Points failure led to Dingwall train derailment
A points failure and problems with a system designed to warn train drivers led to a derailment near Dingwall, according to a report.
None of the 60 passengers, the driver or an attendant were badly injured in the incident in January this year.
The Rail Accident Investigation Branch (RAIB) said an indicator failed to warn the driver of problems with the points.
The points had not set properly and the driver reached them at twice the speed permitted, the RAIB report said.
One woman on the 1715 GMT service from Inverness to Ardgay was taken to hospital as a precaution following the derailment south of Dingwall.
The RAIB said in a bulletin report on the accident that there had been previous failings at the points following their replacement several days earlier.
On the day of the accident, the unreliable operation of the points had been noted but not fully rectified.
The RAIB said that had the driver been warned of the problem he is likely to have approached Dingwall station cautiously and seen that the points set indicator (PSI) was not illuminated.
The stretch of railway line was closed for three days while it was repaired.