The company said the Stirling-Alloa-Kincardine route, which opened just five years ago, has been heavily used by coal trains supplying the Longannet power station in Fife.
In July, it was announced the power station may continue to operate until 2025. Network Rail said the planned work on the line, expected to cost up to £17m, would also improve its ability to withstand severe weather.
It is expected to be closed for periods throughout the next five years.
A Network Rail spokesman said: "The Stirling-Alloa-Kincardine line is a key route for coal trains travelling to Longannet and it has seen increasing levels of usage since it opened in 2008.
"That usage is also set to continue for longer with the extension of the lifetime of the power station.
"We intend to carry out a rolling programme of works to renew some sections of the line that require formation treatment to support the ongoing tonnages of coal traffic. We will also be carrying out drainage works to future-proof the route against the wetter and more severe winters we have been experiencing."