During our recent "day wtihout Mexicans" day here in California, we had no traffic problems at all.
The fact is that with the illegals off the road it was a perfect driving day noted by virtually every news outlet.
Maybe the problem is not a lack of roads but...
On the other hand, Californias pay a huge tax on our gas that was to to to roads but never was so now they still want the tax and, add more debts via bonds to burden the california tax payer.