There are two tracks leading from Manhattan to the west and south of the country. These tracks are shared between both commuter trains from the New Jersey subur

There are two tracks leading from Manhattan to the west and south of the country. These tracks are shared between both commuter trains from the New Jersey suburbs (population 4.5 million) and Amtrak. Elsewhere, there are still two tracks in places. The particular problem segment being discussed here does have four tracks, but it has commuter, regional, and intercity services. This is causing congestion problems; IIRC UK HS2 is being built because of a similar problem where they need to get the intercity trains out of the way of fast regional services.