This westbound is departing Roslyn for Jamaica. The LIRR 615 cab car is a former SP&S FA-1.
An FA-1 "power pack" trails train 8706. This unit was built as SP&S 864, later BN 4116 before being rebuilt to provide HEP for LIRR commuter trains.
Long Island Railroad Eastbound and Westbound trains meet at Kings Park Station on the Port Jefferson Branch.