On a cold Tuesday morning in March, Andy Byford, the president of the New York City Transit Authority, was working the subway turnstiles—the gates, as he calls them—at the Chambers Street station, in Tribeca. Byford was seven weeks into the job, which had come with a seemingly impossible mission: to rebuild the city’s beleaguered public-transit system, after years of chaotic decline and stark dysfunction. He had vowed to visit every one of New York’s subway stations—there are four hundred and seventy-two—and to ride every bus route, in an effort that was part good-will tour, part reconnaissance mission.

“How was your trip?” he asked a commuter.

No reply. Waves of passengers rumbled past. He reminded himself to look for people who weren’t wearing earphones. Making eye contact was key.

“How was your trip?”

A young woman, not breaking stride, did a double take. “Uh, good,” she said.

Between customers, Byford straightened a pile of free newspapers. He had already introduced himself to the station agent, several platform cleaners, and the conductors on a couple of downtown trains. Each employee stared at the metal nametag pinned to his navy-blue suit. Yep, it was the president, the new guy. “Everything O.K.?” he asked. The employees seemed disarmed by his enthusiasm and his English accent. He shook hands and told people, “We’re one team.”

Byford was new to the city—new to the country—and was still perturbed by things that most locals accepted as inevitable. “That brown tiling,” he said, pointing at a rust-streaked wall. He took a photograph with his phone. Down on the platform, Byford regarded the track bed. It looked, as nature intended, like hell: filthy water, strewn garbage. “My customers shouldn’t have to look at that,” he said. “We’ve ordered three vacuum cars. They’ll suck up all of this.”

Byford, who is fifty-two, got his start in mass transit as a station foreman on the London Underground. The work ran in his family. His grandfather drove a bus for London Transport for forty years; his father worked there for twelve. Byford earned degrees in German and French, but after college he went to work for the Underground, learning car maintenance, operations, customer service, safety. He later worked on Britain’s main-line railways, and then ran mass transit in Sydney, Australia. His last stop before New York was Toronto, where, by nearly all accounts, he turned around a troubled transit system with spectacular results.

Toronto’s troubles, however, seem quaint compared with New York’s. With eight million passengers a day, the city has the largest public-transit system in North America, and, by every important metric—financial, operational, mechanical—it is in crisis. Some days, on a crosstown bus or a stalled train or a jam-packed platform, with your nose pressed into a stranger’s sweat-beaded neck and the appointed hour of your business lunch, your second date, your big job interview long past, it can feel like the system is in a death spiral. Train delays now occur roughly seventy thousand times a month, up from twenty-eight thousand in 2012. The system’s on-time rate, already among the nation’s worst, fell to fifty-eight per cent in January, down from ninety a decade ago. Bus ridership is in steep decline, caught in a negative-feedback loop with increasing car and truck traffic, slower buses, and less reliable service.

This is where Byford comes in. “New York is really lucky to have Andy,” Mike Brown, the transport commissioner of London, told me. “If anybody can take on the combination of the complex politics and the service challenge, it’s Andy Byford.” That’s not a small “if.” The Metropolitan Transportation Authority, the agency that hired Byford, is a huge and much maligned organization. The New York City Transit Authority—the M.T.A.’s largest division, with fifty thousand employees—handles subways, buses, and paratransit. Other divisions oversee commuter-rail services, tunnels, and bridges.

Physically, Byford is not imposing. He has the build of a distance runner, stands five-nine, shaves his head. If there were a contest for the palest man in the five boroughs, he would be a contender. He has blue eyes, a prominent nose, a sprightly step—he often takes stairs two at a time. A public-transportation purist, he has never owned a car. He and his wife, Alison, met while working for the Tube, and he proposed to her on a high-speed train. She’s a bank systems analyst, from Ottawa, and their vacations, he says, are nearly always “busman’s holidays—in every city, I have to check out the mass transit.” In our rambles together by subway and bus through the arteries and capillaries of what he calls, with a straight face, New York City’s “quite fabulous system,” I never saw him sit down. “The seats are for customers,” he says. More often than not, he’d start conducting customer-satisfaction surveys with randomly selected travellers, listening to their tales of riderly woe.

On the platform at Chambers Street, he studied a small group of workers, all in high-visibility orange vests, idling in a dim corner. “I wonder what they’re doing, or supposed to be doing,” he said. He decided against inquiring. “I’ve learned that it’s sometimes best not to just go steaming in.” But, when it comes to fixing the subways and buses, his approach will very much be to go steaming in. He wants to transform New York City’s mass transit—and had already committed himself to delivering a comprehensive plan within a hundred working days. “I don’t think they hired me to tweak things here and there,” he said. “This company needs a complete modernization.”

In Byford’s office, on the thirtieth floor of a building in lower Manhattan, an oversized monitor displays a real-time list of subway incidents and significant delays. It’s a detailed, constantly updated vision of Hell:

Fire on Roof of 2 Train, Smoke Issuing. Person in Altercation Fell Roadbed. Fire on Track. Debris on Track. Sick Customer. Unruly Customer. Brown Suitcase w/White Powder. Person Struck by Train. No Designation for Crew. Switch Trouble. Door Trouble. Female Threw Shopping Cart on Roadbed.

“There’s something new every twenty minutes,” Byford said. “It’s not acceptable. I want to get this down to a couple of incidents per morning.”

Head-banging seemed to be the order of the day. “I’ve just had a robust conversation with Neu”—the French transportation company, which is more than a year behind schedule on the delivery of those vacuum trains. “They told me shipping would take six weeks. I said, ‘No way. We need them now.’ Put them in a bloody Antonov and fly them over here.”

A green-and-white scarf was draped on a standing desk—the official scarf of the Plymouth Argyle Football Club. “That’s my team,” Byford said, brightening. “I’ve kept my season ticket, though I rarely get to a match.” Byford grew up in Plymouth, an old Navy city on the southwest coast of England. Argyle plays in the third tier of the English football leagues. “Strangely, I was the only Plymouth Argyle fan in my school,” he said. “All the other kids followed Liverpool or Man U. They were kids—they wanted to associate with winners. So I would wear my little green Plymouth Argyle kit, and I would be the only one wearing it, and they would all make fun of me.”