Investigators have criticised Network Rail over an accident at a level crossing with no barriers that killed three people.
Driver Angus MacKay, his wife Margaret, who were both 81 and from Inverness, and Mr MacKay's brother Donald, 66, from Latheron, Caithness, were killed in September's accident at Halkirk in Caithness.
The Rail Accident Investigation Branch says the organisation failed to understand the dangers at the crossing in Halkirk in Caithness despite a series of previous incidents there.
Mr MacKay's eyesight was considered the primary cause of the accident.
The report makes six recommendations, including changes in the design of level crossings to increase the visibility of warning lights. It has also asked Network Rail to look again at whether the crossing should be upgraded.
In September 2009 a train and a car hit one another at the level crossing in Caithness, killing all three occupants of the car. There were no injuries to anybody on the train which was not derailed.
The report said that the most likely cause of the smash was that the car driver did not see and react to the flashing road traffic light signals because his eyesight was sub-standard.
An underlying factor was that Network Rail did not properly understand the risk at Halkirk level crossing because it had not taken the previous accident record into account.
Had it done so, the level of risk might have justified more costly risk reduction measures, and risk reduction measures that had been identified might have been implemented more quickly and before the accident occurred.
The report has identified six areas which Network Rail must improve on.These include a risk assessment of the level crossing and the maintenance of the backboards of the road traffic light signals.
The sole purpose of a Rail Accident Investigation Branch investigation is to prevent future accidents and incidents and improve railway safety.