Train services running between Norfolk and Suffolk have been changed because of a bridge problem.
Somerleyton swing bridge in Suffolk can currently only be opened using a temporary winch system because the central pivot mechanism is damaged.
Since the damage was detected earlier this year it has been taking longer for the bridge to open to let boats pass.
To allow the bridge to open some trains from Norwich to Lowestoft will leave five minutes later than scheduled.
Train services using the bridge were suspended for 10 days in January while temporary measures to allow periodic opening were carried out.
Engineers are now working on a more permanent solution.
Network Rail route director Andrew Munden said: "Running a 21st century railway on Edwardian infrastructure is a challenge.
"We thank boat users for their patience while we work to secure the best long-term solution for this unique structure."