Customers are being advised to check before they travel as the next phase of the Scotland-wide rail upgrade programme gets under way.
From May 21 work will be carried out to improve the network in Central and Northern Scotland.
On those routes affected by the work, there will be changes to journeys after the end of the evening peak period.
To help customers plan ahead, the ScotRail Alliance has summarised the key changes at different times of day between now and December on a dedicated webpage at scotrail.co.uk/improvements.
Journey times will be longer and customers can expect to see queuing systems in operation at key stations.
As well as increasing the overall reliability of the rail network, the improvement work takes the next step towards introduction of new faster, longer, greener trains for Scotland – meaning more seats and shorter journey times.
The introduction of new electric trains in the central belt will lead to a revolution in rail services across Scotland, with an extra 200 daily services added, bringing in an extra 100,000 seats per day.
Jacqueline Taggart, ScotRail Alliance customer experience director said: “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.
“We are going through a massive period of change on Scotland’s railway. The work that 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. We are doing everything we can to minimise this, and to keep people moving.”