The cost is only $2 million. The cost of the bridge must be in the $20-50 million range. Or more. Actually, I have no idea other than it must be way more than $2 million.
There are a couple blocks of Regents that are just 2 lanes, from Genesee to Executive Dr, then it goes to 4 lanes until almost the end at the canyon rim.
Seems pretty low priority, but there might be a few hours a day when 4 lanes are needed.