Analysis of punctuality figures by rail campaigners Bill Jamieson and David Spaven found that the Borders Railway has “seriously underperformed” owing to the number of trains delayed or cancelled.
The Borders Rail Monitor report found that in 45 weeks out of 52 since October 2015 the service failed to meet ScotRail’s target of 92.5 per cent of trains arriving within five minutes of schedule.
Services on the line are operated by Abellio.
At Tweedbank station, the proportion of trains arriving on time - within a minute of schedule - reached a maximum of just 66.2 per cent across any one week, while the figure for Edinburgh Waverley station never exceeded 49.8%.
The authors claim that “much of the responsibility” rests with Transport Scotland and the Scottish Government for their poor infrastructure choices.
They note that less than ten miles of the line has double track and described the Class 158 units used on the route - which has steep gradients and multiple stops - as “the least reliable diesel units in Scotland”.
The report concluded: “The evidence to date suggests that it is extremely difficult to consistently operate the Borders Railway to timetable.”
A number of short, medium and long-term measures to improve performance were recommended by the authors, including introducing more reliable trains, laying double track at the Portobello Junction “pinch point” on the east coast main line (ECML) and increasing capacity on the congested ECML section from Portobello Junction to Waverley station.
The study was based on analysis of figures on the Realtime Trains website.
A spokeswoman for ScotRail said: “Borders Railway has been an extraordinary success.
“We are now providing people with an alternative way of travelling to work, to visit friends and family and to use for leisure.
“There have been some challenges and we’re determined to find the solutions that overcome them and see even more customers travelling on the line in year two and beyond.”
More than one million passenger journeys were made on the Borders Railway since it was officially opened by the Queen in September 2015.
The link re-established part of the former Waverley line, which fell victim to the notorious Beeching cuts in the 1960s.