If one were to build the Second Construction segment, and use the existing Antelope Valley line to complete the run to LA Union Station, the service would have to be hybrid diesel-electric service, since the Bakersfield to Lancaster segment will have tunnels and viaducts to get over the Tehachai pass that are not designed for diesels to pass through. So that bridge service (which is not in the CHSRA baseline, I must stress) would have to be electrified Palmdale through Bakersfield, and one might as well electrify the Bakersfield to Merced section to make a 200 mile electric section.

But absent such a bridge service, which would be time-competitive with driving but would not attract a lot of current air travel unless there was a petroleum crisis, the first electrification would be when the Express HSR corridor down into the LA Basin is completed and an Initial Operating Express HSR Service within the Proposition 1a can be started.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

Following that approach, it would be relatively easy to isolate one side for purposes of overhead catenary construction while using the other side. Although the workers would have to be pretty brave...