What you are describing is a level of planning and in this case I seriously doubt this project was planned.
The only reason I brought up this one particular example is I still remember it very clearly.
I'd walk home from work and I was constantly amazed as to how bad the traffic would flowed. Every street was full of cars and on many occasions I'd notice I was actually walking faster than the cars on the street (i.e. I'd see the same car at multiple intersections as I along the street).
But on the day the tunnel opening all that changed and the traffic turn from walking pace to gridlock.
The road closure had created a situation where now no cars where moving.
Prior to the tunnel, the driving public had faced 40+ minute traffic delays trying to get out of the city but after the opening that delay jumped to 1.5 hours.
So obviously, who ever signed off on those road changes was never acting on the best interest of the driving public.
If they had been working on some sort of plan on improving the traffic flows they failed miserably.
You’d need to figure out what’s happening with the rest of the roads, then make a call to build or not. If the plans for the other roads change, the value of your tunnel might go to zero.