Interchange of the Week-#62

Orientation: Interstate 90, the New York State Thruway, runs from top left to bottom right. Interstate 890 enters at top right, ending at the Thruway interchange. NY 7 enters at top on Curry Road, then turns onto I-890, which it overlaps for two interchanges, toward top right. Curry Road continues eastward; for a short distance east of I-890 (visible as lighter-colored pavement) it is reference route 913G. NY 146 runs from bottom to top at left.

Exit numbers: Exit 25 on the New York State Thruway is for I-890, NY 7 and NY 146 to Schenectady. From I-890 eastbound (approaching the termius), Exit 9A is for NY 7 west and Exit 9B is for NY 146. Westbound, Exit 9 is for NY 7 west to NY 146. The Thruway interchange is not numbered as an exit from I-890, being its terminus.

The interchange: Thruway Interchange 25 is a perfectly typical "trumpet" design, and marks one end of an Interstate loop from I-90, like Exit 23 and several others. Also like Exit 23, there is an adjacent connection between the loop route and nearby surface highways. In this case, the predecessor to the current interchange was one with NY 146, and part of the old interchange is retained as the spur ramp to NY 146. This serves only the eastbound lanes of I-890; the westbound ramps connect to Curry Road instead. Because most traffic moves to and from the west (NY 7), the ramps are looped to eliminate left turns for these predominant movements. Channelized turns serve the eastward portion of Curry Road. An additional eastbound exit ramp provides a direct connection to NY 7 as well.

Where NY 146 crosses over the Thruway, stubs of its former alignment can be seen here. Also discernible, by vegetation features, is the Albany/Schenectady County line, which runs diagonally across the top, through the I-890/NY 7 interchange.

Orientation: The New York State Thruway (I-90) runs from top to bottom right. I-88 enters at bottom left and ends at the Thruway. The Canadian Pacific Railway runs along its north side.

Exit numbers: Exit 25A on the New York State Thruway is for I-88 to Schenectady (via NY 7) and Binghamton. This interchange is not a numbered exit from I-88, but coincidentally the next interchange westward on the route is Exit 25 (see below).

The interchange: In this example, the Thruway interchange was added with the building of a new Interstate (I-88), hence the suffixed exit number. Again, the interchange is a trumpet, and marks the eastern terminus of I-88 (the western terminus is featured in Week 45). The railroad overpass traverses the gore points of two of the interchange ramps, which are therefore extended somewhat. At bottom left is a parking area for tandem truck trailers.

Just to the west on I-88 is Exit 25 (above), for NY 7 to Rotterdam. This interchange is based on a trumpet configuration, but because of the railroad tracks along the north side of I-88, the ramps are arranged more like a diamond interchange (the result might be termed a "one-sided diamond"). Note that entering and exiting traffic cross at this point: in this case, exiting traffic yields to entering. I-88 runs parallel to NY 7 for its entire length, and has several more interchanges with it, of design similar to this one. However, in most other cases the connecting roadway has its own reference route number, whereas in this instance it is considered a ramp from I-88. (This is deduced from reference markers for route "88I" posted along the connector, although their legend is confoundingly non-standard. Still, their presence solidifies the classification of this interchange as a modified trumpet rather than as a diamond.)

Orientation: The Thruway runs from top left to bottom. Interstate 890 begins at the Thruway interchange and runs toward the right. Its continuation toward the top is NY 890, which ends at NY 5 just across the Mohawk River (the full-size image shows its entire length). NY 5S enters at top left and ends at the interchange. The CSX Railroad runs through the center of the photo. Snaking along the river side of I-890/NY 890 and NY 5S is the New York State Canalway Trail.

Exit numbers: Exit 26 on the Thruway is for I-890, NY 5 (via NY 890) and NY 5S to Schenectady and Scotia. From I-890 and NY 890, Exit 1A is for NY 5S to Rotterdam Junction and Exit 1B is for the New York State Thruway (I-90).

The interchange: Originally this was an interchange with NY 5S, which once ran farther east into Schenectady. This was probably a double trumpet interchange (having the toll plaza between two trumpet interchanges), the basis for the present configuration. When I-890 was constructed it superseded NY 5S east of here, and it was probably somewhat later that the Thruway interchange was modified into the current high-speed design with elongated exit ramps. By comparison, the "head" of the I-890 trumpet retains a much tighter curvature, which is original to the interchange.

The most recent addition was the NY 890 extension across the Mohawk River, opened in 1999. In fact, grading and structures for the extension had been completed with I-890 years before, but the road was not paved and opened to traffic until the Mohawk River Bridge was built.

What exists now is essentially the original double trumpet (connecting the Thruway with I-890/NY 890) with a third trumpet (connecting NY 5S to I-890/NY 890) overlapping it. However, in this third trumpet, the ramp from NY 5S to NY 890 is not located where it normally would be, having been relocated from the original design (there is still space enough for it under the NY 890 overpass). Instead, it branches off of the I-890 ramp, making two loops to reach NY 890 (the second loop being that of the double trumpet).

All text and images created by N. W. Perry unless otherwise credited.
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