Four miles of track replaced between Bury St Edmunds and Ipswich as part of Network Rail's project to improve train services' reliability
National Rail also installed new sleepers and ballast – the stones that keep the track in place – during the 11 weeks of work, which was completed yesterday.
Officials said the work, which started on July 18 and was completed at weekends, was part of upgrades to improve services between Ipswich, Ely and Cambridge.
They said track, in a similar way to road surfaces, gets worn from constant use every day, so engineers carry out inspections and repairs regularly.
But over time the track becomes so worn that a full replacement is the only option to avoid speed restrictions that cause delays and cancellations.
Ellie Burrows, Network Rail’s route director for Anglia, said: “Keeping the tracks in good condition is vital to running a safe and reliable railway for our passengers and that is exactly what we’re here to do.
"This is a busy section of our network for passengers and freight and this work will reduce the number of delays and cancellations caused by track faults.”