The Washington Metropolitan Area Transit Authority (WMATA) in the US has received orders to not operate nearly 60% of its rail fleet as part of an investigation into a recent derailment.

In the absence of rail cars, the subway system will run nearly 40 trains and provide a basic service pattern on all lines of trains departing almost every 30 minutes, reported Reuters.

This is expected to cause significant delays for commuters.

This suspension has been initiated by an ongoing National Transportation Safety Board (NTSB) probe.

This investigation is looking into the derailment of a Blue Line WMATA train that occurred last week between Rosslyn and Arlington Cemetery stations in Arlington.

The incident did not injure any of the 187 commuters onboard.

The 7000-series trains were stopped from service after the NTSB ‘identified safety concerns related to the spacing of wheels on 7000 Series railcar axles’.

A spokesman for the Washington Metro Safety Commission was cited by Reuters as saying: “The 7000-series cars were built by Kawasaki Heavy Industries and its subsidiary New York-based Kawasaki Rail Car Inc, which delivered the first railcars to WMATA in January 2014.”

These rail cars will not enter service until a plan has been developed to study the cause and devise a strategy to identify as well as prevent these wheel assembly problems.

The subway system is expected to provide updates regarding the service for the remainder of this week.

In August, WMATA’s subway service was 26% pre-pandemic levels on weekdays and roughly 50% on weekends.

In March this year, Hitachi Rail Washington won a contract from WMATA to design and build 256 of the 8000-series railcars.