Passengers make their way on and off the train at Pentagon City Metro station on Aug. 6. A train derailment at Smithsonian caused plenty of headaches for the morning commute. (Brittany Greeson/The Washington Post)

Metro’s board will meet in a closed session Wednesday to review the results of an investigation into the Aug. 6 derailment and discuss “potential disciplinary action” against agency employees.

Michael Goldman, chairman of the board’s safety committee, said Tuesday that the investigation report was prepared by Metro officials who oversee rail operations and was delivered to the board this week.

“It addresses what different individuals did and how this happened,” Goldman said of the about 130-page document.

The train, which was not carrying passengers, went off the rails near the Smithsonian Metro station shortly after the system’s 5 a.m. opening. The incident closed two stations and shut down service on parts of three lines for nine hours, leaving tens of thousands of riders scrambling for alternatives.

Officials later said it was caused by a track defect that had been detected a month earlier but wasn’t repaired.

Although Goldman said his “goal” is to publicly release the report by the end of the week, the board’s initial review of the document will take place privately Wednesday in an executive session. On Metro’s Web site, the subject of the hastily scheduled meeting was described simply as “Personnel Matters,” without elaboration.

“Because it involves potential individual personnel matters, and potential disciplinary action against individual personnel, we thought that was an appropriate reason not to have it as a public meeting at this stage,” Goldman said. When the report is made public, the names of employees implicated in the incident will be redacted, he said.

He declined to discuss details of the report, saying, “I want to give my colleagues and myself a little time to digest it, and then we’ll go from there.”

Goldman previously scheduled a special safety committee meeting for Sept. 3 to publicly discuss the investigation report. The next public meeting of the panel had been scheduled for Sept. 24, but Goldman moved the date up as members of the Washington region’s congressional delegation unleashed yet another barrage of criticism at Metro, demanding immediate answers about the derailment.

For a transit agency chronically beset by infrastructure problems and service disruptions this year — including a Jan. 12 electrical malfunction that filled a rail tunnel with smoke, killing one train rider and sickening scores of others — the derailment was another in a series of black eyes.

The derailed train caused Metro to close the Smithsonian and Federal Triangle stations for the day and shut down service for hours on the parts of the Orange, Blue and Silver lines. Commuters had further cause for anger when Metro acknowledged that track inspectors a month earlier had detected the problem that caused the derailment.

The transit agency publicly apologized and said it issued $750,000 in fare refunds to 158,000 SmarTrip card holders who were inconvenienced.

In addition, the agency’s top engineer ordered emergency track inspections across the system and targeted, enhanced inspections in the immediate area of the derailment. Metro also has implemented speed restrictions on curves throughout the system as part of what the agency calls an “aggressive campaign” to inspect curved sections of track after the Aug. 6 incident.

Ideally, Metro’s parallel subway rails are supposed to be 56 1/4 inches apart, although small variations are considered safe.

At the site of the derailment, several fasteners that hold the rails in place were “either loose or missing,” Metro’s interim general manager, Jack Requa, told reporters after the derailment. Because of the trouble with the fasteners, the rails were a dangerous distance apart. The problem, “wide gauge” in rail parlance, eventually caused a train’s wheels to leave the tracks.

“The track should have been taken out of service” when the problem was detected, Deputy General Manager Rob Troup said. As weeks passed and trains continued to rumble over the trouble spot, the problem worsened until the derailment occurred. “We’re trying to understand where the chain of command broke down, where the notification broke down, where that happened,” Troup said at the time.

Because no one was injured in the accident, the National Transportation Safety Board opted not to conduct an investigation, leaving the inquiry to the local Tri-State Oversight Committee, which monitors Metro’s safety.

However, the NTSB said, the derailment “does inform our ongoing investigation” into the Jan. 12 fatal smoke incident, which occurred in a Yellow Line tunnel near the L’Enfant Plaza station. “Organizational culture and infrastructure are two of the issues that we’re looking at in the L’Enfant investigation, and this recent derailment incident is another data point in each of those areas,” the NTSB said.

Goldman said the report given to the Metro board this week will be incorporated in the larger final report to be issued eventually by the Tri-State Oversight Committee.