I don't know whether they will be using side supports or stanchions, but even if they add a service with the faster turn on the southern part of the San Joaquin corridor, its only seven trains per day. You can just pause work for 15 minutes when the train is approaching until its passed by. Operations like placing stanchions over the line could be done at night, since the San Joaquin does not run all night.

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