Significant disruption to rail travel is expected due to strike action by conductors from this Sunday.
It comes after members of the RMT rail union voted to take action in a ballot earlier this month over calls for overtime payment increases.
The union said the strikes would take place each Sunday until May 2, with the possibility of further action if no agreement is reached with ScotRail.
A number of key routes will be affected warn ScotRail, with limited bus services to University Hospital Hairmyres in East Kilbride for key workers.
It posted on its website: "It means that services will be cancelled on several key routes and will have a significant impact on people who need to travel."
In addition to the Sunday strikes, the RMT has instructed its members not to work on any rest days or undertake "higher grade duties" from 00:01 on Friday until further notice.
RMT general secretary Mick Cash said: "We have made it clear that we will not allow ScotRail to divide the workforce and are demanding that ScotRail do what is fair and honour an enhanced rate for rest-day working for all grades."
ScotRail head of conductors Graham Ralston said: "We will do everything we can to minimise the consequences of this action, but key workers will be adversely affected.
"Inevitably, many will have to find alternative and much less convenient ways to get to work to perform their life-saving duties."
Meanwhile, the RMT is balloting ScotRail ticket examiners for strike action over the same issue.
The ballot runs until April 8.
