Reconstructing an existing road is even worse. Want to repair a failing street? OK, but only if you make every aspect of the supporting infrastructure ADA compliant with the most current laws. We are legislating ourselves out of modern infrastructure.
He's got an unpopular opinion (and calling out the ADA specifically is probably the worst of the examples that can be chosen) but its worth a thought. When the choice is forced to be "perfect, or none at all", a possible outcome is none at all.
On the balance, I find most of these rules to be acceptable most of the time, but it should always be considered that it can be taken too far.
Regulation is a commitment that we prefer "none at all" to the status quo. No more, no less. We talk about regulation creating desirable outcomes, but that's an oversimplification - the ADA does not hire or conscript anyone into the business of creating accessible infrastructure. It threatens that if they won't make their infrastructure accessible, they can't have any. The threat of "none at all" is the whole mechanism.