UNION officials preparing for a seven day strike of staff who operate Cross Keys swing bridge at Sutton Bridge said they “fully expect disruption to both river and road traffic.”

The bridge daily takes thousands of vehicles across the Norfolk border into Lincolnshire and any disruption could cause massive delays on the A17.

A Unison spokesman said, however, the strike “will be more likely to disrupt river traffic and the port at Wisbech.”

The union said they were concerned about how the bridge will operate during the strike- due to start at midnight tomorrow.

Bridge keepers go through “significant training” and unqualified operatives could compromise safety. The only people in Lincolnshire to have undertaken that training were also Unison members, said the spokesman.

The union said they be watching developments keenly after Paul Coatup, the council’s assistant director of highways, spoke of “contingency plans” to keep traffic flowing.

“There may be some inconvenience for leisure boats travelling through, but we will work hard to keep this to a minimum,” he said.

The council denies union claims that proposed changes will mean a £300 monthly drop in pay for two bridge operators and a £400 month drop for their supervisor.

Tom Street who is a bridge keeper and Unison Steward said: “We don’t just open the bridge- 90 per cent of our time is maintaining it to a high and reliable standard.

“There are about 30 commercial ships a year into Wisbech. These ships weigh about 2500 tons, and it is vital the bridge opens for them. If one struck the bridge due to a break down then everyone will be taking the 40 mile detour through Wisbech for a long time.

“This is why maintenance and safe and reliable operation is important.”

He added: “We aren’t asking for a pay rise, we are just trying to protect what we already get.”