Peggy Darlington has always loved the New York City subway. As a little girl, she rode the trains frequently, and when she wasn’t on a train, she played “train” in her bedroom. One day, Darlington’s parents ordered her to play with dolls. After finding that she had put the dolls on pieces of cardboard to shuttle them around, they finally relented. “That’s when they gave up, that’s when they knew I’d never play with dolls,” she said.

Over a half-century later, Darlington, now 53, remains infatuated with trains and the lore that they encompass. But it wasn’t until 1997 that she was able to put her affection for rail transit to practical use. That was the year she saw an advertisement placed by the Metropolitan Transit Authority. Less than 12 months later, Darlington began working as a station agent, selling tokens and imparting directions and assorted information. Today, she still works the “lunch relief” shift, from 2 a.m. to 10 a.m., shuttling from booth to booth, filling in for agents during their half-hour breaks. She failed the physical exam required to become a conductor, but is only a little bitter. And she continues to take the job that she has very seriously.

Shortly after landing her dream job, Darlington, a self-proclaimed “rail nut,” did a search on the Internet for sites devoted to the subways and found one run by a systems management consultant at a New York City financial firm. “They were asking for volunteers to do line by line summaries and I said, ‘I’ll do you one better: I’ll do it station by station,’” she said. “I did the entire subway except the L line, and the only reason I didn’t do the L train was because someone beat me to it.” Darlington brought to the task a lifetime of information, fascinating in detail and broad in scope. And what she didn’t already know, she set out to learn – subway line by subway line, station by station. One particular train route required more work than she expected. The A line, which runs from the northernmost tip of Manhattan through Brooklyn and settles on the Rockaway peninsula, took Darlington four trips to research, mainly because she had to do it in pieces. What she found was that part of the line, like Darlington herself, had an unusual history.

The Rockaway line of the A train was built in 1892 by the Long Island Rail Road. Railroads are different from subways, and on a recent morning tour, Darlington easily recognized signs of the A train’s origins. As the car screeched through its downtown route, bathed in Queens sunlight, Darlington’s small eyes widened at the sight of the slinking platforms.

“Look at how long they are! These were built for 85-foot-long cars, subways use 75-foot-cars,” she shouted, startling the few bleary-eyed patrons sharing her train. Darlington speaks, even when not on a train, with a deep bellow that she seems unable to soften. On one platform, she looked down her nose at the low railings and diamond pattern in the concrete, both signs of what she considers the station’s embarrassing ancestry. “Typical concrete of the Long Island Rail Road, typical bland LIRR construction,” she scolded. The old LIRR stations, as Darlington pointed out, are masses of concrete, with huge ceilings and colossal mezzanines; side by side, any one of them would dwarf the average subway station, rendering it almost claustrophobic.

She strolled confidently through the cavernous stations and on the long platforms. Still wearing her fluorescent orange New York City Transit vest long after her shift had ended, Darlington stopped briefly to peel an errant piece of tape from one of the too-low railings, and a second time to command a man to put out his cigarette. She was especially sharp in reprimanding the smoker, perhaps because he reminded her of the destructive role tobacco played in the history of the A train.

In 1950, when Darlington was a 2-year-old living in Brooklyn, a fire broke out on the tracks of the Rockaway line. The line connected the city to the Rockaway peninsula with wooden bridges that ran over Jamaica Bay (“If the train stopped for long enough, you could put a pole out and get a fish for lunch,” Darlington barked, taking a break from chewing on her already well-bitten fingernails. “Get a fish for lunch!”) In time, mussels and other sea creatures grew up the bridge columns and ate through the wooden cross ties of the tracks, hollowing them out. Train riders then stepped in, becoming accidental arsonists.

“They kept having fires from people throwing cigarettes out the window,” Darlington explained. The air, which passed freely through the hollow wood, fanned the flames and repeatedly started fires that would shut service for three to four months at a time. After the particularly large blaze in 1950, the Long Island Rail Road sold the tracks to the city for $8.5 million –“fire sale prices,” according to Darlington.

The city invested $47.5 million dollars into the line to adapt it to subway use. It pumped fill from the bay to create two man-made islands for the bridge columns to prevent future damage from sea creatures, fireproofed the bridge to protect it from cigarette smokers and then electrified the tracks. In 1956, the Rockaway line of the A train became part of The Independent line, one of the three former competing subways systems.

While in one form or another the tracks connecting Manhattan to Queens have been in almost continuous service for 110 years, Darlington’s relationship with New York’s rail system has not been quite as consistent. When she was 17 years old, her father was transferred by his employer to Memphis, Tenn., and he took his family with him. It took her almost 30 years to get back here, “and I would have come sooner if I could, believe me,” she said. Now that she has returned, immersed in a job and a vocation that fulfill her every childhood fantasy, few aspects of rail travel in New York escape Darlington’s attention.

As she sat, fidgety, on an A train in Far Rockaway waiting for the signal to head back to Manhattan, a pigeon walked through the door. “Look at that pigeon in the train! I’m sure he didn’t pay the fare,” she yelled, only half-jokingly.