They're humping that area for a few reasons. Also it's not spring, haha!
One, there's going to be tree work for the next few weeks at 84 and Portola Rd. The lower half of 84 between Skyline and Portola will be closed Mon-Fri 8AM-4PM, but the section near Skyline on 84 will still be open so that residents can still get out and back in. So, between the work and closure as you near the bottom, they don't want people flying through there and stuffing it into the work zone or closure point.
Second, I know that the people that live near Alices have had enough of people going "fast" through there, and have been complaining a lot recently. I put fast in quotes, because the people that live near that intersection, view anyone going above 25mph as going too fast. Seriously, they drive like tourists in there, it's painful(that's part of my commute). I'm sure there are those that fly through there, but I never see it. Also, that intersection at Skyline has always been easy tickets, as lots of people just roll through the stop sign, or pull out without looking first. I've seen lots of accidents at that intersection.
Personally, I wish they'd hand out failure to yield tickets to those coming out of Alices onto 84, or crossing through, as 99% of people just blast through, people already on 84 be damned. I almost plowed into a new rider once, he just darted out without so much as a glance to his left. I nearly got hit yesterday too, by a moron in a truck that stopped at the last second, missing me by mere inches.
Be careful out there, people don't pay much attention these days, and it's much worse in the hills as of late.