The 4 train departed Woodlawn at 11:38 p.m. on August 27, 1991, six minutes behind schedule. Ray's blood alcohol level, measured roughly thirteen hours after the crash, was still 0.21 — more than twice the legal driving limit. How drunk he had been at the controls is a matter of extrapolation, but the answer is: very. The NYCTA had regulations requiring conductors to report impaired operators to the command center. Beerram did not follow them. The reasons were human and systemic: pulling the emergency brake meant paperwork, delays, and making a colleague's problem public. The culture of the system — understaffed, underfunded, running on a century-old infrastructure — made it easier to hope the problem would resolve itself. It did not resolve itself.

Construction that night required southbound express trains to switch to the local track via a pocket track between the two lines. The crossover demanded a speed of 10 mph. Ray's train arrived at many times that. The first car struck a steel support column and crumpled. The second car, where most of the dead were found, jackknifed. Five R62 subway cars were destroyed — 1440, 1435, 1437, 1439, and 1436. Two sets of track, a third rail, two signal sets, two switches, and an air compressor room were demolished. The crash site was close enough to the platform that it served as the triage area. Ray walked away uninjured, sat on a park bench while rescue workers extracted his passengers, and was arrested at 5:30 a.m. returning to his apartment. He was sentenced to five to fifteen years for manslaughter, plus concurrent terms for assaulting twenty-six of the injured. He was released in April 2002.

A 1992 study commissioned after the crash confirmed what investigators had suspected immediately: some signals on the Lexington Avenue Line were spaced too closely for a train at maximum speed to stop in time. The system's century-old signal infrastructure had never been designed for the speeds modern equipment could reach. The finding resurfaced three years later after a rear-end collision on the Williamsburg Bridge. The NTSB recommended speed indication systems for all subway cars. By 1994, gear-unit systems were installed on the R44 and R46 fleets, and Doppler radar systems were ordered for the R62s — the same type of car that had been destroyed at Union Square. Ultimately, the crash accelerated the adoption of communications-based train control across the subway system, a modernization still underway decades later.

The MTA announced random drug and alcohol testing for motormen and bus drivers the day after the crash. The pocket track where the derailment occurred was removed and replaced with a simpler diamond crossover. New diverging grade time signals forced trains to slow down earlier before switching tracks. Service resumed six days later, on September 3, after round-the-clock debris removal over Labor Day weekend. The five destroyed cars were permanently retired. The estimated payout to victims ranged from $5 million to $10 million. In 2015, Robert Ray was critically injured in a hit-and-run accident in the Bronx — a detail that reads like a novelist's invention but is simply the kind of thing that happens to people whose lives went wrong a long time ago. The crossover at Union Square still exists. Trains still slow to pass through it. The difference is that now, the system no longer relies entirely on the sobriety of the person at the controls.