Widening roads does NOT relieve congestion. Longer off ramps and sympathetic traffic signals do.
I guess you have never driven on the New Jersey Turnpike or Garden State Parkway. The Turnpike is 12 lanes, 6 on each side, 3 car 3 truck/car so it is really 4 sets of 3 lanes. It used to merge down to a 6 lane highway in Cranbury, and the highway would jam up for miles, sometime 10-15 miles if it is peek summer/commuter when commuters and shore traffic double the amount of south bound traffic going to the shore. But that part of highway was expanded to continue the 12 lanes all the way down to exit 3. Now the congestion doesn’t happen on the Turnpike. Unless of course they close the Truck lanes for whatever reasons.
As for the Garden State, it is 10 lanes, 5 on each side from the Turnpike to I-78, then it sheds a lane on each side going to 280, then sheds another lane, and yes it gets congested as more lanes are shed. (going north bound) Lanes are added going southbound.
Adding lanes does help with congestion, but the roads connecting to these highways need to handle the capacity as well.
Mass transit is a dream of lefties, who want everyone else to take the loser cruiser to work while they all take their own cars. Problem is nobody wants to take the loser cruiser cause it takes forever. Trains can work, then you have rail congestion plus train stations are located in some of the worse places imaginable. Seacucus station is located in the middle of a swamp surrounded by refiners, why? It makes no sense to have a station far away from jobs and residential areas. But it exists, and it was recently built as well.
The Turnpike is a long stretch of toll road with very few on/off ramps.
Actually, the extension of the dual carriageways runs down to Exit 6, where the rerouted I-95 splits from the New Jersey turnpike to connect with the Pennsylvania Turnpike just across the Delaware River.