For most of its length on the SF peninsula corridor the catenary clears Plate H double stack cars (contact wire at 23 feet above rail), so the height of the EMUs is hardly the issue. I suspect the HSR rolling stock will need two pantographs: a passive long reach model for corridors used by freight, and an actively controlled and aerodynamic short reach model for dedicated high speed corridors.

Interestingly all of the new HSR grade separation overpasses in the Central Valley look like they will clear Plate H, so I am curious to see what wire height they pick. At very high speeds you don’t want long pantograph extensions because of drag and noise.