Here in New Jersey, the quietest route is said to be State Route 49. That's 54 miles of roadway between Pennsville Township, Salem County, and Upper Township, Cape May County.
Back in 2003, Boston started the transformation of putting all their main highways underground. See the final result and should it be done in New Jersey.
There is federal funding from heading to Monmouth County government to replace the Rumson-Sea Bright Bridge and for a study on the Laurel Avenue Bridge which has become a landing spot for several 18-wheelers.