The hundreds of pages of technical reports made public on Tuesday include test results and analysis intended to help investigators identify the cause of the derailment. The data does not include a formal probable cause for the derailment, but a series of specialist reports provide the clearest view of the findings that will help shape the safety board’s final conclusions.
The timing of Metro’s service problems has coincided with the region’s attempts to recover during the pandemic, frustrating elected leaders and commuters while bringing Metro’s management and safety record under increased scrutiny.
Transit leaders said they will develop a plan for the near-unprecedented step of mounting 5,984 wheels on 2,992 axles of the 748 carriages in the series. Metro Chief Operating Officer Brian Dwyer said Metro aims to retread about 20 cars each month.
“We appreciate the NTSB making the technical reports available so we can develop our plan to begin suppressing the wheels on these trains at a higher level,” Dwyer said in a statement.
Metro hopes the repairs will be a permanent solution to a time-consuming problem for its staff, who must regularly check the wheels on its 7000 series cars under an agreement that allowed them to return to service. Metrorail’s safety regulator, an independent agency created by Congress, has agreed with Metro’s plan, saying the crackdown should improve safety but won’t solve all the derailment-related problems.
The reports raised questions about Metro’s tracks, including the placement of restraining rails that help trains navigate curves and the unusual speed at which wagon wheels wear out.
“Research has shown that there are probably multiple factors contributing to all of this,” said Max Smith, a spokesman for the Washington Metrorail Safety Commission. “The design needs of the axle assembly may affect one of the factors, but it does not affect all of the factors.”
The transit agency has looked to move beyond the pandemic and the suspension of rail cars — dual crises that have halved Metrorail’s ridership amid a shift to telecommuting while also affecting the ‘financial stability of the agency.
The agency has embarked on an aggressive plan to restore frequent rail service in the summer, similar to the levels the transit system was operating at before the pandemic. Metro spokeswoman Kristie Swink Benson said the wheel assembly project, however lengthy, won’t put a damper on those plans.
What began as a relatively minor derailment on October 12, 2021, between the Rosslyn and Arlington Cemetery stations on the Blue Line, with no serious injuries, turned into one of the longest service problems in the history of the transit agency. An NTSB investigation into the incident found that a single car of the eight-car train had slid off the tracks because its wheels had moved about two inches apart on the car’s fixed axles.
The faulty car caused the train to derail several times on its final run, going through switches again before stopping short of the Arlington Cemetery station. It tore up concrete grout pads while breaking brake discs and other parts along the way, causing $161,750 in damage to track, signal and train control components, according to the report.
Investigators, including those from Metro and the safety commission, have said they suspect the defect that causes the wheels to move off the fixed axles is the result of many factors, including how the cars interact with the road and the force with what was the pressure on the wheels. axles They have said they do not blame the manufacturer, Kawasaki Rail, which delivered the cars to Metro between 2014 and 2020.
Emergency inspections and a review of records in the days after the derailment found similar movements in about 50 other cars over a four-year period. Despite repeated repetitions, neither Metro inspectors nor supervisors notified officials of the safety department, higher transit agency management or the safety commission, considering that the defects were isolated requiring repairs or replacements under car warranty.
Shortly after the derailment, NTSB Chair Jennifer Homendy said the movement of the wheel could have been catastrophic had it not been caught. The safety commission suspended the 7000 series cars on October 17, 2021.
The cars had been Metro’s most modern and reliable to date, accounting for nearly 60 percent of the transit agency’s fleet. Its suspension created a shortage of trains, forcing transit officials to pull 40-year-old cars from storage and speed up repairs on older cars to fix enough trains to keep the system open.
The shortage forced Metro to drastically reduce frequencies, with some rail lines initially running trains every 25 minutes.
In May 2022, the discovery of a recertification lapse among half of the train operators led some officials, including D.C. Mayor Muriel E. Bowser (D), to publicly question Metro’s leadership, leading to to the resignation of Metro CEO Paul J. Wiedefeld. and Chief Operating Officer Joseph Leader on the same day.
The safety commission allowed Metro to put the cars back into service last summer under a plan that required Metro to regularly inspect the wheels of the 7000 series cars.
After controversial public spats between Metro and the safety commission over the pace of putting 7000-series cars into service, the commission in January allowed transit officials to conduct wheel inspections less frequently. That move freed up Metro to increase train frequencies to a point where agency officials hope to run pre-pandemic levels of service this summer.
Among the reports released Tuesday was an October 2022 test report from Kawasaki, the railcar maker, which cited the results of what it calls “back-to-back wheelbase research,” or “BtB.”
“Through the test results, it is assumed that a combination of outward lateral forces applied to the wheel and variations in bending stress in the axle that occur during the run (both in line main as in the yard) causes the BtB distance of the wheel to increase,” Kawasaki found. .
A separate January 2023 report by rail engineering firm Hatch LTK said its analysis of problematic wheelsets and review of published papers on unsafe wheel movements led to the conclusion that with loads of higher steering, the wheels and axles are pressed together with a large loss of pressure. part of this bond and become vulnerable to bending.
The 2023 report said these findings are also “consistent” with previous research by Hatch LTK, which indicated that the wheelset has insufficient contact pressure because it is mounted without the appropriate amount of force “for the vehicle 7K operating in the WMATA environment.”
Metro said in a response to a separate analysis by MxV that all parties to the NTSB investigation agree that “the wheelset incurs contact pressure loss during operation and that the mitigation proposed by Metro – to increase interference fit and also increase press tonnage – will effectively address all likely mechanisms identified that can cause wheel migration in the 7000 series fleet.”
But Metro also said separate probable cause theories put forward by MxV involving vibration and temperature “are inconclusive and lack the supporting data to provide the level of certainty Metro sought from MxV’s work.”
The documents also point to long-standing safety management issues facing Metro and underscore concerns raised by the rail system’s safety regulator. In responses to NTSB questions about Metro’s oversight, the safety commission said it “has had to address ongoing efforts by Metrorail to massage or ignore relevant safety data and information.”
Metro’s safety regulator also said it had been left in the dark about key issues at safety meetings.
“Metrorail did not report [safety commission] of gauge exceedances followed in any of these rail car assemblies, he did not provide any information about these exceedances as part of the documentation for the [safety commission’s] Wagon Audit, and failed to mention these ongoing gauge exceedances or the increasing number of such exceedances detected in any way when repeatedly asked orally and in writing about any safety issues that had not been discussed,” wrote the security commission.
Investigative documents released Tuesday also noted that many Metro leaders were caught off guard by a wheel defect that had appeared more frequently before the derailment. Investigators pointed to a lack of clear reporting guidelines that allowed recurring wheel inspection failures to escape Metro’s safety department.
Metro Safety Director Theresa M. Impastato told investigators that there were no barriers that would have prevented the Metro department that monitors vehicle reliability or any other department from knowing about the recurring wheel problems, according to the documents feds published on Tuesday.
He said when the problem was first identified, the transit agency had no criteria that supervisors could reference to determine whether the wheel problem should be escalated to other departments. Impastato told investigators that Metro is reviewing its process for reporting safety issues.
Meanwhile, federal investigators conducted walking inspections of Metro tracks and found issues previously raised more than seven years ago with rail width, as well as other design issues that could contribute, but not cause, derailments.
TTCI, a consultant hired by Metro after the derailment, also found 27 points that are more difficult for car wheels to maneuver than elsewhere on the system. The problem areas, the consultant said, were unlikely to set the wheels in motion without other contributing factors.
The report underscores what officials have been saying for months: The wheel movement isn’t driven by a single factor.
“At this time, TTCI does not believe that any of these locations produced an impact severe enough to move the wheel and is called the sole primary cause,” an investigative report concluded.
