A Metro train passes track that has buckled in the heat on July 22, 2016, near Ballston. (Katherine Frey/The Washington Post)

The Federal Transit Administration is threatening to withhold millions in funding from Metro if the transit agency does not take urgent steps to address worker safety on the tracks, the federal agency announced Monday.

In a letter to Metro General Manager Paul J. Wiedefeld, the FTA requires Metro to submit plans to address six deficiencies related to roadway worker protection within five business days or risk losing up to 25 percent of a formula-based grant fund until the issues are addressed.

“I find that unsafe conditions and practices exist that present a substantial risk of death or personal injury to roadway workers,” Thomas Littleton, associate administrator in the FTA’s Office of Safety and Oversight, wrote to Wiedefeld.

FTA assumed safety oversight for the troubled transit system in October 2015 after the previous body, the regional Tri-State Oversight Committee, was deemed ineffective. The FTA has conducted a series of reviews of the transit agency’s safety practices since the deadly 2015 L’Enfant Plaza smoke calamity that killed a 61-year-old grandmother and sickened scores of others. They included a 2015 safety management inspection that found significant flaws in the agency’s rail control center, the train system’s nerve center that makes decisions critical to worker safety.

On multiple occasions, FTA has also raised concerns about the safety of track workers and inspectors, who walk throughout the rail system during hours of operation to assess or repair track defects. Last October, a train nearly struck two federal inspectors and a Metro worker on the tracks near the Reagan National Airport station; the train was moving faster than the 10 mph speed limit as it came around a blind corner, and a Metro worker posted as a lookout yelled for the other three people to jump out of the way as the train barreled in their direction. At the time, Wiedefeld called that incident “very concerning” and vowed to beef up training and use new technology to prevent similar near-misses.

Each of the actions prescribed by FTA on Monday relate to “foul time,” or the period when tracks are out of service and there may be workers or other personnel in what the transit industry calls the “roadway.”

In its letter, FTA mandates that Metro must submit work plans to address each of the following:

1. Require the use of at least one redundant protection method implemented by field personnel to hold trains outside of a work zone when utilizing Foul Time protection.

2. Clarify the conditions or roadway areas in which Individual Train Detection (ITO) and Train Approach Warning are insufficient levels of protections and a higher level of protection, such as Foul Time, must be utilized.

3. Clarify rail controller-rail operator-roadway worker communications to implement, document, and release Foul Time consist with WMATA’s permanent order requiring a 100 percent repeat back radio protocol.

4. Reduce rail controller distractions, workload, and potential for miscommunication when handling Foul Time requests.

5. Determine compliance with Foul Time requirements.

6. Require a Safety Stand Down to brief rail control personnel, personnel who work on the roadway, and train operators of the changes resulting from items one through five above.

Metro spokesman Sherri Ly said the agency is focused on addressing the issues highlighted by the FTA and has already taken steps to improve safety — including implementing stricter procedures at the Rail Operations Control Center, requiring staff to document what instructions have been communicated between controllers and train operators.

“We share the FTA’s concerns and are working closely together on roadway worker protections,” Ly said. “We will provide a full and timely response to all of the recommendations in the FTA’s letter.”

One new piece of technology Metro has introduced recently: a “portable train detector warning system,” a wearable alarm that workers and inspectors can use to alert them to oncoming trains. The arm bands emit a flashing light and a loud beep that alerts workers that they urgently need to get off the tracks. They began putting the armbands in use this year, at the same stretch of tracks where the October incident occurred. The technology was paid for through a grant from the FTA.

In the letter, Littleton lauds Metro for steps it has taken to ensure worker safety but says more needs to be done — and urgently.

“While we recognize WMATA’s progress … FTA is concerned that procedures are not being followed, protocols for Foul Time application are ineffective, staffing limitations in the [rail control center] continue, and distractions in the [rail control center] impede safe operations.”

The FTA notes that of 32 roadway worker protection-related actions required of Metro, 19 remained open and past due as of last week. Ten were either closed or under FTA review, the agency said.