There are three (3) Highway Patrol Precincts in NYPD, as well as one combined unit in Staten Island.
As well as traffic functions on the Expressways and Parkways, they also provide escorts for protective details.
They have an investigative unit for MV incidents involving deaths, and a DUI testing capability.
You will often see HWY in Manhattan on red light overtime details as well as Graffiti Patrol.
Highway is a Detail, and thus coveted by certain people.
Speaking as a cop and Patrol Supervisor (now retired), Highway rarely responded to accidents on the roads they covered unless it was a major incident.
The only NYSP that operate within NYC are those assigned to the various Task Forces.
Marked NYSP units did patrol for a period of time after the muslims attacked NY. They, along with some NG units provided back up at the various choke points.
There is No NYSP Troop assigned to NYC.
Note that NYC is not just, as the elitists are fond of saying, Manhattan. Staten Island has three Precincts, just one of which covers more area then Manhattan.
Likewise Brooklyn and Queens are large cities unto themselves, and all the boro's (possibily with the exception of The Bronx could be stand alone large cities.
There are multiple Parkways and Expressways running through and around the perimeter of NYC.
So, why do you think it funny that NYPD has a Highway Patrol Unit?