Work is due to take place in a 10-day period in August on the bridge situated near Aylesbury, meaning the section between Aylesbury and Prince Risborough will be closed between Monday 7 and Friday 18 August.
The damaged culvert has caused several short-term closures of the line including twice in March and April with Network Rail completing a temporary fix including installing monitoring equipment but the disruption on the line has now prompted Network Rail to act.
The culvert in question is a rare example where the train line was laid over the existing structure.
Immediately after the work has been carried out by Network Rail, HS2 will be carrying out works on the stretch of track.
HS2 and Network Rail will work in partnership to move and replace more than a mile of track, replacing and fitting signalling equipment south of Aylesbury to allow HS2 to pass beneath the existing railway.
It is expected these works will take place from 19 August until 30 October.
Jacqueline Dey, Chiltern Railways' operators director, said: "The damaged culvert has led to numerous short-notice cancellations this year, and we are pleased that a permanent fix will be in place before the end of the summer.
“We know that this is a significant, long-term closure, but we are confident that the railway between Princes Risborough and Aylesbury will be more reliable as a result of these important works.
“We will be working with industry partners to keep residents informed before and throughout the closure, and thank customers for their patience while these works are completed."
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