Train commuters were told to expect delays in February 1979.
Delays on the Larne line were expected to last for a number of weeks as work was being carried out near Whitehead.
Most of the delays were going to be at peak times when trains could be running up to 15 minutes late.
At off-peak times, delays were not expected.
The problem had been caused by subsidence of the sea wall.
This meant that single line services were going to be in operation until the repair work was completed.
A spokesman from Northern Ireland Railways said: “The work should last about a fortnight. As soon as it is completed, we will be back to normal.”