ScotRail passengers face disruption on seven lines across Scotland until December during work to electrify the main Edinburgh-Glasgow route, it announced today.
This is in addition to changes already affecting the main line and a secondary route between the cities via Shotts.
Many weekend trains will be replaced with buses or diverted, lengthening journey times,
The changes from Saturday, 22 October will also involve queuing systems at busy stations.
The ScotRail Alliance, which includes track owner Network Rail, said the improvements would make the Scottish network "rank amongst the very best”.
The pledge came as the alliance is implementing an improvement plan ordered by ministers after performance fell below par.
Lines affected include:
Some Glasgow-Aberdeen trains diverted via Cumbernauld or Fife on Sundays until 4 December.
Weekend Glasgow-Inverness trains may be diverted via Fife until 11 December, or partially replaced by buses.
Edinburgh-Inverness trains replaced by buses between Perth and Inverness on 26-27 November and Sunday 4 and 11 December.
Glasgow-Alloa trains diverted via Cumbernauld or cancelled with buses to/from Falkirk High.
Glasgow-Falkirk Grahamston weekend trains cancelled 22 October to 20 November, with replacement buses run between Cumbernauld and Falkirk Grahamston.
Glasgow-Dunblane-Perth weekend trains cancelled 22 October to 20 November with replacement buses to/from Falkirk High.
Edinburgh-Dunblane-Perth trains weekend trains cancelled 22 October to 20 November and operate only between Edinburgh and Falkirk Grahamston or Polmont at certain times of the day until 8 December, with replacement buses.
The alliance said it was working closely with Aberdeen Football Club and the Scottish Rugby Union to develop plans for Aberdeen fans travelling to the Betfred Cup semi final match at Hampden in Glasgow, and rugby fans heading for international fixtures at Murrayfield in Edinburgh.
ScotRail Alliance customer experience director Jacqueline Taggart said: “We are going through a massive period of change on Scotland’s railway.
"The work we are carrying out over the next few months will bring about a revolution in rail – with more and better trains, more services and more seats than ever before.
"However, while we transform the railway, there is inevitably going to be some impact on people’s services.
"No one likes having their journey changed. However, this short term disruption will lead to a more reliable, better rail network that will rank amongst the very best.”