According to statistics made available for the first time, 34.2 per cent of all station stops made by ScotRail services last month were reached ahead of schedule.
Twice as many – 67.8 per cent – were classed as being “on time”, or within one minute of timetable.
In addition, 94.5 per cent of trains arrived at stations within five minutes of time. But ScotRail said its official punctuality statistic, known as the public performance measure, was lower, at 87.4 per cent, because this only records arrival times at destination stations. It said delays were most likely to occur on the last part of journeys.
Early trains on Friday included the 0745 Glasgow-Edinburgh, which reached Waverley three minutes ahead of schedule. Several other trains on the main line arrived at Falkirk High early.
Elsewhere, some services from Edinburgh and Glasgow reached their Aberdeen terminus between four and seven minutes early.
ScotRail said some services arrived early because faster-accelerating new electric trains had taken over from diesels on routes such as the Edinburgh-Glasgow main line and between the two cities and Dunblane.
The timetable will be changed later this year to reflect the faster journeys.
However, ScotRail expects the proportion of early arrivals across its network to remain around 30 per cent.
Trains which arrive early at intermediate stations wait until the scheduled time before departing.
ScotRail said timetables also had extra time built in to allow for temporary speed restrictions and congestion at junctions, such as Hyndland in the west end of Glasgow.
A ScotRail spokesperson said: “We began publishing a breakdown of our performance figures in the interests of transparency.”
But Robert Samson of watchdog Transport Focus was unimpressed. “The detail in these figures gives passengers transparency but the key requirement still remains to continue to improve punctuality and reliability,” he said.
A Transport Scotland spokesperson said: “An element of early arrivals is normal as all rail timetables have in-built resilience.”