A number of services yesterday and today have been cancelled or reduced, although ScotRail has claimed that 76 per cent of routes will operate as normal.
The industrial action is over the union’s concerns about driver-only operation trains, when the driver is asked to close the train’s doors at stations, instead of a conductor.
Union members believes the absence of a dedicated guard makes trains less safe.
A man fell under a moving train while trying to board at Dumbarton East rail station in May.
The train was a driver-only operated service. The 43-year-old man was left with “life-changing” injuries and underwent surgery after falling on to the tracks.
Last week Southern Rail users staged mass protests and threatened to withhold payments for train tickets due to ongoing cancellations and delays on the Southern network. Rail passenger groups believe that Scottish commuters could follow suit.
Campaign group Railfuture’s spokesman Bruce Williamson said: “There’s no doubt that ScotRail passengers are growing more and more frustrated.
“Everyone has a limit: these strikes and disruptions cause considerable upset to commuters’ lives.
“Passengers want a reliable railway, and unless rail bosses sort themselves out we could be in for a summer of discontent.”
This weekend’s strike comes as the 145th Open Championship takes place at Royal Troon in South Ayrshire.
Transport minister Humza Yousaf said last week: “These rail strikes are continuing to inconvenience people right across the country.
“It’s particularly disappointing that they are falling on the week of the Open Championship, which is one of the highlights of Scotland’s sporting calendar.
“However, rail passengers should note that travel planning is well advanced, with ScotRail offering an enhanced timetable above the regular provision.”
Phil Verster, the firm’s managing director, said: “The RMT have refused point-blank to talk to us about how we modernise and improve Scotland’s railway.
“Instead, they have hidden behind a national policy that says that nothing must ever change.
“Tens of thousands of our customers will be disrupted and hundreds of our own people will be hit financially as a result of their intransigence.”
A recent parliamentary question revealed that 214 out of 346 Scottish stations are unstaffed. As a result, the RMT union’s general secretary Mick Cash claims that disabled and vulnerable passengers will suffer if driver-only operation is extended in Scotland.
He added: “It is clear from their failure to intervene that the Scottish Government are committed to introducing driver-only trains, a practice that RMT views as unsafe and inherently dangerous. RMT has been engaging with the public over the last eight weeks and we have the overwhelming support of the Scottish people who want to see a safety-critical guard on our services.”