An investigation into the deaths of two SMRT trainee staff members on March 22 has found that the incident could have been avoided if safety measures had been put in place.
In a statement, the rail operator said that before a work team is allowed onto the track, a speed limit must be set to ensure that no train enters the track and watchmen must be deployed to look out for approaching trains and provide early warning to the work team.
SMRT said that an accident review panel formed determined that this "vital safety protection measure was not applied and that the effectiveness of such protection before entry into the work site was no ensure as required under existing procedure".
This directly caused the accident which led to the deaths of Nasrulhudin Najumudin, 22, and Muhammad Asyraf Ahmad Buhari, 24, who were part of a 15-man team who went down to the track to investigate a reported alarm from a conditioning monitoring device for signalling equipment.
The incident, which took place near Pasir Ris MRT station led to the suspension of trains services on the East-West Line between Tanah Merah and Pasir Ris stations for more than two hours.
Explaining what happened that day, SMRT said that the 15-man joint engineering team was tasked to examine the device which had earlier registered a warning of a possible fault that could affect train services.
Engineering staff are authorised to access the track to investigate fault, on average, about two to three times a day on the North-South and East-West Lines, said SMRT.
As the men made their way towards the device in a single file along the maintenance walkway, they stepped onto the track - led by their supervisor - before the safety measures could be implemented.
SMRT said: "The supervisor narrowly avoided being by the oncoming train, but Nasrulhudin and Muhammad Asyraf, who were second and third in line, were unable to react in time."
The statement said: "SMRT deeply regrets that the failure to apply a vital safety procedure led to the tragic accident."
Other factors which been identified for improvement include track access management controls, communication protocols and track vigilance by various parties. Aside from taking immediate steps to strengthen its procedures and supervision, SMRT said it is comprehensively reviewing all its safety structures, processes and compliance issues.