Both the regular and the Fastpass Lines are wheelchair and
ECV accessible until the point where you pick up the 3D glasses. That is also the point where Fastpass and regular queue merge. Depending on the ECV, some may be more challenging to go thru the regular queue with (thinking of some of the very wide or long ones).
At the glasses pick up point, there is a stairway up and down to cross over the track in the regular line. Guests with mobility disabilities or who can’t do stairs are routed to the ramped area to the right of the stairs. Guests with visible needs to avoid stairs (ECV, wheelchair, walker, rollator, crutches, etc.) will be routed to the ramped area automatically, without needing a GAC (Guest Assistance Card).
There is no guarantee of how a Guest Assistance Card is going to be handled at an attraction and not all GACs are handled the same way. This can be true, even at the same attraction on the same day.
How it is handled depends on the needs of the person, what is happening at the attraction at that time, along with what is available at the attraction.