New York City’s subway system in the US has been restored after it underwent an unprecedented system breakdown due to a brief power failure that disrupted half of the system.

The breakdown, which lasted for several hours, affected over 80 trains, leaving hundreds of commuters stranded.

At a briefing with Metropolitan Transportation Authority (MTA) officials, New York Governor Kathleen Courtney Hochul said that ‘a sequence of failures’ left some backup systems unable to provide power.

The restoration of service was delayed as commuters on two of the stuck trains got off onto the tracks by themselves instead of waiting for rescuers from agencies.

The breakdown started on 29 August, when energy company Con Edison reported losing a feeder ‘for a short period of time’, causing a voltage drop across New York City.

This activated the MTA’s battery-powered backup electrical system.

However, these batteries can temporarily energise the system until two generators are activated automatically.

The system therefore continued running on the batteries as the generators never turned on.

Hochul said: “At about the same time, two power plants and generators went offline. It was a momentary outage that did go to the backup system. When it tried to go back to normal, there was a surge, an unprecedented surge that resulted in the subway losing signalisation and communication ability and it lost that between its command centre and the trains throughout the system.”

Furthermore, failure of an alert system left workers in the control centre oblivious to the situation and, after around 45 minutes, the batteries were drained and the subway system came to a stop.

MTA has been directed to retain two independent engineering firms ‘to assist in a thorough deep dive of what happened and make recommendations to ensure this does not occur again’.

The city agencies have also been cooperating with the state and MTA to further investigate the disruption.