Interchange of the Week
Monday, 4 June 2001
New York State Thruway - Exits 14A to 15A, Spring Valley-Hillburn
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Exit 14A

Orientation: The New York State Thruway mainline, carrying Interstates 87 and 287, runs right to left. The Thruway's Garden State Parkway Connection enters at bottom and ends at the mainline. Rockland CR 35 (Pascack Road) runs from bottom to top at right.

Exit numbers: Exit 14A on the New York State Thruway is for the Garden State Parkway to New Jersey.

The interchange: Typical of situations where one controlled-access highway terminates at another, this interchange takes the "trumpet" design. There is one modification, however: motorists on the northbound Garden State Parkway Connection have the option to exit onto Rockland CR 35. This ramp, signed simply "Nanuet", branches from the northbound-to-eastbound ramp of the trumpet interchange. This is the reason for the early divergence of the eastbound exit ramp from the westbound (the split occurs in advance of the overpass at bottom).

On the ramp from the Garden State Parkway Connection to the northbound (westbound) Thruway, notice a set of yellow stripes across the roadway. These indicate a series of rumble strips, spaced a decreasing distance apart, to warn motorists of the upcoming sharp curve. The concept of tactile or auditory traffic control devices (i.e., rumble strips or shoulder/centerline grooves) is not new, but has been applied much more heavily over the past ten years or so, usually to considerable benefit.

Garden State Parkway Connection
A separate page gives an overview of this shortest segment of the Thruway system and its single interchange.

Exit 14B (left)

Exit 14B is one of the Thruway's newest interchanges, despite having been constructed in 1974 shortly after the limit of the ticket system was moved from Spring Valley to Harriman. It is a simple diamond interchange with Rockland CR 89 (Airmont Road).

Additional information from Marc Pollak

A full-size image (664 KB) is also available.

Exit 15

Orientation: The Thruway runs from right to top left, carrying Interstate 87 throughout. Interstate 287 leaves the Thruway at this point, curving from right to bottom toward Mahwah, New Jersey. NY 17 also leaves the Thruway at this point, branching from it at top and joining with I-287 for a short distance at bottom. Once inside New Jersey, the route branches off as NJ 17. NY 59 is the surface road running from top to bottom right, parallel to the Ramapo River and the Norfolk Southern Railroad. It briefly overlaps US 202 in the Village of Suffern at extreme bottom right.

The Village of Hillburn is at upper left. A section of old NY 17 enters at left.

Exit numbers: Exit 15 on the Thruway is for I-287 and NJ 17 south.

The interchange: This is a semi-directional T interchange that also features an entrance to I-287 south from old NY 17. The interchange dates back to just after the completion of I-287's New Jersey section in 1993. Before that time, Exit 15 led to NJ 17 by way of a stub end of I-287. Moreover, NY 17 formerly ran along its own separate roadway, joining I-287 just south of the Thruway. This roadway still exists, although NY 17 now overlaps I-87 and I-287, beginning from the new Exit 15A just north of the photo.

This separate page displays the previous configuration of this interchange, as well as the former routing of NY 17.

A full-size image (213 KB) is also available.

Exit 15A

Orientation: The Thruway runs from bottom to top. NY 17 enters at top left, and joins with the Thruway at the interchange, running south toward Exit 15. NY 59 begins at this point and continues on toward lower right. NY 17's former alignment turns off from NY 59 and passes under the Thruway, continuing toward the bottom left.

Exit numbers: Exit 15A on the New York State Thruway is for NY 17 north (west) and NY 59, with destinations of Sloatsburg and Suffern.

The interchange: The unusual geometry of this intersection results in an irregular form of the "folded" diamond configuration. The four ramps provide connections in all directions for NY 17, both old and new, and NY 59. In addition, there is a second southbound entrance to the Thruway for NY 17 south (east) only. In all, there are three possible entrances to points south for southbound travellers on old NY 17, including the entrance to I-287 south above.

Before the construction of Exit 15A in 1994, all movements between NY 17 and the Thruway, as well as I-287, were handled at a single point on I-287. See the history page for a map of this.

New York State Thruway,
Garden State Parkway, and
Interstate 287 (New Jersey) at Steve Anderson's
New York State Thruway Authority official site.
Garden State Parkway official site (New Jersey Turnpike Authority).

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