Caltrain has actually worked on this for 4 - 6 years. They are proceeding on the assumption that their electrification will be part of the CA HSR. The preliminary EIR (Enviromental Impact Report ) has been submitted and some revisions incorporated. Now the final EIR has now been approved by the Caltrain board and can be found at the following link. Note: you will need to access each of the sections separately. One section is over 24Mb. Great bedtime reading to go to sleep. Put me under 5 nights.
Single-track catenary? Are there sidings on this route?
Nice and modern, too. 25 kilovolt (kV), 60 Hertz (Hz), single-phase, alternating current system, also mentioned specifically to be compatible with California HSR system but those rendered pictures in the report don’t look like high-speed catenary, so it’s mostly likely so Caltrain can use the HSR routes, or maybe just standardize on equipment.