ScotRail has failed to improve its performance over the past month because of two major disruption incidents in Edinburgh and Glasgow.
Official figures to be published next week show punctuality was unchanged in the year to last Saturday, compared to the position a month ago, The Scotsman has learned.
The “moving annual average” figure of 89.8 per cent is 0.5 percentage points below the acceptable level, and comes despite an improvement plan being ordered when the threshold was breached in September.
The ScotRail Alliance, which includes track owner Network Rail, said the plan had led to some punctuality improvements.
However, these have been cancelled out by the huge disruption caused by a train breaking down near Princes Street Gardens in Edinburgh on 17 November, and overhead lines being damaged near the Kelvin Hall in Glasgow five days later.
The incidents cut punctuality for the four-week period to 10 December by 0.9 points to 83.7 per cent, with the Edinburgh breakdown alone leading to the cancellation of 225 trains – nearly one in ten that day.
The figure for the period was 0.2 points up on the same period last year, but 2.4 points down on the previous period, in October-November, when the weather was better.
Industry comparisons are made between the same period each year to take into account seasonal weather which can hit performance, such as freezing temperatures, heavy rain and strong winds.
ScotRail Alliance managing director Phil Verster said: “This was an extremely challenging period.
“As well as having some very low temperatures to contend with, we also saw two significant incidents which caused widespread disruption on the network.”
Mr Verster said the bad weather which hit the railways may not have been noticed by passengers, such as early morning temperatures dipping to -10C, freezing sets of points. He said strong winds could damage overhead lines, or force trains to slow down, which had a knock-on effect on punctuality.
Opposition parties said the service was still not up to scratch.
North East Scottish Conservative MSP Liam Kerr said: “Every day, we see more delays, disruption and cancellations on our rail network, and passengers are calling out for significant improvements.
“While these statistics show a slight increase in performance, ScotRail are still not providing the service that commuters need and deserve.”
Scottish Labour transport spokesman Neil Bibby said: “The reality, no matter how much ScotRail try to spin it, is that [ScotRail operator] Abellio is still not hitting targets and we have seen three months of declining performance since SNP transport minister Humza Yousaf agreed an improvement plan.”
A Transport Scotland spokesman said: “We are confident ScotRail’s performance can and will improve further.
“However, given it is widely acknowledged winter can bring its own challenges, we must recognise disruption can and will happen.”