Route 15 is a state highway in the U. The unified designation was applied to these separate highways in to provide a continuous through route from New York to Massachusetts.
The parkway section of Route 15 is often referred to locally as "The Merritt". The highway comes into the state of Connecticut, continuing as the Merritt Parkway , a four-lane controlled-access parkway with low bridges, sharp curves, and a tree-filled median, that passes through the affluent urbanized areas of southern Fairfield County. Commercial vehicles are prohibited on this section of Route The parkway heads into the town of Greenwich , where it passes a service plaza in both directions and curves north-northwest, before heading northeast and meeting interchanges at Round Hill Road, providing access to Downtown Greenwich, and at Lake Avenue.
From there, Route 15 turns northeast, and curves through its interchange with North Street, which provides another outlet into Downtown Greenwich. Past this interchange, the parkway enters the city of Stamford , where it crosses over the Mianus River within the Mianus River State Park , before reaching an interchange with Route in the residential areas of North Stamford , providing access to Downtown Stamford and the University of Connecticut Stamford Campus. Route 15 continues to an interchange with Route before the route leaves Stamford.
After crossing the Fivemile River, the parkway enters the city of Norwalk and immediately comes to an interchange with Route , which provides access to the Norwalk Community College. Just past its crossing of the Silvermine River , Route 15 meets the U. Route 7 US 7 freeway at an incomplete interchange before it crosses over the Danbury Branch of the New Haven Line just south of the Merritt 7 station , and the Norwalk River and comes to a cloverleaf interchange with Main Avenue which provides the missing movements between the parkway and US 7.
From there, Route 15 continues northeast through residential areas in the neighborhood of Cranbury before it leaves Norwalk, after crossing over Route 53 without an interchange. Route 15 turns to the northeast again, upon reaching its interchange with Route 57 , that has a park and ride lot serving the town of Westport in its northwest corner. Immediately after this interchange, the parkway crosses over Route with no access and enters its longest stretch without exits, where it passes more wooded residential areas and comes into the town of Fairfield , where it meets its next interchange, five and a half miles later, at Route 58 , which also has a park and ride lot, located in its southeastern corner.
