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Orientation: Interstate 490 runs from bottom to top right, and NY 531 branches from it to top left. NY 33 runs along Buffalo Road from left to right.
Exit numbers: Exit 7A from I-490 westbound (top to bottom as shown above) is for NY 33 east, while Exit 7B is for NY 33 west. Exit 8 is for NY 531 to Spencerport and Brockport. From I-490 eastbound, Exit 7 is for NY 33 east, and Exit 8 is for both NY 33 west and NY 531.
The interchange: These two interchanges present a good example of overlapping forms. In this case, as in a great many others, two standard designs are modified only slightly in order to avoid weaving problems inherent with closely-spaced interchange ramps.
Had the junction of I-490 and NY 531 been constructed as a true directional-T, then Exit 8 eastbound would have been a left-hand exit. Traffic entering from NY 33 westbound intending to use NY 531 would then have to cross the through lanes of I-490 within a short distance. To avoid this problem, the Exit 8 ramp was made into a right-hand exit and combined with the exit for NY 33 west. As a result, the ramp that would have carried traffic from NY 33 west to I-490 east instead only leads to NY 531. To provide the missing connection, a left turn from NY 33 west was made available to the loop ramp from NY 33 east to I-490 east. A more costly option would have been to construct a branch of the ramp from NY 33 west, crossing under the Exit 8 eastbound ramp.
The interchange between I-490 and NY 33 is the only full cloverleaf in the Rochester area, albeit a slightly modified one. A true full cloverleaf formerly existed at I-490 and NY 31F, but this has been reconfigured.
A vestige of the road's original intent still exists in the NY 204
designation, which follows the Airport Expressway, Chili Avenue, and
Avenue to the airport entrance and I-390.