The discovery of an ancient bylaw means the Orwell Bridge will be closed every Wednesday morning to allow local livestock to cross, it has been revealed.
Police say the three-hour closure is likely to cause traffic chaos in and around Ipswich every week, but the move is unavoidable as they must enforce the law.
Local farmers unearthed an old manuscript at the county records office, dated from 1847, that confirms cattle have “roighte of waye oer the Orwell stream” should a crossing ever be built.
It means at least three farmers who have land on both banks of the river can now exercise their right to move cows and sheep across the huge bridge to fresh pastures.
Suffolk county highways chiefs have called on County Hall lawyers to draw up urgent plans to get the bylaw quashed.
A spokesman said: “When this ancient manuscript was drawn up, it was intended to relate to area in old Ipswich where the river is only 20 feet or so wide. It would have made sense in those days for cattle to be able to cross any wooden structure on Wednesday mornings – market day.
“But the document leaves the interpretation of what makes a ‘crossing’ open to debate. For now, local farmers have shown they can use the Orwell Bridge as it is quite clearly a crossing over the River Orwell.
“We have to go along with it and close the bridge – although we doubt any farmers would actually dare use the facility.
“It would be quicker for them to load the animals into trailers and simply drive them across to the fields on the other side.”
For now, motorists are advised to avoid the crossing next Wednesday morning.
Council chiefs are confident the council’s highways committee will revoke the bylaw in time for the following Wednesday (August 23) – although they cannot guarantee councillors will vote for the measure.
Driver Diana Majdalani said she did not mind sitting in her car at a police roadblock waiting for the animals to cross.
“It would make for a rather marvelous sight,” she said, adding: “and they were on this earth before cars and lorries anyway.”