Passengers are suffering “substantial inconvenience” from faults plaguing Midlothian’s only railway, with disruption nearly every day in April.
A log of incidents shows more than 80 trains have been cancelled or delayed on the Borders line since March 31.
They include a range of faults to the signalling system, which was installed during construction of the £350 million Edinburgh to Tweedbank line.
One of the latest such incidents led to nearly half the trains on the route being cancelled or delayed. Other difficulties include “crewing issues” – staff shortages – and trains breaking down.
The Campaign for Borders Rail (CBR), which compiled the log, said passengers were further disrupted by delayed trains not stopping at some of the eight intermediate stations to make up time.
The problems follow significant overcrowding and delays after the line opened, with ScotRail forced to add extra carriages to many services to cope with demand.
CBR vice-chairman Robert Drysdale said: “In six months, the Borders Railway has transformed travel opportunities in the region and has been quickly embraced by local people, which is why the failures during April are so unwelcome and unfortunate.
“A brand new railway should not have trains and signals which fail, causing substantial inconvenience to affected travellers.
“The good reputation of the railway, which had been improving since the early teething problems, is now being damaged.
“It’s important that Network Rail and ScotRail get to the root of these problems urgently, and the refurbishment and replacement of old trains must be accelerated.”
The ScotRail Alliance, which includes track owner Network Rail, was unable to say how many trains had arrived “on time” – within a minute of schedule – in April.
The latest published figure for the route, for March 6-31, was 43.5 per cent.
An alliance spokeswoman said: “Train services on the Borders Railway generally ran well during the first two weeks of April, with around 94 per cent of services arriving within five minutes of their scheduled time. In week three in April, it was 79.3 per cent.
“Then three issues affected services – a train fault resulted in a service being cancelled at Gorebridge, and two separate signalling issues caused delays and cancellations later in the week. We made every effort to return services to normal as soon as possible.”
Network Rail said there had been a range of faults including to fibre optic cables, train axle counters and track circuits.