I asked United Customer Service about a 1 hour connection in SFO between Terminal 1 and Terminal 3 (IAD-SFO-RNO).

They told me "there is a tram that runs between terminals. There would be no need to leave the secure area."

The only SFO tram mentioned on FlyerGuide says that it's outside Security.

The Important Notices page on United.com says "You may proceed through security at Terminal 3 and, if you are departing from Terminal 1, take the shuttle bus from Terminal 3 to Terminal 1. If you are departing from Terminal 1 and have already checked in, do not need to see a United representative, and do not have any bags to check, you may proceed through Terminal 1 security with your boarding pass. Shuttle buses depart every five minutes from Terminal 3 (Gates 71A and 87A) to Terminal 1 (Gate 39)."

I'm guessing the UA rep was mixing up shuttle bus and tram ... but I sure would like some confirmation from people who have actually been there:

Questions:
1. Do these inside-security UA shuttle buses between 3 and 1 really exist?
2. Do you think a one hour layover is long enough to land, deplane, and get to a Terminal 1 flight?

Thanks!