Please understand that the initial construction of the road is one tenth the total cost of that road's lifetime cost. Maintenance makes up 90% of a road's lifetime cost. Add to the number of bridges that require even more frequent maintenance, this becomes quite a cost. That is why states are not in any rush to construct new roads, because they see that in later years, maintenance of the new roads will cost more and more of the budget.
Addtionally, the Turnpike was built in 1940 and road construction standards and speeds have changed quite a bit. I have seen advertising for the Turnpike from 1940 that envisioned picnicers using the median strip for picnics!
Transportation is too important to neglect. The state needs almost $500 million in the next few years just to maintain the existing system. Let's not penny pinch when it comes to public safety and transport.