It serves as one of the main thoroughfares in the town of Old Saybrook, intersecting twice with U.S. Route 1 (US 1).

It heads south on Great Hammock Road as it is parallel to the Long Island Sound.

It becomes known as Plum Bank Road, shortly before turning eastward as Indianola Drive as it enters Knollwood.

The section of Route 154 in the town of Haddam (9.16 miles long) is also a state scenic road.

This portion of the route runs alongside the west bank of the Connecticut River.

At the same time, a loop route in Old Saybrook, serving the borough of Fenwick was designated as State Highway 338.

[2] Its original route started at US 1 in Old Saybrook Center and followed Main Street then College Street to Saybrook Point, then continued through Fenwick along Maple Avenue to end at itself just south of the town center.