In 10 years time, 55 million U.S. citizens will be over 65 years of age. Most of them (over 75%) will live outside cities, in rural and suburban areas. And if they can’t drive, they’re screwed. Public transport, as it is today, will fail them.

When we talk about declining car ownership, we’re really talking about declining car ownership in cities. People still need to get around, and outside urban centers, public transport infrastructure is as bad as you’d expect in a country that’s so wholly car-oriented. Even in Europe, where cities are closer together and we have better rail and bus services, you still need a car if you don’t live in a city.

A new study from Sandra Rosenbloom of the Urban Institute details the coming transport apocalypse.

Currently, the Americans with Disabilities Act (ADA) forces public transit operators to “provide demand-responsive door-to-door services to people with disabilities who cannot use or get to conventional bus services,” says Rosenbloom. The problem is twofold. These services only need to be provided within a quarter-mile-wide corridor along existing bus routes, and because most old folks don’t have serious disabilities, they are excluded from using these services.

“Many physical or medical problems that reduce an older person’s driving skills are not serious enough to qualify as a disability,” says Rosenbloom. “The inability to quickly turn one’s neck, or correctly judge the speed of an oncoming car, or understand complicated traffic signs, or concentrate in heavy traffic.”

And even if these things did count as serious disabilities, most of these folks don’t live within a quarter-mile of a bus route anyway. Worse, these ADA paratransit services are so expensive ($3.54 billion in 2011) that few operators, says Rosenbloom, “are now willing to go beyond the minimum required by the law.” As a result, these door-to-door services are overloaded, and yet still provide service to a tiny proportion of those who could see use them.

So what will happen when so many people are stranded, unable to drive, and left without a practical alternative way to get around? The most likely outcome is that seniors will drive anyway, despite the dangers. According to Vox, “drivers are way more likely to be involved in fatal crashes past the age of 75. And for those 85-plus, the data is even worse than it is for teens.”