Darkness had fallen. And there I was, rolling uptown through fog and rain, out of Chelsea along 12th Avenue in an old Citroën with yellow French headlights, quietly thinking, “I must be the nuttiest guy on the road.” Suddenly, an even more lunatic road user overtook me: a young man in business dress riding an electric unicycle. He had a briefcase clutched under one arm and a phone in his other hand, traveling close to 35 miles per hour, weaving in and out of traffic with nothing but dim streetlamps to light his helmetless way along the greasy thoroughfare. As a steady drizzle fell, the chap—who, in fairness, was either extraordinarily athletic or benefiting from some sort of gyroscopic assistance—startled driver after driver, managing to remain upright, though at great risk to himself.

Such experiences are common these days. Adding vast numbers of bikes, e-bikes, gas scooters, electric scooters, motorcycles, and, yes, electric unicycles to streets already congested with (often badly driven) cars, trucks, and buses—not to mention the millions of often inattentive and electronically distracted pedestrians—may trim harmful emissions. But the new transport options have also ramped up the sense of chaos on the roads, presenting horrifying new opportunities for operators to hurt themselves and others.