One more thought is that maybe the work is scheduled to be finished by the time you take your trip? The Amtrak website is a bit unsophisticated, and can show "alerts" even when the track work is on a different day to the one you need.
Doubtful, in this case. It appears the OP had the bad luck of booking a trip on one of just two days that all train service is cancelled south of Jacksonville due to
a bridge replacement undertaken by the owners of the track.
http://www.amtrak.co...d=1251622516947
The OP should be glad s/he is not going all the way to Miami: That would be a 10hr bus ride. OTOH, the OP makes a good point about not being notified. It's possible
that notification is still on its way, since the travel dates are still more than a month away. And technically, there's nothing about this that would effect the OP's schedule,
since the bus is scheduled to arrive KIS at the same time as the train.
To the question about the wheelchair, virtually every single bus these days has a lift, so theoretically that's not an issue. Inconvenient, yes. But from Amtrak's
point-of-view, they'll get you there. No one likes a bustitution, but in this case the track closure is not Amtrak's fault, and the alternative would simply have been
to cancel the service altogether. I bet a lot of people prefer the substitute bus to nothing at all. But, yeah, here on AU we feel your pain.