Google Maps indicates an hour walk. MapMyWalk show a 186 elevation gain, which I suppose is not too terrible considering it gradually increases until about the halfway point, and then gradually decreases. Add a laptop and hefty book into the mix, and you've got yourself an equation for one sweaty commuter.

I've also used Scoot which gets me to work a little faster than Chariot, but depends on there being scooters available and is more of a commitment than Chariot given Scoot's subscription (Scoot is awesome though!). Quite a few of my coworkers gave up on any sort of shared transit, and drive to work pretty regularly.

As a comparison, it took me a little over an hour to get to work using the CalTrain when I lived in Palo Alto and had a 35mile commute.

Another example would be going from Chelsea to the Lower East Side in NYC (about the same distance as Marina to SOMA). Takes between 25-30min using the subway on Google Maps.

https://www.google.com/maps/dir/Chelsea,+New+York,+NY/Lower+...

The Marina to SOMA takes closer to 40min, but that's assuming you can get on the bus, which during rush hour is surprisingly difficult (like the article refers, you might wait 3-5 buses to find one with space).

https://www.google.com/maps/dir/Marina+District,+San+Francis...

Google tells me the average human walks 3.1 miles per hour. So I'm guessing it would take at least 55 minutes, no less.