The National Transportation Safety Board (NTSB) in the US has issued three new urgent safety recommendations based on the findings of two ongoing railroad accident investigations.

NTSB’s first urgent safety recommendation to the US Federal Railroad Administration is based on the findings of an investigation regarding the collision of an Amtrak train with a CSX train, which took place earlier this month in South Carolina.

The accident resulted in two fatalities and injured several people.

The investigators found that CSX personnel had suspended the traffic control signal system on the day before the accident in order to install updated system components, which would facilitate the implementation of a positive train control (PTC) system.

“We know that signal suspensions are an unusual operating condition, used for signal maintenance, repair and installation that have the potential to increase the risk of train collisions.”

A temporary lack of signals meant that the dispatchers used track warrants to move trains throughout the work territory without any technological supervision.

NTSB stated that additional measures will be required to ensure safe operations during signal suspension.

The board issued an urgent safety recommendation to restrict the speed of trains or locomotives when passing through such areas.

NTSB chairman Robert Sumwalt said: “While the collision remains under investigation, we know that signal suspensions are an unusual operating condition, used for signal maintenance, repair and installation that have the potential to increase the risk of train collisions.

“That risk was not mitigated in the Cayce collision. Our recommendation, if implemented, works to mitigate that increased risk.”

NTSB previously issued two urgent safety recommendations to the Metropolitan Transportation Authority (MTA) based on findings of Long Island Rail Road (LIRR) accident, which occurred in June last year near Queens Village, New York, and resulted in one fatality.

The agency found that LIRR roadway workers were using ‘train approach warning’ as their method of on-track safety but did not clear the track when trains approached, thereby not complying with the established procedures.

The two urgent safety recommendations call for MTA to audit LIRR’s use of ‘train approach warning’ to ensure worker protection, and carry out corrective actions for all identified deficiencies.