That pretty-much sums it up. Gas tax dollars spent on anything other than roads is a waste. If the bikers want bike paths, let the bikers pay for them.
It's been in construction for close to 5 years already. It's probably got 3 or 4 years left. They are adding some badly needed lanes and overpasses - generally "modernizing" about a 18 mile strectch of freeway that was essentially unchanged from the mid-1960's. And even then, it was obsolete for the traffic it carried from the very first day.
It's done in stages. Two of the stages were barely over two miles of freeway, each. Like 2.1 and 2.3 miles, but don't quote me. The low bid for each stage was between 155 and 160 million. Simple math rounds that off to $75 million PER MILE. Of course that's for interstate specs - probably the most expensive way to construct a highway on the planet.
Nonetheless, a little more simple math shows that this 18 miles of freeway is in the neighborhood of 1.5 billion, all by itself. Now I agree with everyone that diverting this money to bike trails, and a few million to upgrade the governor's mansion all takes away from the bottom line. But let's look at the big picture. Losing a few million here and there, when we need untold billions to build, maintain, and expand our roads is a rounding error.