Widening a highway is a lot more involved than people might realize, especially in a densely populated state that never built the highway correctly in the first place nor kept adequate rights of way alongside it.
-Bridges in the roadway have to be widened or replaced.
-Bridge spans over the roadway often have to be lengthened, and usually require new pilings.
-Light poles need to be moved.
-Overhead sign gantries need to be replaced with longer ones
-Storm sewers need to be replaced (can't have a storm grate that used to be in the shoulder now in the middle of a lane).
-Some ramps need to be redone if their curve would be too tight to get to the widened roadway. New Jersey already has problems with trucks overturning on ramps that turn too tightly.
Because it's a road like the New Jersey Turnpike running through developments built right up to the roadway edge, they can't build temporary lanes alongside the active lanes but instead have to do all the work on the active roadway. It's like renovating your house while living in it every day.
All that above is just for the roadway and connecting roadways. Add in nearby rail lines and crossing rail lines and it's a whole other level of pain.
Yes. I wouldn't want to have been a property owner alongside the TP when they dual-dualized the stretches from
-just south of exit 8a (Route 32 to just south of exit 9 (Route 18)
and
-just south of exit 6 (PA TP) to just south of exit 8a.
Riding tour buses to NYC through that stretch a couple of times in the early 2010s, I could see where they had to lengthen the bridges over the turnpike.
ff