There's also one on TV Highway in Hillsboro going towards Beaverton.
I believe what the billboards do is give people in the metro area a sure signal that, yes, PSU is indeed underway building a quality football program for the metro area. Its effect will not be to increase attendance per se as it does not matter how many reminders one gets if a person is not intent on attending a game of a program in incubation.
What will increase attendance is when metro area fans-in-waiting recognize that the program has crossed the decided all-or-nothing threshold signaling to them that the program is now indeed stable, growth is reasonably assured and the program is confidently on its way to legitimacy. Then people will want in. Then we will begin to see the first healthy spike of attendance over and above our 7500 (approx.) base to establish an expected new attendance base average, perhaps to mirror that of the Timber's Army.
The billboards signal the intention of the Athletic Department to build and establish a legitimate football program for the Portland metro region.
Whereas minor league baseball is appropriate for Portland now, minor league (I-AA) college football is not. It needs to be Ducks-Beavers-Vikings playing at the same I-A level. It is scandalous that our largest state university still plays I-AA sports. If our Vikings become a I-AA level team in transition, however, intent on rising to I-A, the joy of coming to a game even now would be to cheer on the rising PSU program and domination of their I-AA opposition, watch them outclass their opponents, and that would be worth the price of admission.