a week and could be called out at anytime.
"They have a basic salary of £18,500 so this cut would hit them quite hard."
The hydraulic swing bridge opened in 1897 and was originally used for both road and rail traffic.
It became a road bridge in 1965 but priority is given to river traffic.
"As well as strike action, we would consider a work to rule system," added Mr Graham.
"If we were to strike, Lincolnshire County Council would have to make a decision on whether they could keep the bridge open to traffic.
"If they did, they would have to find another way to operate the bridge.
"Due to health and safety rules, not just anybody can operate it.
"The workers have to live within a certain radius of the bridge and have budgeted for a certain salary.
"We are asking for the allowance to be reinstated or for them to go up a grade so there is not a drop in pay.
"Some of them may consider whether they would stay in their jobs so the council is playing a dangerous game."
The bridge swings open to allow river traffic to pass under it to the port of Wisbech a few times a week.
Richard Wills, director for communities for Lincolnshire County Council, said: "We're currently involved in a dispute procedure so it would be inappropriate for us to comment at this time."