Metro car 4054 is loaded onto a freight truck at the Greenbelt rail yard in College Park before heading to retirement. The 4000-series models of cars, plagued by door and propulsion issues, will retire with a reputation as the system's most fail-prone cars. (Faiz Siddiqui/The Washington Post)

As the truck pulled away from the Greenbelt rail yard with car 4054, a dirty, dusty hunk of aluminum stripped of its Metro insignia, there was little of the nostalgia felt a year ago when the transit agency began retiring its original subway cars.

“There he goes,” Metro General Manager Paul J. Wiedefeld deadpanned, before slipping in a quip: “It’s a very emotional moment.”

Metro’s clunky 4000-series — riddled with door, propulsion and brake problems and, unlike earlier models, never treated to a midlife overhaul — was nearing the end of its life Wednesday, as the agency began retiring the first cars in the troublesome fleet.

The rail cars — which began arriving in 1991 and have been in service a quarter-century — will leave behind memories of stalled trains, maddening delays and the unsettling experience of doors opening mid-ride.

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“There are really three things that need to work on a train for it to go,” said Dan Tangherlini, who served as interim Metro general manager in 2006. “The doors, the propulsion system and the brakes. And the 4000-series just had an inability to keep all three of those things going.”

The cars, made by Italian manufacturer Breda — which made two earlier series still in service — cost about $1.3 million apiece and logged about 1.5 million miles each during their life span.

The 100-car fleet was gradually introduced into the system to supplement service on the initial portion of the Green Line when it opened in 1991. And while they carried Metro through the completion of the original system in 2001 — as ridership boomed — the series has had to be pulled from service at least three times since then, according to the agency.

In 2010, the cars were sidelined because of reports that doors were opening before trains reached the platform. Five years later, the fleet was yanked again for the same problem. The final straw came in November, when Metro pulled the series and then decided to “belly” the cars — sandwiching them between more reliable models — after discovering a control glitch that might cause a collision if one of them was in the train’s lead position. The transit agency determined that it didn’t have the equipment to fix the problem.

By January, the 4000-series cars were far underperforming every other model in the Metrorail system. They broke down almost twice as often as the slightly newer 5000-series. And the 6000-series, the agency’s most dependable fleet through 2016, was almost four times as reliable, with the 6000-series trains averaging 101,000 miles between delays last year, compared with the 4000-series’ 26,000.

To put it simply: “It’s the weakest link in the chain,” Wiedefeld said.

Often, problems with 4000-series cars would snarl trains made of otherwise-reliable cars. Metro expects to see an uptick in performance as the cars are retired and more 7000-series models arrive.

“The sooner we get those off of here, the more 7000s we get on the system, the better for our customers,” Wiedefeld said.

So how did cars commissioned in 1991 come to be condemned to the scrap heap years before models that were built decades earlier? Current and former Metro officials said a combination of funding shortages, maintenance and technology challenges, and timing contributed to their early retirement.

For starters, the 4000s run on a power system that was nearly outdated the moment they arrived.

Even as many rail cars were being upgraded to a more advanced and efficient alternating-current power system in the 1990s, the 4000s arrived with direct-current motors that were never upgraded, Metro officials said. Even so, the older cars were mixed with modern technology in the rehabilitated fleet.

Experts say mixing cars with two different technology platforms makes that train set more likely to fail.

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And mixing the technologies in train sets made failures more likely, particularly when it came to doors. The 4000-series cars have analog circuitry in their doors, while the upgraded models in the legacy fleet have more reliable and advanced digital equipment, officials said.

Cutting-edge technology was not the aim when the 4000s were procured, said David L. Gunn, who was Metro general manager from 1991 to 1994. Rather, rail cars were being added to meet capacity needs as the system grew.

“You built in a newer technology, but it wasn’t a great leap forward,” Gunn said Wednesday from his home in Nova Scotia. “It was an expansion. But ultimately, cars, you figure, are good for 30, 40 years, or even 50 years if they’re well maintained,” he said.

Moreover, Gunn said, Metro’s fleet increased by 30 percent from 2002 to 2010, but its maintenance staff only grew by 10 percent in that time — leading to a decline in work quality just as the 4000-series cars reached midlife.

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Today’s problems, officials said, can be traced back to Metro’s decision not to give the fleet midlife upgrades.

“What happens is that toward the end, the fatigue sets in; no matter what you do, you cannot keep up,” said Sachit Kakkar, Metro’s chief engineer for vehicles. “Had those cars gone through the midlife overhaul, and we had put enough money into overhaul, this car would still be great.”

Between the mid-1990s and 2000s, the 1000-, 2000- and 3000-series cars all went through midlife modernization, extending their life spans. Funding shortages prevented the 4000-series from receiving the same treatment, officials said. And because of the outdated power system and other factors, there was an “inability” to obtain spare parts, Kakkar said.

The factors combined to make the 4000-series less reliable, even, than the original model put into service when the system opened in 1976. That model, the 1000-series, was deemed un-crashworthy by the National Transportation Safety Board after the June 2009 Red Line crash at Fort Totten, and Metro prioritized its retirement. Metro said 104 of the 1000-series cars remain, down from more than 280 when the decommissioning process began.

Today, because of their individual safety concerns, the 1000- and 4000-series models are the only ones condemned to be bellied between more reliable cars.

[Metro pulls rail cars from service after discovering collision risk]

Now, the agency aims to remove all 1000- and 4000-series cars from passenger service by the end of 2017, before moving on to the 5000-series models, which number about 200 and will be replaced by the 7000-series.

Eventually, Metro plans to replace more than half the fleet with the new 7000s, manufactured by Kawasaki. The effect of retiring the old models is unlikely to be felt by riders, though — Metro is receiving about 20 of the new cars per month and getting rid of 16 to 19 of the older models. By late last year, 4000-series cars still in service made up about 7 percent of the 1,212-car passenger fleet.

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The 4000-series models will now be stripped of their Metro logos, radios and some reusable components and sent to Baltimore, where they’ll be scrapped in accordance with Environmental Protection Agency requirements. Afterward, Wiedefeld said, some might be donated to police and government agencies for safety training. Unlike the 1000-series models, he said, there will probably be little interest in preserving them.

Tangherlini gave the cars, which contributed to so many delays over the years, an abbreviated eulogy.

“Goodbye and thanks for some service.”