Ah, page 8 of the pdf makes clear something I didn't realize: the crossover is itself in a vaulted section of the Red line, versus just in the tunnels. The NBC animation made it appear that the new ceiling being installed was in the Medical Center station itself, not in the crossover area.
Edit: I just read John's helpful post carefully and see he also clarified the issue was in the crossover gallery not the station itself. John - how many crossovers are in galleries, versus just tunnels? From experience on the lines I ride, I thought all crossovers were just in tunnels.
Along the A route end of the Red line north of Farragut North, all 4 of them. Dupont Circle, Van Ness, Friendship Heights and Medical Center. On the B route end, Forest Glenn and Wheaton, they are semi galleries. All of the remainder of the double crossovers in subway are in cut an cover concrete tunnels.
Semi galleries as in galleries over the turnouts and the diamond crossing in the center of the double crossover. The 5 smaller galleries 1 for each of the 4 turnouts and 1 for the diamond crossing are connected by short tunnel segments that are the same dimension as the mainline tunnels. The reason for the semi galleries is because of the broader track centers along the B route end of the Red line to accommodate the separate single track single platform station arch vaults.
Mind you the B route end doesn't have water intrusion issues as the entire length of the route, tunnels, stations and crossovers were water proofed using the geomembrane system as described in option 1 when they were originally built.
John in the sand box of Maryland's eastern shore.