I would say it's many things.
The old fleets don't necessarily have to meet current or new accessibility requirements, but the new fleets do, so it's a continuous process. Many of the services are on demand. If an individual arrives in a wheelchair, the people working that day need to know how to support that individual in gaining access to a train, and so on. There are a lot of training requirements about the facilities, individuals and websites.
I think it's across the gamut, if we want transportation to be barrier-free in the country.