Having driven to Chambers Bay, I don't think it's possible to be worse. It's just a tough drive with no traffic - I can't imagine a US Open.
Having a rail station will help significantly, but you know folks will try to drive. It'll be interesting to see how the US Am goes later this year.
By the way, I didn't play CB, but loved the experience of walking on its perimeter trail. The course looks wonderful (although I think it needs some grow-in TLC)