The Washington Metropolitan Area Transit Authority (Metro) announced its plan to change the way it presses wheels on 7000-series railcars (7Ks) is under development, based on technical data released by the National Transportation Safety Board (NTSB).

“We appreciate the NTSB making the technical reports available so that we can develop our plan to begin repressing wheels on these trains at a higher standard, including the fit onto the axles,” said COO Brian Dwyer. “We are preparing the technical documents and training plan, while we collaboratively advance the next version of our return to service plan for approval by the Washington Metrorail Safety Commission.”

NTSB’s investigation docket release makes it possible for Metro to transparently work toward addressing the cause of the wheel movement with a revised Return to Service Plan (version 4), according to the agency's news release.

While a cause has not been formally announced by NTSB, among the documents released was a report from experts at engineering firm Hatch-LTK which identified a technical issue — microslip due to reduction in contact pressure.

Metro added that its internal and external engineering experts agree that an increase to the fit and press tonnage used to mount rail wheels onto axles is required for the 7Ks. As a preliminary estimate, it will take up to 36 months at a cost of approximately $55 million to repress all 7K wheels.

“The process of changing all 5,984 wheels on 2,992 axles for 748 railcars may take a couple of years to complete,” said Dwyer. “We thank our customers for their patience and want them to know that the good news is we will be able to fix about 20 cars a month to safely build up more trains and restore the safe, frequent, and reliable service the region needs.”

The latest phase of Metro’s Return to Service Plan was activated on Jan. 28, 2023. The current phase marks a move to measuring the wheels every seven days instead of every four days and will remain in effect until Metro receives concurrence from WMSC on the revised plan.

Metro said it will continue its inspections of wheels with measurements for every 7000-series railcar until its wheels are reassembled at the new standard.